ADC Therapeutics (ADCT) F-3Shelf registration (foreign)

As filed with the Securities and Exchange Commission on March 15, 2023.

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM F-3

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

ADC THERAPEUTICS SA

(Exact name of Registrant as specified in its charter)

Biopôle

Route de la Corniche 3B

1066 Epalinges

Switzerland

+41 21 653 02 00

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

ADC Therapeutics America, Inc.

430 Mountain Avenue, 4th Floor

Murray Hill, NJ 07974

(908) 546-5556

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: From time to time after the effectiveness of this registration statement.

If only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.C. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.C. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933. Emerging growth company ☐

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

† The term “new or revised financial accounting standard” refers to any update issued by the Financial Accounting Standards Board to its Accounting Standards Codification after April 5, 2012.

The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until this registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

ADC Therapeutics SA (the “Company”) is filing this registration statement, which contains two prospectuses:

The base prospectus immediately follows this explanatory note. The specific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement to the base prospectus. The sales agreement prospectus supplement immediately follows the base prospectus. The common shares that may be issued and sold pursuant to the sales agreement prospectus supplement are included in the $300,000,000 of securities that may be issued and sold by the Company pursuant to the base prospectus. Any portion of the $150,000,000 included in the sales agreement prospectus supplement that remains unsold pursuant to the sales agreement will be available for sale in other offerings pursuant to the base prospectus and a corresponding prospectus supplement.

The information in this prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MARCH 15, 2023

PROSPECTUS

ADC THERAPEUTICS SA

$300,000,000

Common Shares
Debt Securities
Warrants
Subscription Rights
Purchase Contracts
Units

We may offer and sell from time to time, in one or more offerings, up to $300,000,000 of any combination of the following securities: common shares, debt securities, warrants, subscription rights, purchase contracts and units (collectively, the “securities”). We may offer and sell any combination of the securities described in this prospectus in different series, at times, in amounts, at prices and on terms to be determined at or prior to the time of each offering. This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus. The prospectus supplements will also describe the specific manner in which these securities will be offered and may also supplement, update or amend information contained in this prospectus. You should read this prospectus and any applicable prospectus supplement before you invest.

The securities covered by this prospectus may be offered through one or more underwriters, dealers and agents, or directly to purchasers. The applicable prospectus supplement will set forth the names of the underwriters, dealers or agents, if any, any applicable commissions or discounts payable to them and the specific terms of the plan of distribution. For general information about the distribution of securities offered, see “Plan of Distribution” beginning on page 38 of this prospectus.

Our common shares are listed on the New York Stock Exchange (“NYSE”) under the symbol “ADCT.”

Investing in our securities involves a high degree of risk. See the “Risk Factors” section beginning on page 6 of this prospectus and, if applicable, any risk factors described in any applicable prospectus supplement and in our Securities and Exchange Commission (“SEC”) filings that are incorporated by reference in this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Prospectus dated            , 2023.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement that we filed with the SEC using a “shelf” registration process. Under this shelf registration process, we may, from time to time, sell up to $300,000,000 of any combination of the securities described in this prospectus. This prospectus provides you with a general description of the securities that may be offered by us. Each time we sell securities, we will provide a prospectus supplement accompanied by this prospectus. The prospectus supplement will contain specific information about the nature of the persons offering securities and the terms the securities being offered at that time. The prospectus supplement may also add, update or change information contained in this prospectus.

Before buying any of the securities that we are offering, you should carefully read both this prospectus and any prospectus supplement with all of the information incorporated by reference in this prospectus, as well as the additional information described under the heading “Where You Can Find More Information” and “Information Incorporated by Reference.” These documents contain important information that you should consider when making your investment decision. We have filed or incorporated by reference exhibits to the registration statement of which this prospectus forms a part. You should read the exhibits carefully for provisions that may be important to you.

To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any prospectus supplement or in any document incorporated by reference in this prospectus, on the other hand, you should rely on the information in this prospectus, provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a prospectus supplement or a document incorporated by reference in this prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

The information contained in this prospectus, any applicable prospectus supplement or any document incorporated by reference in this prospectus is accurate only as of their respective dates, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or the documents incorporated by reference in this prospectus or the sale of any securities. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Neither we nor any underwriters, dealers or agents have authorized anyone to provide you with information that is different from that contained in this prospectus, any amendment or supplement to this prospectus, or any free writing prospectus we may authorize to be delivered or made available to you. Neither we nor any underwriters, dealers or agents take responsibility for, or provide assurance as to the reliability of, any other information that others may give you. This prospectus does not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful.

For investors outside the United States: Neither we nor any underwriters, dealers or agents have taken any action that would permit the offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the securities described herein and the distribution of this prospectus outside the United States.

Unless otherwise indicated or the context otherwise requires, all references in this prospectus to “ADC Therapeutics,” “ADCT,” the “Company,” “we,” “our,” “ours,” “us” or similar terms refer to ADC Therapeutics SA and its consolidated subsidiaries.

Trademarks

We own various trademark registrations and applications, and unregistered trademarks, including ADC Therapeutics, ADCT, ZYNLONTA and our corporate logo. All other trade names, trademarks and service

marks of other companies appearing in this prospectus are the property of their respective owners. Solely for convenience, the trademarks and trade names in this prospectus may be referred to without the ^® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto. We do not intend to use or display other companies’ trademarks and trade names to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

Presentation of Financial Information

Our consolidated financial statements are presented in U.S. dollars and have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). None of the consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). The terms “dollar,” “USD” or “$” refer to U.S. dollars and the term “Swiss franc” and “CHF” refer to the legal currency of Switzerland, unless otherwise indicated. We have made rounding adjustments to some of the figures included in this prospectus. Accordingly, any numerical discrepancies in any table between totals and sums of the amounts listed are due to rounding.

Market and Industry Data

This prospectus contains industry, market and competitive position data that are based on general and industry publications, surveys and studies conducted by third parties, some of which may not be publicly available, and our own internal estimates and research. Third-party publications, surveys and studies generally state that they have obtained information from sources believed to be reliable, but do not guarantee the accuracy and completeness of such information. These data involve a number of assumptions and limitations and contain projections and estimates of the future performance of the industries in which we operate that are subject to a high degree of uncertainty.

OUR COMPANY

Overview

We are a fully-integrated commercial-stage biotechnology company helping to improve the lives of those affected by cancer with our next-generation, targeted antibody drug conjugates (“ADCs”). Our flagship product, ZYNLONTA^® (loncastuximab tesirine or Lonca) received accelerated approval from the FDA on April 23, 2021, and launched commercially in the U.S. shortly thereafter, for the treatment of adult patients with relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, including diffuse large B-cell lymphoma (“DLBCL”) not otherwise specified, DLBCL arising from low-grade lymphoma, and also high-grade B-cell lymphoma. Our objective is to establish ZYNLONTA as the third line+ DLBCL standard of care while exploring ZYNLONTA in earlier lines of therapy and in combinations to expand our market opportunity. We have a strong validated technology platform including our highly potent pyrrolobenzodiazepine (“PBD”) technology and are advancing this proprietary PBD-based ADC technology to transform the treatment paradigm for patients with hematologic malignancies and solid tumors. Additionally, we have a growing toolbox of different components allowing us to work on next-generation ADC products. By leveraging our R&D strengths, our disciplined approach to target selection and our preclinical and clinical development strategy, we have created a diverse portfolio and research pipeline. Our clinical-stage PBD-based pipeline consists of two company-sponsored candidates, ADCT-901 (KAAG1) and ADCT-601 (mipasetamab uzoptirine) (AXL), as well as one clinical-stage candidate, ADCT-602 (CD22), which is being developed in collaboration with a partner. Our preclinical-stage PBD-based pipeline consists of one company-sponsored candidate, ADCT-212 (PSMA), as well as one preclinical-stage candidate, ADCT-701(DLK-1), which is being developed in collaboration with our partner, the National Cancer Institute. We are also committed to broadening our ADC platform by expanding new antibody constructs and payloads and advancing our differentiated next-generation assets.

Company and Corporate Information

We are a Swiss stock corporation (société anonyme) organized under the laws of Switzerland. We were incorporated as a Swiss limited liability company (société à responsabilité limitée) on June 6, 2011 and converted into a Swiss stock corporation (société anonyme) under the laws of Switzerland on October 13, 2015. We have three subsidiaries: ADC Therapeutics (UK) Limited, ADC Therapeutics America, Inc. and ADC Therapeutics (NL) BV. Our principal executive office is located at Biopôle, Route de la Corniche 3B, 1066 Epalinges, Switzerland and our telephone number is +41 21 653 02 00. Our website is www.adctherapeutics.com. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus or the registration statement of which it forms a part.

Implications of Being a Foreign Private Issuer

We are considered a “foreign private issuer.” Accordingly, we report under the Exchange Act of 1934, as amended (the “Exchange Act”), as a non-U.S. company with foreign private issuer status. This means that we are exempt from certain provisions of the Exchange Act that are applicable to U.S. domestic public companies, including:

We may take advantage of these exemptions until such time as we are no longer a foreign private issuer. We would cease to be a foreign private issuer at such time as more than 50% of our outstanding voting securities are held by U.S. residents and any of the following three circumstances applies: (i) the majority of our executive officers or directors are U.S. citizens or residents, (ii) more than 50% of our assets are located in the United States or (iii) our business is administered principally in the United States.

In this prospectus and in the documents incorporated by reference in this prospectus, we have taken advantage of certain of the reduced reporting requirements as a result of being a foreign private issuer. Accordingly, the information contained in this prospectus and in the documents incorporated by reference in this prospectus may be different than the information you receive from other public companies in which you hold securities.

RISK FACTORS

Investing in our securities involves risk. Before making a decision to invest in our securities, you should carefully consider the risks described under “Risk Factors” in the applicable prospectus supplement and in our then-most recent Annual Report on Form 20-F, and any updates to those risk factors in our reports on Form 6-K incorporated by reference in this prospectus, together with all of the other information appearing or incorporated by reference in this prospectus and any applicable prospectus supplement, in light of your particular investment objectives and financial circumstances. Although we discuss key risks in our discussion of risk factors, new risks may emerge in the future, which may prove to be significant. We cannot predict future risks or estimate the extent to which they may affect our business, results of operations, financial condition and prospects.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference in this prospectus contain statements that constitute ‎forward-looking statements within the meaning of Section 21E of the Exchange Act and Section 27A of the ‎Securities Act of 1933, as amended (the “Securities Act”). All statements other than statements of historical facts, ‎including statements regarding our future catalysts, results of operations and financial position, business and commercial ‎strategy, market opportunities, products and product candidates, research pipeline, ongoing and planned ‎preclinical studies and clinical trials, regulatory submissions and approvals, research and development costs, projected revenues, expenses and cash balance and ‎the timing of revenues and expenses, timing and likelihood of success, as well as plans and objectives of ‎management for future operations are forward-looking statements. Many of the forward-looking statements ‎contained in this prospectus can be identified by the use of forward-looking words such as “anticipate,” “believe,” “could,” “expect,” “should,” “plan,” “intend,” “estimate,” “will” and “potential,” among others.‎

Forward-looking statements are based on our management’s beliefs and assumptions and on information available ‎to our management at the time such statements are made. Such statements are subject to known and unknown risks and uncertainties, ‎and actual results may differ materially from those expressed or implied in the forward-looking statements due to ‎various factors, including, but not limited to, those identified ‎in the documents incorporated by reference in this prospectus. Factors that may cause such differences include, but are not limited to: the Company’s ability to achieve its financial guidance, including 2023 net product revenue guidance for ZYNLONTA and the decrease in total operating expenses for 2023 and 2024; the Company’s ability to continue to commercialize ZYNLONTA in the United States and future revenue from the same; Swedish Orphan Biovitrum AB (Sobi)’s ability to successfully commercialize ZYNLONTA in the European Economic Area and market acceptance, adequate reimbursement coverage, and future revenue from the same; our strategic partners’, including Mitsubishi Tanabe Pharma Corporation and Overland Pharmaceuticals, ability to obtain regulatory approval for ZYNLONTA in foreign jurisdictions, and the timing and amount of future revenue and payments to us from such partnerships; the Company’s ability to market its products in compliance with applicable laws and regulations; the timing and results of the Company’s or its partners’ research projects or clinical trials including LOTIS 2, 5, 7 and 9, ADCT 901, 701, 601, 602 and 212, the timing and outcome of regulatory submissions and actions by the U.S. Food and Drug Administration or other regulatory agencies with respect to the Company’s products or product candidates; projected revenue and expenses; our indebtedness and the restrictions imposed on the Company’s activities by such indebtedness, the ability to repay such indebtedness and the significant cash required to service such indebtedness; the Company’s ability to obtain financial and other resources for its research, development, clinical, and commercial activities; the manufacture and supply of our products and product candidates; our expectations regarding the size of the patient populations amenable to treatment with our products and, if approved, product candidates, as well as the treatment landscape of the indications that we are targeting with our products and product candidates; our ability to identify and develop additional product candidates; the ability of our competitors to discover, develop or commercialize competing products before or more successfully than we do; our competitive position and the development of and projections relating to our competitors or our industry; our estimates of our expenses, revenues, capital requirements, cash runway and need for or ability to obtain additional financing; our ability to identify and successfully

enter into strategic collaborations or licensing opportunities in the future, and our assumptions regarding any potential revenue that we may generate under current or future collaborations or licensing arrangements; our ability to obtain, maintain, protect and enforce intellectual property protection for our products and product candidates, and the scope of such protection; our ability to operate our business without infringing, misappropriating or otherwise violating the intellectual property rights of third parties; our expectations regarding the impact of the COVID-19 pandemic; our expectations regarding the impact of the current conflict between Russia and Ukraine, including resulting sanctions and changes in commodities prices, on our business and industry and the financial markets; our expectations regarding the impact of inflation and other market risks; our ability to attract and retain qualified key management and technical personnel; our expectations regarding the effectiveness of our internal controls over financial reporting; and our expectations regarding the time during which we will be a foreign private issuer.

Forward-looking statements speak only as of the ‎date on which they were made. Because forward-looking statements are inherently subject to risks and ‎uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you ‎should not rely on these forward-looking statements as predictions of future events. Moreover, we operate in an ‎evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for ‎management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to ‎publicly update or revise any forward-looking statements, whether as a result of any new information, future ‎events, changed circumstances or otherwise. You should read this prospectus, the documents incorporated by ‎reference in this prospectus and the documents that we have filed as exhibits to the registration statement of which ‎this prospectus is a part completely and with the understanding that our actual future results may be materially ‎different from what we expect.‎

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant ‎subject. These statements are based upon information available to us as of the date of such statements, and while ‎we believe such information forms a reasonable basis for such statements, such information may be limited or ‎incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, ‎or review of, all potentially available relevant information. These statements are inherently uncertain and investors ‎are cautioned not to unduly rely upon these statements.‎

USE OF PROCEEDS

Unless otherwise indicated in a prospectus supplement, the principal purpose of an offering would be to increase our capitalization and financial flexibility and the net proceeds from our sale of the securities will be used for general corporate purposes and other business opportunities.

DIVIDEND POLICY

We have never declared or paid cash dividends on our share capital. We intend to retain all available funds and any future earnings, if any, to fund the development and expansion of our business and we do not anticipate paying any cash dividends in the foreseeable future. In addition, agreements governing our indebtedness, including the loan agreement and guaranty, dated August 15, 2022, among us, ADC Therapeutics (UK) Limited, ADC Therapeutics America, Inc., the lenders party thereto and Owl Rock Opportunistic Master Fund I, L.P., as administrative agent and collateral agent, limit our ability to pay dividends. Any future determination related to dividend policy will be made at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements, contractual restrictions, business prospects and other factors our board of directors may deem relevant.

Under Swiss law, any dividend must be approved by our shareholders. In addition, our auditors must confirm that the dividend proposal of our board of directors to the shareholders conforms to Swiss statutory law and our articles of association. A Swiss corporation may pay dividends only if it has sufficient distributable profits from the previous business year (bénéfice de l’exercice) or brought forward from previous business years (report des bénéfices) or if it has distributable reserves (réserves à libre disposition), each as evidenced by its audited stand-alone statutory balance sheet prepared pursuant to Swiss law and after allocations to reserves required by Swiss law and its articles of association have been deducted. Distributable reserves are generally booked either as free reserves (réserves libres) or as reserves from capital contributions (apports de capital). Distributions out of share capital, which is the aggregate par value of a corporation’s issued shares, may be made only by way of a share capital reduction. See “Description of Share Capital and Articles of Association.”

DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION

The Company

We are a Swiss stock corporation (société anonyme) organized under the laws of Switzerland. We were incorporated ‎as a Swiss limited liability company (société à responsabilité limitée) on June 6, 2011 with our registered office and ‎domicile in Epalinges, Canton of Vaud, Switzerland. We converted to a Swiss stock corporation under the laws of ‎Switzerland on October 13, 2015. Our domicile is in Epalinges, Canton of Vaud, Switzerland. Our registered office ‎and head office is currently located at Biopôle, Route de la Corniche 3B, 1066 Epalinges, Switzerland.‎

As of January 1, 2023, certain amendments to the law governing, among other things, Swiss stock corporations, took effect. Provisions in the articles of association or regulations of companies that do not comply with the new rules continue to be effective until they are amended, but for not longer than two years after January 1, 2023. Our articles of association have not yet been amended to reflect the new provisions of Swiss corporation law.

Unless otherwise noted, the following is a summary of the material provisions of our share capital and our articles of association that are in effect on the date of this prospectus.

Share Capital

As of December 31, 2022, our share capital as registered with the commercial register of the Canton of Vaud, Switzerland ‎‎(the “Commercial Register”) amounted to 89,041,946 common shares, 80,642,527 of which were outstanding, with a par value of CHF 0.08 per share.‎

Changes in Our Share Capital During the Last Three Fiscal Years

In this section, share amounts are presented as of the date of the relevant transaction. Since January 1, 2020, our ‎share capital has changed as follows:‎

Registration Rights

On August 15, 2022, we entered into a registration rights agreement with Deerfield Partners, L.P. and Deerfield Private Design Fund IV, L.P. that provides them with certain registration rights with respect to the common shares issuable to them upon the exercise of their warrants. We have filed a registration

statement as required by the registration rights agreement. We are required to keep such registration statement effective until all such common shares have been sold, are eligible to be immediately sold to the public without registration or restriction, are no longer outstanding, are no longer held by persons entitled to registration rights or until the date that is one month following expiry of their warrants.

On August 15, 2022, we entered into a registration rights agreement with OR Opportunistic DL (C), L.P., Owl Rock Opportunistic Master Fund II, L.P., Oaktree LSL Holdings EURRC S.à r.l., Oaktree Specialty Lending Corporation, Oaktree AZ Strategic Lending Fund, L.P., Oaktree Strategic Credit Fund, Oaktree Diversified Income Fund, Inc. and Oaktree Loan Acquisition Fund, L.P. that provides them with certain registration rights with respect to the common shares issuable upon the exercise of their warrants and the common shares issued to OR Opportunistic DL (C), L.P. and Owl Rock Opportunistic Master Fund II, L.P. pursuant to a share purchase agreement. We have filed a registration statement as required by the registration rights agreement. We are required to keep such registration statement effective until all such common shares have been sold, are eligible to be immediately sold to the public without registration or restriction, are no longer outstanding, are no longer held by persons entitled to registration rights or the date that is three years from the initial effective date of the registration statement. The registration rights agreement includes certain demand registration rights and piggyback registration rights exercisable if we do not maintain current public information for Rule 144 purposes.

On February 6, 2023, we entered into a registration rights agreement with Oaktree Fund Administration LLC, OCM Strategic Credit Investments S.à r.l., OCM Strategic Credit Investments 2 S.à.r.l., OCM Strategic Credit Investments 3 S.à r.l., Oaktree Gilead Investment Fund AIF (Delaware), L.P., Oaktree Huntington-GCF Investment Fund (Direct Lending AIF), L.P., Oaktree Specialty Lending Corporation and Pathway Strategic Credit Fund III, L.P. that provides them with certain registration rights with respect to the common shares received after a default by A.T. Holdings II Sarl and in the event of a foreclosure or other exercise of remedies under their lending arrangements with A.T. Holdings II Sàrl. If requested by such parties, we are required to file a registration statement with respect to such common shares. We are required to keep such registration statement effective until all such common shares have been sold, are no longer outstanding, are no longer held by persons entitled to registration rights or the date that is three years from the initial effective date of the registration statement.

Articles of Association

Ordinary Capital Increase, Capital Range and Conditional Share Capital

Under Swiss law, we may increase our share capital (capital-actions) with a resolution of the general meeting of ‎shareholders (ordinary capital increase) that must be carried out by the board of directors within six months of ‎the respective general meeting in order to become effective. Under our articles of association and Swiss law, in the ‎case of subscription and increase against payment of contributions in cash, a resolution passed by a ‎majority of the shares represented at the general meeting of shareholders is required. In the case of subscription and ‎increase against contributions in kind or to fund acquisitions in kind, when shareholders’ statutory pre-emptive ‎subscription rights or advance subscription rights are limited or withdrawn or where transformation of freely ‎disposable equity into share capital is involved, a resolution passed by two-thirds of the shares represented at a ‎general meeting of shareholders and the majority of the par value of the shares represented is required.‎

As of January 1, 2023 companies can no longer adopt, increase or extend authorized share capital (capital-actions autorisé). Instead, companies may adopt a capital range as further explained below. As of the date of this prospectus, our articles of association still provide for authorized share capital (see “Description of Share Capital and Articles of Association—Our Authorized Share Capital”).

Furthermore, under the Swiss Code of Obligations (Code des obligations) (the “CO”), our shareholders, by a ‎resolution passed by two-thirds of the shares represented at a general meeting of shareholders and the ‎majority of the par value of the shares represented, can:‎

option and conversion rights granted to shareholders, the creditors of bonds and similar debt instruments, employees, members ‎of the board of directors of the Company or of any group company, or to any third parties; and

Pre-Emptive and Advance Subscription Rights

Pursuant to the CO, shareholders have pre-emptive subscription rights (droits de souscription préférentiels) to ‎subscribe for new issuances of shares. With respect to conditional capital, shareholders have (i) pre-emptive subscription rights for the subscription of option rights and (ii) advance subscription rights ‎‎(droit de souscription préalable) for the subscription of bonds and similar debt ‎instruments to which option or conversion rights are attached.‎

A resolution passed at a general meeting of shareholders by two-thirds of the shares represented and the ‎majority of the par value of the shares represented may authorize our board of directors to withdraw or limit pre-‎emptive subscription rights or advance subscription rights in certain circumstances.‎

If pre-emptive subscription rights are granted, but not exercised, the board of directors may allocate the unexercised ‎pre-emptive subscription rights at its discretion.‎

Our Authorized Share Capital

Under our articles of association, our board of directors is authorized at any time, including to prevent takeovers ‎and changes in control, until June 9, 2023 to increase our nominal share capital by a maximum aggregate amount ‎of CHF 2,460,268.08 through the issuance of not more than 30,753,351 shares, which would have to be fully paid-‎in, each with a par value of CHF 0.08 per share.‎

Increases in partial amounts are permitted. The board of directors has the power to determine the type of ‎contributions, the issue price and the date on which the dividend entitlement starts.‎

With respect to our authorized share capital, the board of directors is authorized by our articles of association to ‎withdraw or to limit the pre-emptive subscription rights of shareholders, and to allocate them to third parties or to us, ‎in the event that the newly issued shares are issued under the following circumstances:‎

This authorization is exclusively linked to the particular available authorized share capital set out in the respective ‎article. If the period to increase our share capital out of authorized share capital lapses without having been used by ‎the board of directors, the authorization to withdraw or to limit the pre-emptive subscription rights lapses ‎simultaneously with such capital.‎

Our Conditional Share Capital

Conditional Share Capital for Warrants and Convertible Bonds

Our nominal share capital may be increased, including to prevent takeovers and changes in control, by a maximum ‎aggregate amount of CHF 1,432,776.24 through the issuance of not more than 17,909,703 common shares, which ‎would have to be fully paid-in, each with a par value of CHF 0.08 per share, by the exercise of option and ‎conversion rights granted in connection with warrants, convertible bonds or similar instruments of the Company or ‎one of our subsidiaries. Shareholders will not have pre-emptive subscription rights in such circumstances, but will ‎have advance subscription rights to subscribe for such warrants, convertible bonds or similar instruments. The ‎holders of warrants, convertible bonds or similar instruments are entitled to the new shares upon the occurrence of ‎the applicable conversion feature.‎

When issuing convertible bonds, warrants or similar instruments, the board of directors is authorized to withdraw or ‎to limit the advance subscription right of shareholders:‎

To the extent that the advance subscription rights are withdrawn or limited, (i) the convertible bonds, warrants or ‎similar instruments are to be issued at market conditions; (ii) the term to exercise the

convertible bonds, warrants or ‎similar instruments may not exceed ten years from the date of issue of the respective instrument and (iii) the conversion, exchange or exercise price of ‎the convertible bonds, warrants or similar instruments has to be set with reference to or be subject to change based ‎upon the valuation of the Company’s equity or market conditions.‎

Conditional Share Capital for Equity Incentive Plans

Our nominal share capital may, to the exclusion of the pre-emptive subscription rights and advance subscription ‎rights of shareholders, be increased by a maximum aggregate amount of CHF 936,000 through the (direct or ‎indirect) issuance of not more than 11,700,000 common shares, which would have to be fully paid-in, each with a ‎par value of CHF 0.08 per share, by the exercise of options, other rights to receive shares or conversion rights that ‎have been granted to employees, members of the board of directors, contractors or consultants of the Company or ‎of one of our subsidiaries or other persons providing services to the Company or to a subsidiary through one or ‎more equity incentive plans created by the board of directors.‎

Uncertificated Securities

Our shares are in the form of uncertificated securities (droits-valeurs, within the meaning of Article 973c of the CO). ‎In accordance with Article 973c of the CO, we maintain a non-public register of uncertificated securities ‎‎(registre des droits-valeurs). We may at any time convert uncertificated securities into share certificates (including ‎global certificates), one kind of certificate into another, or share certificates (including global certificates) into ‎uncertificated securities. Following entry in the share register, a shareholder may at any time request from us a ‎written confirmation in respect of his or her shares. Shareholders are not entitled, however, to request the conversion ‎and/or printing and delivery of share certificates. We may print and deliver certificates for shares at any time.‎

General Meeting of Shareholders

Ordinary/Extraordinary Meetings, Powers

The general meeting of shareholders is our supreme corporate body. Under Swiss law, an annual general meeting of ‎shareholders must be held annually within six months after the end of a corporation’s financial year. In our case, ‎this generally means on or before June 30. In addition, extraordinary general meetings of shareholders may be held.‎

A general meeting of shareholders may take place at different places simultaneously if the votes of the participants are immediately transmitted to all meeting venues (multilocal shareholders’ meeting). If the articles of association so permit, a general meeting of shareholders may be held outside Switzerland. The board of directors may allow shareholders that are not present at the meeting venue of the general meeting of shareholders to participate and exercise their rights electronically (“hybrid shareholder meeting”). A general meeting of shareholders without a physical meeting venue but that takes place using electronic means (“virtual shareholder meeting”) may be held, subject to certain legal requirements and if the articles of association so allow. Our articles of association currently do not provide for general meetings of shareholders outside Switzerland or virtual shareholder meetings.

According to our articles of association, the following powers are vested exclusively in the general meeting of shareholders:

In addition, the following powers are vested exclusively in the general meeting of shareholders by operation of statutory law: (i) determination of the interim dividend and approval of the requisite interim financial statements and (ii) repayment of the statutory capital reserve (réserve légale).

An extraordinary general meeting of shareholders may be called by a resolution of the board of directors or the ‎general meeting of shareholders or, under certain circumstances, by a company’s auditors, liquidator or the ‎representatives of bondholders, if any. In addition, our articles of association require the board of directors to convene an extraordinary ‎general meeting of shareholders if shareholders representing at least 10% of our share capital request such general ‎meeting of shareholders in writing. The amended Swiss corporation law requires the board of directors to convene an extraordinary general meeting of shareholders if shareholders representing at least 5% of the share capital or of the voting rights so request in writing. Our articles of association do not yet comply with this lower threshold. A request for an extraordinary general meeting of shareholders must set forth the items to be discussed and the proposals to be ‎acted upon. Further, the board of directors must convene an extraordinary general meeting of shareholders and propose ‎financial restructuring measures if, based on our stand-alone annual statutory balance sheet, half of our share ‎capital and statutory reserves are not covered by our assets and a contemplated restructuring measure falls within the competence of the general meeting of shareholders.

Voting and Quorum Requirements

Shareholder resolutions and elections (including elections of members of the board of directors) require the ‎affirmative vote of the majority of shares represented at the general meeting of shareholders, unless ‎otherwise stipulated by law or our articles of association.‎

Under our articles of association, a resolution of the general meeting of shareholders passed by ‎two-thirds of the votes and the majority of the par value of the shares, each as ‎represented at the meeting, is required for:‎

In addition, a resolution of the general meeting of shareholders passed by two-thirds of the votes and the majority of the par value of the shares, each as represented at the meeting is, by operation of statutory law required for: (i) a consolidation of shares (reverse split); (ii) a capital increase through contribution by set-off; (iii) the introduction of a capital range (marge de fluctuation du capital); (iv) a conversion of participation certificates into shares; (v) a change of currency of the share capital; (vi) the introduction of a casting vote of the chairperson at the general meeting of shareholders; (vii) a provision in the articles of association regarding the holding of the general meeting of shareholders outside Switzerland; (viii) a delisting of the equity securities; and (ix) the introduction of an arbitration clause in the articles of association.

The same voting requirements apply to resolutions regarding transactions among corporations based on Switzerland’s Federal Act on Mergers, Demergers, Transformations and the Transfer of Assets of 2003, as amended (the “Swiss Merger Act”). See “—Articles of Association—Compulsory Acquisitions; Appraisal Rights.”

In accordance with Swiss law and generally accepted business practices, our articles of association do not provide quorum requirements generally applicable to general meetings of shareholders. To this extent, our practice varies from NYSE listing standards, which require an issuer to provide in its bylaws for a generally applicable quorum, and that such quorum may not be less than one-third of the outstanding voting shares.

Notice

General meetings of shareholders must be convened by the board of directors at least 20 days before the date of ‎the meeting. The general meeting of shareholders is convened by way of a notice appearing in our official ‎publication medium, currently the Swiss Official Gazette of Commerce. Registered shareholders may also be ‎informed by ordinary mail or e-mail. The notice of a general meeting of shareholders must state the date, the starting time, the form and location of the meeting, the items on the ‎agenda, the motions to the shareholders including a short explanation for these motions, the name and address of the independent representative and, in case of elections, the names of the nominated candidates. A ‎resolution on a matter which is not on the agenda may not be passed at a general meeting of shareholders, except ‎for motions to convene an extraordinary general meeting of shareholders or to initiate a special investigation, on ‎which the general meeting of shareholders may vote at any time. No previous notification is required for motions ‎concerning items included in the agenda or for debates that do not result in a vote.‎

All owners or representatives of our shares may, if no objection is raised, hold a general meeting of shareholders without complying with the formal requirements for convening general meetings of shareholders (a universal meeting). This universal meeting of shareholders may discuss and pass binding resolutions on all matters within the purview of the general meeting of shareholders, provided that the owners or representatives of all the shares are present at the meeting.

Agenda Requests

Pursuant to our articles of association, one or more shareholders whose combined shareholdings ‎represent the lower of (i) one tenth of our share capital and (ii) an aggregate par value of at least CHF 1,000,000 ‎may request that an item be included in the agenda for a general meeting of shareholders. The amended Swiss corporation law gives one or more shareholders whose combined shareholdings ‎represent 0.5% of our voting rights or of our share capital the right to request that an item including a proposal, or a proposal with respect to an existing agenda item, be included in the agenda of a general meeting of shareholders. Our articles of association do not yet comply with this lower threshold. ‎‎

To be timely, the ‎shareholder’s request must be received by us generally at least 45 calendar days in advance of the meeting. The ‎request must be made in writing and contain, for each of the agenda items, the following information:‎

In addition, if the shareholder intends to solicit proxies from the shareholders of a company, such shareholder shall notify the company of this intent in accordance with SEC Rule 14a-4 and/or Rule 14a-8.

Our business report, the compensation report and the auditor’s report must be made available for inspection by the shareholders at our registered office no later than 20 days prior to the general meeting of shareholders. Shareholders of record may be notified of this in writing.

Voting Rights

Each of our common shares entitles a holder to one vote. The common shares are not divisible. The right to vote and the other rights of share ownership may only be exercised by shareholders (including any nominees) or usufructuaries who are entered in the share register at a cut-off date determined by the board of directors. Those entitled to vote in the general meeting of shareholders may be represented by the independent proxy holder (annually elected by the general meeting of shareholders), by its legal representative or by another registered shareholder with written authorization to act as proxy. The chairman has the power to decide whether to recognize a power of attorney.

Our articles of association contain provisions that prevent investors from acquiring voting rights exceeding 15% of our issued share capital. Specifically, if an individual or legal entity acquires common shares and, as a result, directly or indirectly, has voting rights with respect to more than 15% of the registered share capital recorded in the Commercial Register, the registered shares exceeding the limit of 15% shall be entered in the share register as shares without voting rights (limitation à l’inscription). This restriction applies equally to parties acting in concert and to shares held or acquired via a nominee, including via Cede & Co., New York (or any successor), as the nominee of The Depository Trust Company (“DTC”), New York, acting in its capacity as clearing nominee. Specifically, if shares are being held by a nominee

for third-party beneficiaries, which control (alone or together with third parties) voting rights with respect to more than 15% of the share capital recorded in the Commercial Register, our articles of association provide that the board of directors may cancel the registration of the shares with voting rights held by such nominee in excess of the limit of 15%. Furthermore, our articles of association contain provisions that allow the board of directors to make the registration with voting rights of shares held by a nominee subject to conditions, limitations and reporting requirements or to impose or adjust such conditions, limitations and requirements once registered. However, any shareholders who held more than 15% prior to our initial public offering remain registered with voting rights for such shares. Furthermore, the board of directors may in special cases approve exceptions to these restrictions.

Dividends and Other Distributions

Our board of directors may propose to shareholders that a dividend or interim dividend or other distribution be paid but cannot itself ‎authorize the distribution. Dividend and interim dividend payments require a resolution passed by a majority of the shares ‎represented at a general meeting of shareholders. In addition, our auditors must confirm that the dividend proposal ‎of our board of directors conforms to Swiss statutory law and our articles of association.‎

Under Swiss law, we may pay dividends only if we have sufficient distributable profits from the previous business ‎year (bénéfice de l’exercice) or brought forward from the previous business years (report des bénéfices), or if we ‎have distributable capital reserves (réserve légale issue du capital), each as evidenced by audited stand-alone ‎statutory annual or interim financial statements prepared pursuant to Swiss law, and after allocations to reserves required by Swiss law and ‎by the articles of association have been deducted.

Under the CO at least 5% of our annual profit must be retained as statutory profit reserve (réserve légale). If there is a loss carried forward, such loss must be eliminated before allocation to the statutory profit reserve. The statutory profit reserve shall be accumulated until it reaches, together with the statutory capital reserve, 50% of our share capital recorded in the Commercial Register. In addition, we have to allocate, among other things, the net proceeds of share issuances to the statutory capital reserve. The CO permits us to accrue ‎additional reserves. Further, a purchase of our own shares (whether by us or a subsidiary) reduces the distributable reserves in an amount corresponding to the purchase price of such own shares. Finally, the CO under ‎certain circumstances requires the creation of revaluation reserves which are not distributable.‎

Distributions out of issued share capital (i.e., the aggregate par value of our issued shares) are not allowed and may ‎be made only by way of an ordinary capital reduction or within a capital range that (also) allows for a capital reduction (see “Description of Share Capital and Articles of Association—Articles of Association—Ordinary Capital Increase, Capital Range and Conditional Share Capital”). An ordinary capital reduction requires a resolution passed by a‎ majority of the shares represented at a general meeting of shareholders. The board of directors must publish a call to creditors in the Swiss Official Gazette of Commerce in which creditors are advised that they may request, subject to certain conditions, security for their claims within ‎30 days of the publication of the creditor call. A licensed audit expert must then confirm, based on the results of the call to creditors, that the claims of the creditors remain fully ‎covered despite the reduction in our share capital recorded in the Commercial Register. If all requirements for an ordinary capital reduction have been met, the board of directors has to amend the articles of association in a public deed. Our share capital may be ‎reduced below CHF 100,000 only if and to the extent that at the same time the statutory minimum share capital of ‎CHF 100,000 is reestablished by sufficient new fully paid-up capital. An ordinary capital reduction must be completed within six months after the resolution of the general meeting of shareholders.‎

Our board of directors determines the date on which the dividend entitlement starts. Dividends are usually due and ‎payable shortly after the shareholders have passed the resolution approving the payment, but shareholders may ‎also resolve at the annual general meeting of shareholders to pay dividends in quarterly or other installments.‎

Transfer of Shares

Shares in uncertificated form (droits-valeurs) may only be transferred by way of assignment. Shares or the beneficial interest in shares, as applicable, credited in a securities account may only be transferred when a credit of the relevant intermediated securities to the acquirer’s securities account is made in accordance with applicable rules. Our articles of association provide that in the case of securities held with an intermediary such as a registrar, transfer agent, trust corporation, bank or similar entity, any transfer, grant of a security interest or usufructuary right in such intermediated securities and the appurtenant rights associated therewith requires the cooperation of the intermediary in order for such transfer, grant of a security interest or usufructuary right to be valid against us.

Voting rights may be exercised only after a shareholder has been entered in the share register (registre des actions) with his or her name and address (in the case of legal entities, the registered office) as a shareholder with voting rights. For a discussion of the restrictions applicable to the control and exercise of voting rights, see “Description of Share Capital and Articles of Association—Articles of Association—Voting Rights.”

Inspection of Books and Records

Under the CO, a shareholder has a right to inspect the share register with respect to his or her own shares and ‎otherwise to the extent necessary to exercise his or her shareholder rights. No other person has a right to inspect the ‎share register. Shareholders holding in the aggregate at least 5% of our nominal share capital or of our voting rights have the right to inspect our books and correspondence, subject to the safeguarding of our business secrets and other legitimate interests. Our board of directors is required to decide on an inspection request within four months after receipt of such request. Denial of the request will need to be justified in writing. If an inspection request is denied by the board of directors, shareholders may request the order of an inspection by the court within thirty days. See “Comparison of Swiss Law and Delaware Law—Inspection of books and ‎records.”‎

Special Investigation

If a shareholder has exercised its information or inspection rights, ‎such shareholder may propose to the general meeting of shareholders that specific facts be examined by a special ‎examiner in a special investigation. If the general meeting of shareholders approves the proposal, we or any ‎shareholder may, within 30 calendar days after the general meeting of shareholders, request a court at our registered ‎office (currently Epalinges, Canton of Vaud, Switzerland) to appoint a special examiner. If the general meeting of ‎shareholders rejects the request, one or more shareholders representing at least 5% of our share capital or voting rights may request that the court appoint a special ‎examiner. The court will issue such an order if the petitioners can demonstrate that ‎members of the board of directors or our executive committee infringed the law or our articles of association and that such violation is suitable to cause a damage to the Company or the shareholders. The costs of the investigation would generally be ‎allocated to us and only in exceptional cases to the petitioners.‎

Compulsory Acquisitions; Appraisal Rights

Business combinations and other transactions that are governed by the Swiss Merger Act (i.e., mergers, demergers, ‎transformations and certain asset transfers) are binding on all shareholders. A statutory merger or demerger requires ‎approval of two-thirds of the shares represented at a general meeting of shareholders and the majority of ‎the par value of the shares represented.‎

If a transaction under the Swiss Merger Act receives all of the necessary consents, all shareholders are compelled to participate in such transaction.

Swiss corporations may be acquired by an acquirer through the direct acquisition of the shares of the Swiss corporation. The Swiss Merger Act provides for the possibility of a so-called “cash-out” or “squeeze-out” merger with the approval of holders of 90% of the issued shares. In these limited circumstances, minority shareholders of the corporation being acquired may be compensated in a form other than through shares of the acquiring corporation (for instance, through cash or securities of a parent corporation of the acquiring corporation or of another corporation). For business combinations effected in

the form of a statutory merger or demerger and subject to Swiss law, the Swiss Merger Act provides that if equity rights have not been adequately preserved or compensation payments in the transaction are unreasonable, a shareholder may request the competent court to determine a reasonable amount of compensation.

In addition, under Swiss law, the sale of “all or substantially all of our assets” by us may require the approval of ‎two-thirds of the number of shares represented at a general meeting of shareholders and the majority of ‎the par value of the shares represented. Whether a shareholder resolution is required depends on the particular ‎transaction, including whether the following test is satisfied:‎

A shareholder of a Swiss corporation participating in certain major corporate transactions may, under certain circumstances, be entitled to appraisal rights. As a result, such shareholder may, in addition to the consideration (be it in shares or in cash) receive an additional amount to ensure that the shareholder receives the fair value of the shares held by the shareholder. Following a statutory merger or demerger, pursuant to the Swiss Merger Act, shareholders can file an appraisal action against the surviving company. If the consideration is deemed inadequate, the court will determine an adequate compensation payment.

Board of Directors

Our articles of association provide that the board of directors shall consist of at least three and not more than 12 members.

The members of the board of directors and the chairman are elected annually by the general meeting of shareholders for a period until the completion of the subsequent annual general meeting of shareholders and are eligible for re-election. Each member of the board of directors must be elected individually.

Powers

According to our articles of association, the board of directors has the following non-delegable and inalienable powers and duties:‎

By operation of statutory law, the board of directors has the additional non-delegable and inalienable power and duty to submit an application for debt-restructuring moratorium if needed.

The board of directors may, while retaining such non-delegable and inalienable powers and duties, delegate some of ‎its powers, in particular direct management, to a single or to several of its members, committees or to third parties ‎‎(such as executive officers) who need be neither members of the board of directors nor shareholders. Pursuant to ‎Swiss law and our articles of association, details of the delegation and other procedural rules such as quorum ‎requirements have been set in the organizational rules established by the board of directors.‎

Indemnification of Executive Officers and Directors

Subject to Swiss law, our articles of association provide for indemnification of the existing and former members of the board of directors and the executive committee and their heirs, executors and administrators, against liabilities arising in connection with the performance of their duties in such capacity, and permits us to advance the expenses of defending any act, suit or proceeding to our directors and executive officers to the extent not included in insurance coverage or advanced by third parties.

In addition, under general principles of Swiss employment law, an employer may be required to indemnify an employee against losses and expenses incurred by such employee in the proper execution of his or her duties under the employment agreement with the employer. See “Comparison of Swiss Law and Delaware Law—Indemnification of directors and executive officers and limitation of liability.”

We have entered into indemnification agreements with each of the members of our board of directors and executive officers.

Conflicts of Interest, Management Transactions

The members of the board of directors and the executive committee are required to immediately and fully inform the board of directors about conflicts of interests concerning them. The board of directors is furthermore required to take measures in order to protect the interests of the company. More generally, the CO requires our directors and executive officers to safeguard the Company’s interests and imposes a duty of ‎loyalty and duty of care on our directors and executive officers. This rule is generally understood to disqualify ‎directors and executive officers from participation in decisions that directly affect them. Our directors and ‎executive officers are personally liable to us for breaches of these obligations. In addition, Swiss law contains ‎provisions under which directors and all persons engaged in the Company’s management are liable to the ‎Company, each shareholder and the Company’s creditors for damages caused by an intentional or negligent ‎violation of their duties. Furthermore, Swiss law contains a provision under which payments made to any of the ‎Company’s shareholders or directors or any person related to any such shareholder or director, other than payments ‎made at arm’s length, must be repaid to the Company if such shareholder or director acted in bad faith.‎

Our board of directors has adopted a Code of Business Conduct and Ethics and other policies that cover a broad ‎range of matters, including the handling of conflicts of interest.‎

Principles of the Compensation of the Board of Directors and the Executive Committee

Pursuant to Swiss law, the aggregate amount of compensation of the ‎board of directors and the persons whom the board of directors has, fully or partially, entrusted with the ‎management (which we refer to as our “executive committee”) of the Company has to be submitted to our shareholders for approval each year. Our executive committee currently comprises the Chief Executive Officer, the Chief Financial Officer, the Executive Vice President, the Chief Scientific Officer and the Chief Legal Officer.‎

The board of directors must issue, on an annual basis, a written compensation report that must be reviewed by our ‎auditors. The compensation report must disclose, among other things, all compensation granted by the Company, directly or indirectly, ‎to current members of the board of directors and the executive committee and, to the extent related to their former ‎role within the Company or not on customary market terms, to former members of the board of directors and ‎former executive officers.‎

The disclosure concerning compensation, loans and other forms of indebtedness must include the aggregate amount for the board of directors and the executive committee, respectively, as well as the particular amount for each member of the board of directors and for the highest paid executive officer, specifying the name and function of each of these persons.

We are prohibited from granting certain forms of compensation to members of our board of directors and executive committee, such as:

Compensation to members of the board of directors and the executive committee for activities in entities that are, directly or indirectly, controlled by the Company is prohibited if (i) the compensation would be prohibited if it were paid directly by the Company, (ii) the articles of association do not provide for it, or (iii) the compensation has not been approved by the general meeting of shareholders.

In each year, the general meeting of shareholders has to vote on the proposals of the board of directors with respect to:

The board of directors may submit for approval at the general meeting of shareholders deviating or additional proposals relating to the same or different periods.

If, at the general meeting of shareholders, the shareholders do not approve a compensation proposal of the board of directors, the board of directors must prepare a new proposal, taking into account all relevant factors, and submit the new proposal for approval by the same general meeting of shareholders, at a subsequent extraordinary general meeting of shareholders or the next annual general meeting of shareholders.

In addition to fixed compensation, members of the board of directors and the executive committee may be paid variable compensation, depending on the achievement of certain performance criteria. The performance criteria may include individual targets, targets of the Company or parts thereof and targets in relation to the market, other companies or comparable benchmarks, taking into account the position and

level of responsibility of the recipient of the variable compensation. The board of directors or, where delegated to it, the compensation committee shall determine the relative weight of the performance criteria and the respective target values.

Compensation may be paid or granted in the form of cash, shares, financial instruments, in kind, or in the form of other types of benefits. The board of directors or, where delegated to it, the compensation committee shall determine grant, vesting, exercise and forfeiture conditions.

Borrowing Powers

Neither Swiss law nor our articles of association restricts our power to borrow and raise funds. The decision to borrow funds is made by or under the direction of our board of directors, and no approval by the shareholders is required in relation to any such borrowing.

Repurchases of Shares and Purchases of Own Shares

The CO limits our ability to repurchase and hold our own shares. We and our subsidiaries may repurchase shares only to the extent that (i) we have freely distributable reserves in the amount of the purchase price; and (ii) the aggregate par value of all shares held by us does not exceed 10% of our share capital. Pursuant to Swiss law, where shares are acquired in connection with a transfer restriction set out in the articles of association, the foregoing upper limit is 20%. If we own shares that exceed the threshold of 10% of our share capital, the excess must be sold or cancelled by means of a capital reduction within two years.

Shares held by us or our subsidiaries are not entitled to vote at the general meeting of shareholders but are entitled to the economic benefits applicable to the shares generally, including dividends and pre-emptive subscription rights in the case of share capital increases.

In addition, selective share repurchases are only permitted under certain circumstances. Within these limitations, as is customary for Swiss corporations, we may, subject to applicable law, purchase and sell our own shares from time to time in order to meet imbalances of supply and demand, to provide liquidity and to even out variances in the market price of shares.

Notification and Disclosure of Substantial Share Interests

The disclosure obligations generally applicable to shareholders of Swiss corporations under the Federal Act on Financial Market Infrastructures and Market Conduct in Securities and Derivatives Trading, or the Financial Market Infrastructure Act (the “FMIA”), do not apply to us since our shares are not listed on a Swiss exchange.

Mandatory Bid Rules

The obligation of any person or group of persons that acquires more than one-third of a company’s voting rights to submit a cash offer for all the outstanding listed equity securities of the relevant company at a minimum price pursuant to the FMIA does not apply to us since our shares are not listed on a Swiss exchange.

Stock Exchange Listing

Our common shares are listed on the NYSE under the symbol “ADCT.”

The Depository Trust Company

Each person owning a beneficial interest in common shares held through DTC must rely on the procedures thereof and on institutions that have accounts therewith to exercise any rights of a holder of the shares.

Transfer Agent and Registrar of Shares

Our share register is kept by Computershare Trust Company, N.A., which acts as transfer agent and registrar. The share register reflects only record owners of our shares. Swiss law does not recognize fractional share interests.

Comparison of Swiss Law and Delaware Law

The Swiss laws applicable to Swiss corporations and their shareholders differ from laws applicable to ‎U.S. corporations and their shareholders. The following table summarizes significant differences in shareholder ‎rights pursuant to the provisions of the CO, by which our Company is governed (but see “Description of Share Capital and Articles of Association—The Company” regarding the two-year transition period that currently applies), and the Delaware General Corporation Law applicable to companies ‎incorporated in Delaware and their shareholders. Please note that this is only a general summary of certain ‎provisions applicable to companies in Delaware. Certain Delaware companies may be permitted to exclude certain ‎of the provisions summarized below in their charter documents.‎

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities, which may be secured or unsecured and may be exchangeable for and/or convertible into other securities, including our common shares. The debt securities will be issued under one or more separate indentures between us and a designated trustee. The terms of each series of debt securities being offered, including the terms, if any, on which a series of debt securities may be convertible into or exchangeable for other securities, and the material terms of the indenture will be set forth in the applicable prospectus supplement.

The applicable prospectus supplement will set forth, to the extent required, the following terms of the debt securities in respect of which the prospectus supplement is delivered:

DESCRIPTION OF WARRANTS

We may issue warrants to purchase our debt or equity securities. The warrants may be issued independently or together with any other securities and may be attached to, or separate from, such securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and a warrant agent. The terms of any warrants being offered and a description of the material provisions of the applicable warrant agreement will be set forth in the applicable prospectus supplement.

The applicable prospectus supplement will set forth, to the extent required, the following terms of the warrants in respect of which the prospectus supplement is delivered:

DESCRIPTION OF SUBSCRIPTION RIGHTS

We may issue subscription rights to purchase our securities. The subscription rights may be issued independently or together with any other securities, may be attached to, or separate from, such securities and may or may not be transferable by the shareholder receiving the subscription rights. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any unsubscribed securities after such offering. The terms of any subscription rights being offered will be set forth in the applicable prospectus supplement.

We may issue warrants to purchase our debt or equity securities. The warrants may be issued independently or together with any other securities and may be attached to, or separate from, such securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and a warrant agent. The terms of any warrants being offered and a description of the material provisions of the applicable warrant agreement will be set forth in the applicable prospectus supplement.

The applicable prospectus supplement will set forth, to the extent required, the following terms of the subscription rights in respect of which the prospectus supplement is delivered:

If fewer than all of the subscription rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than shareholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby arrangements, as described in the applicable prospectus supplement.

DESCRIPTION OF PURCHASE CONTRACTS

We may issue purchase contracts for the purchase or sale of debt or equity securities issued by us or securities of third parties, a basket of such securities, an index or indices or such securities or any combination of the above as specified in the applicable prospectus supplement, currencies or commodities.

Each purchase contract will entitle the holder thereof to purchase or sell, and obligate us to sell or purchase, on specified dates, such securities, currencies or commodities at a specified purchase price, which may be based on a formula, all as set forth in the applicable prospectus supplement. A purchase by us or any of our subsidiaries of common shares pursuant to any such purchase contract shall be subject to certain restrictions under Swiss law that generally apply to a repurchase of shares. We may, however, satisfy our obligations, if any, with respect to any purchase contract by delivering the cash value of such purchase contract or the cash value of the property otherwise deliverable or, in the case of purchase contracts on underlying currencies, by delivering the underlying currencies, as set forth in the applicable prospectus supplement. The applicable prospectus supplement will also specify the methods by which the holders may purchase or sell such securities, currencies or commodities and any acceleration, cancellation or termination provisions or other provisions relating to the settlement of a purchase contract.

The purchase contracts may require us to make periodic payments to the holders thereof or vice versa, which payments may be deferred to the extent set forth in the applicable prospectus supplement, and those payments may be unsecured or prefunded on some basis. The purchase contracts may require the holders thereof to secure their obligations in a specified manner to be described in the applicable prospectus supplement. Alternatively, purchase contracts may require holders to satisfy their obligations thereunder when the purchase contracts are issued. Our obligation to settle such pre-paid purchase contracts on the relevant settlement date may constitute indebtedness. Accordingly, pre-paid purchase contracts will be issued under an indenture.

DESCRIPTION OF UNITS

As specified in the applicable prospectus supplement, we may issue units consisting of one or more purchase contracts, warrants, debt securities, preferred shares, common shares or any combination of such securities. The applicable supplement will describe:

FORMS OF SECURITIES

Each debt security, warrant and unit will be represented either by a certificate issued in definitive form to a particular investor or by one or more global securities representing the entire issuance of securities. Certificated securities will be issued in definitive form and global securities will be issued in registered form. Definitive securities name you or your nominee as the owner of the security, and in order to transfer or exchange these securities or to receive payments other than interest or other interim payments, you or your nominee must physically deliver the securities to the trustee, registrar, paying agent or other agent, as applicable. Global securities name a depositary or its nominee as the owner of the debt securities, warrants or units represented by these global securities. The depositary maintains a computerized system that will reflect each investor’s beneficial ownership of the securities through an account maintained by the investor with its broker/dealer, bank, trust company or other representative, as we explain more fully below.

Registered Global Securities

We may issue registered debt securities, warrants and units in the form of one or more fully registered global securities that will be deposited with a depositary or its nominee identified in the applicable prospectus supplement and registered in the name of that depositary or nominee. In those cases, one or more registered global securities will be issued in a denomination or aggregate denominations equal to the portion of the aggregate principal or face amount of the securities to be represented by registered global securities. Unless and until it is exchanged in whole for securities in definitive registered form, a registered global security may not be transferred except as a whole by and among the depositary for the registered global security, the nominees of the depositary or any successors of the depositary or those nominees.

If not described below, any specific terms of the depositary arrangement with respect to any securities to be represented by a registered global security will be described in the prospectus supplement relating to those securities. We anticipate that the following provisions will apply to all depositary arrangements.

Ownership of beneficial interests in a registered global security will be limited to persons, called participants, that have accounts with the depositary or persons that may hold interests through participants. Upon the issuance of a registered global security, the depositary will credit, on its book-entry registration and transfer system, the participants’ accounts with the respective principal or face amounts of the securities beneficially owned by the participants. Any dealers, underwriters or agents participating in the distribution of the securities will designate the accounts to be credited. Ownership of beneficial interests in a registered global security will be shown on, and the transfer of ownership interests will be effected only through, records maintained by the depositary, with respect to interests of participants, and on the records of participants, with respect to interests of persons holding through participants. The laws of some states may require that some purchasers of securities take physical delivery of these securities in definitive form. These laws may impair your ability to own, transfer or pledge beneficial interests in registered global securities.

So long as the depositary, or its nominee, is the registered owner of a registered global security, that depositary or its nominee, as the case may be, will be considered the sole owner or holder of the securities represented by the registered global security for all purposes under the applicable indenture, warrant agreement or unit agreement. Except as described below, owners of beneficial interests in a registered global security will not be entitled to have the securities represented by the registered global security registered in their names, will not receive or be entitled to receive physical delivery of the securities in definitive form and will not be considered the owners or holders of the securities under the applicable indenture, warrant agreement or unit agreement. Accordingly, each person owning a beneficial interest in a registered global security must rely on the procedures of the depositary for that registered global security and, if that person is not a participant, on the procedures of the participant through which the person owns its interest, to exercise any rights of a holder under the applicable indenture, warrant agreement or unit agreement. We understand that under existing industry practices, if we request any action of holders or if an owner of a beneficial interest in a registered global security desires to give or take any action that a holder is entitled to give or take under the applicable indenture, warrant agreement

or unit agreement, the depositary for the registered global security would authorize the participants holding the relevant beneficial interests to give or take that action, and the participants would authorize beneficial owners owning through them to give or take that action or would otherwise act upon the instructions of beneficial owners holding through them.

Principal, premium, if any, and interest payments on debt securities, and any payments to holders with respect to warrants or units, represented by a registered global security registered in the name of a depositary or its nominee will be made to the depositary or its nominee, as the case may be, as the registered owner of the registered global security. None of ADC Therapeutics SA, the trustees, the warrant agents, the unit agents or any other agent of ADC Therapeutics SA, agent of the trustees or agent of the warrant agents or unit agents will have any responsibility or liability for any aspect of the records relating to payments made on account of beneficial ownership interests in the registered global security or for maintaining, supervising or reviewing any records relating to those beneficial ownership interests.

We expect that the depositary for any of the securities represented by a registered global security, upon receipt of any payment of principal, premium, interest or other distribution of underlying securities or other property to holders on that registered global security, will immediately credit participants’ accounts in amounts proportionate to their respective beneficial interests in that registered global security as shown on the records of the depositary. We also expect that payments by participants to owners of beneficial interests in a registered global security held through participants will be governed by standing customer instructions and customary practices, as is now the case with the securities held for the accounts of customers in bearer form or registered in “street name,” and will be the responsibility of those participants.

If the depositary for any of these securities represented by a registered global security is at any time unwilling or unable to continue as depositary or ceases to be a clearing agency registered under the Exchange Act, and a successor depositary registered as a clearing agency under the Exchange Act is not appointed by us within 90 days, we will issue securities in definitive form in exchange for the registered global security that had been held by the depositary. Any securities issued in definitive form in exchange for a registered global security will be registered in the name or names that the depositary gives to the relevant trustee, warrant agent, unit agent or other relevant agent of ours or theirs. It is expected that the depositary’s instructions will be based upon directions received by the depositary from participants with respect to ownership of beneficial interests in the registered global security that had been held by the depositary.

PLAN OF DISTRIBUTION

We may sell the securities in one or more of the following ways (or in any combination) from time to time:

The prospectus supplement will state the terms of the offering of the securities, including:

Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

If underwriters are used in the sale, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including:

Unless otherwise stated in a prospectus supplement, the obligations of the underwriters to purchase any securities will be conditioned on customary closing conditions and the underwriters will be obligated to purchase all of such series of securities, if any are purchased.

The securities may be sold through agents from time to time. The prospectus supplement will name any agent involved in the offer or sale of the securities and any commissions paid to them. Generally, any agent will be acting on a best efforts basis for the period of its appointment.

Sales to or through one or more underwriters or agents in at-the-market offerings will be made pursuant to the terms of a distribution agreement with the underwriters or agents. Such underwriters or agents may act on an agency basis or on a principal basis. During the term of any such agreement, shares may be

sold on a daily basis on any stock exchange, market or trading facility on which the common shares are traded, in privately negotiated transactions or otherwise as agreed with the underwriters or agents. The distribution agreement will provide that any common share sold will be sold at negotiated prices or at prices related to the then prevailing market prices for our common shares. Therefore, exact figures regarding proceeds that will be raised or commissions to be paid cannot be determined at this time and will be described in a prospectus supplement. Pursuant to the terms of the distribution agreement, we may also agree to sell, and the relevant underwriters or agents may agree to solicit offers to purchase, blocks of our common shares or other securities. The terms of each such distribution agreement will be described in a prospectus supplement.

We may authorize underwriters, dealers or agents to solicit offers by certain purchasers to purchase the securities at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. The contracts will be subject only to those conditions set forth in the prospectus supplement, and the prospectus supplement will set forth any commissions paid for solicitation of these contracts.

Underwriters and agents may be entitled under agreements entered into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments which the underwriters or agents may be required to make.

The prospectus supplement may also set forth whether or not underwriters may over-allot or effect transactions that stabilize, maintain or otherwise affect the market price of the securities at levels above those that might otherwise prevail in the open market, including, for example, by entering stabilizing bids, effecting syndicate covering transactions or imposing penalty bids.

Underwriters and agents may be customers of, engage in transactions with, or perform services for us and our affiliates in the ordinary course of business.

Each series of securities will be a new issue of securities and will have no established trading market, other than our common shares, which are listed on the NYSE. Any underwriters to whom securities are sold for public offering and sale may make a market in the securities, but such underwriters will not be obligated to do so and may discontinue any market making at any time without notice. The securities, other than our common shares, may or may not be listed on a national securities exchange.

EXPENSES OF THE OFFERING

The following table sets forth the expenses (other than underwriting discounts and commissions or agency fees and other items constituting underwriters’ or agents’ compensation, if any) expected to be incurred by us in connection with a possible offering of securities registered under this registration statement:

LEGAL MATTERS

The validity of certain securities and certain other matters with respect to Swiss law will be passed upon for us by Homburger AG, Zurich, Switzerland. The validity of certain securities and certain matters with respect to U.S. federal and New York State law will be passed upon for us by Davis Polk & Wardwell LLP, New York, New York. Any underwriters, dealers or agents will be advised by their own legal counsel concerning issues relating to any offering.

EXPERTS

The consolidated financial statements and management’s assessment of the effectiveness of internal control over ‎financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) ‎incorporated in this prospectus by reference to the Annual Report on Form 20-F for the year ended December 31, ‎‎2022 have been so incorporated in reliance on the report of PricewaterhouseCoopers SA, an independent registered ‎public accounting firm, given on the authority of said firm as experts in auditing and accounting. ‎PricewaterhouseCoopers SA is a member of EXPERTsuisse — Swiss Expert Association for Audit, Tax and ‎Fiduciary.‎

ENFORCEMENT OF JUDGMENTS

We are organized under the laws of Switzerland and our registered office and domicile is located in Epalinges, Switzerland. Moreover, a number of our directors and executive officers are not residents of the United States, and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may not be possible for investors to effect service of process within the United States upon us or upon such persons or to enforce against them judgments obtained in U.S. courts, including judgments in actions predicated upon the civil liability provisions of the federal securities laws of the United States. We have been advised by our Swiss counsel that there is doubt as to the enforceability in Switzerland of original actions, or in actions for enforcement of judgments of U.S. courts, of civil liabilities to the extent solely predicated upon the federal and state securities laws of the United States. Original actions against persons in Switzerland based solely upon the U.S. federal or state securities laws are governed, among other things, by the principles set forth in the Swiss Federal Act on Private International Law (the “PILA”). This statute provides that the application of provisions of non-Swiss law by the courts in Switzerland shall be precluded if the result would be incompatible with Swiss public policy. Also, mandatory provisions of Swiss law may be applicable regardless of any other law that would otherwise apply.

Switzerland and the United States do not have a treaty providing for reciprocal recognition of and enforcement of judgments in civil and commercial matters. The recognition and enforcement of a judgment of the courts of the United States in Switzerland is governed by the principles set forth in the PILA. This statute provides in principle that a judgment rendered by a non-Swiss court may be enforced in Switzerland only if:

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational requirements of the Exchange Act. Accordingly, we are required to file reports and other information with the SEC, including annual reports on Form 20-F and reports on Form. The SEC maintains an Internet site at www.sec.gov that contains reports, proxy and information statements and other information we have filed electronically with the SEC. As a foreign private issuer, we are exempt under the Exchange Act from, among other things, the rules prescribing the furnishing and content of proxy statements, and our executive officers, directors and principal shareholders are exempt from the reporting and short-swing profit recovery provisions contained in Section 16 of the Exchange Act. In addition, we are not required under the Exchange Act to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. companies whose securities are registered under the Exchange Act.

We have filed with the SEC a “shelf” registration statement (including amendments and exhibits to the registration statement) on Form F-3 under the Securities Act. This prospectus, which is part of the registration statement, does not contain all of the information set forth in the registration statement and the exhibits and schedules to the registration statement. We have omitted parts of the registration statement in accordance with the rules and regulations of the SEC. For more detail about us and the securities that may be offered by this prospectus, you may examine the registration statement on Form F-3 and the exhibits filed with it at the website provided in the previous paragraph.

We maintain a corporate website at www.adctherapeutics.com. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus or the registration statement of which it forms a part.

INFORMATION INCORPORATED BY REFERENCE

The rules of the SEC allow us to incorporate by reference information in this prospectus, which means that we disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference in this prospectus is considered to be a part of this prospectus. Any statement made in this prospectus or in a document incorporated or deemed to be incorporated by reference in this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or in any other subsequently filed document that is also incorporated or deemed to be incorporated by reference in this prospectus modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus. This prospectus incorporates by reference the documents listed below:

All subsequent annual reports on Form 20-F, Form 40-F or Form 10-K that we file with the SEC and all subsequent filings on Forms 10-Q and 8-K filed by us with the SEC pursuant to the Exchange Act (excluding, in each case, any information or documents deemed to be furnished and not filed with the SEC), after the date hereof and prior to the termination or expiration of the registration statement of which this prospectus forms a part, shall be incorporated by reference. We may incorporate by reference any reports on Form 6-K that we furnish to the SEC that we specifically identify in such form or in any applicable prospectus supplement as being incorporated by reference into this prospectus or such prospectus supplement (i) after the filing of the registration statement of which this prospectus forms a part and prior to the effectiveness of such registration statement and (ii) after the date of this prospectus and prior to the completion of an offering of securities under this prospectus.

You can obtain any of the filings incorporated by reference in this prospectus through us or from the SEC through the SEC’s website at www.sec.gov. Our filings with the SEC, including our Annual Reports on Form 20-F and Reports on Form 6-K and exhibits incorporated in and amendments to those reports, are also available free of charge on our website (www.adctherapeutics.com) as soon as reasonably practicable after they are filed with, or furnished to, the SEC. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus or the registration statement of which it forms a part. We will provide to each person, including any beneficial owner, to whom this prospectus is delivered, a copy of any or all the reports or documents incorporated by reference in this prospectus at no cost, upon written or oral request to us at the following address:

Investor Relations
ADC Therapeutics SA
c/o ADC Therapeutics America, Inc.
430 Mountain Avenue, 4th Floor
Murray Hill, NJ 07974
(908) 546-5556

ADC THERAPEUTICS SA

$300,000,000

Common Shares
Debt Securities
Warrants
Subscription Rights
Purchase Contracts
Units

PROSPECTUS

           , 2023

The information in this prospectus supplement is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus supplement is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MARCH 15, 2023

PROSPECTUS SUPPLEMENT

ADC THERAPEUTICS SA

Up to $150,000,000

Common Shares

We previously entered into an Open Market Sale Agreement^SM with Jefferies LLC (“Jefferies” or the “sales agent”), dated June 4, 2021, relating to the sale of our common shares, par value CHF 0.08 per share, offered by this prospectus supplement and the accompanying prospectus (such agreement, the “sales agreement”). In accordance with the terms of the sales agreement, under this prospectus supplement, we may offer and sell our common shares having an aggregate offering price of up to $150,000,000 from time to time through the sales agent.

Sales of our common shares, if any, under this prospectus supplement will be made by any method permitted that is deemed an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended (the “Securities Act”). The sales agent is not required to sell any specific amount, but will act as our sales agent using commercially reasonable efforts consistent with its normal trading and sales practices. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

The sales agent will be entitled to compensation at a commission rate of up to 3.0% of the gross sales price of any common shares sold under the sales agreement. In connection with the sale of common shares on our behalf, the sales agent will be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of the sales agent will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to the sales agent with respect to certain liabilities, including civil liabilities under the Securities Act. See “Plan of Distribution” beginning on page S-18 for additional information regarding the compensation to be paid to the sales agent.

Our common shares are listed on the New York Stock Exchange (“NYSE”) under the symbol “ADCT.” On March 10, 2023, the last reported sale price of our common shares on the NYSE was $2.74 per share.

Investing in our securities involves a high degree of risk. See the “Risk Factors” section beginning on page S-6 of this prospectus supplement and any risk factors in our Securities and Exchange Commission (“SEC”) filings that are incorporated by reference in this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Jefferies

Prospectus supplement dated            , 2023.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS SUPPLEMENT

This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of this offering. The second part is the accompanying prospectus, which is part of a registration statement that we filed with the SEC using a “shelf” registration process. The accompanying prospectus provides you with a general description of the securities that may be offered by us, some of which may not apply to this offering. This prospectus supplement and the information incorporated by reference in this prospectus supplement adds to, updates and, where applicable, modifies and supersedes information contained or incorporated by reference in the accompanying prospectus.

Before buying any of the securities that we are offering, you should carefully read both this prospectus supplement and the accompanying prospectus with all of the information incorporated by reference in this prospectus supplement, as well as the additional information described under the heading “Where You Can Find More Information” and “Information Incorporated by Reference.” These documents contain important information that you should consider when making your investment decision. We have filed or incorporated by reference exhibits to the registration statement of which this prospectus supplement forms a part. You should read the exhibits carefully for provisions that may be important to you.

To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference in this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement, provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in this prospectus supplement—the statement in the document having the later date modifies or supersedes the earlier statement.

The information contained in this prospectus supplement, the accompanying prospectus or any document incorporated by reference in this prospectus supplement is accurate only as of their respective dates, regardless of the time of delivery of this prospectus, the accompanying prospectus or the documents incorporated by reference in this prospectus or in the accompanying prospectus or the sale of any securities. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Neither we nor the sale agent have authorized anyone to provide you with information that is different from that contained in this prospectus supplement, the accompanying prospectus, or any free writing prospectus we may authorize to be delivered or made available to you. Neither we nor the sales agent take responsibility for, or provide assurance as to the reliability of, any other information that others may give you. This prospectus supplement does not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful.

For investors outside the United States: Neither we nor the sales agent have taken any action that would permit the offering or possession or distribution of this prospectus supplement in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus supplement must inform themselves about, and observe any restrictions relating to, the offering of the securities described herein and the distribution of this prospectus supplement outside the United States.

Unless otherwise indicated or the context otherwise requires, all references in this prospectus to “ADC Therapeutics,” “ADCT,” the “Company,” “we,” “our,” “ours,” “us” or similar terms refer to ADC Therapeutics SA and its consolidated subsidiaries.

Trademarks

We own various trademark registrations and applications, and unregistered trademarks, including ADC Therapeutics, ADCT, ZYNLONTA and our corporate logo. All other trade names, trademarks and service

marks of other companies appearing in this prospectus supplement are the property of their respective owners. Solely for convenience, the trademarks and trade names in this prospectus supplement may be referred to without the ^® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto. We do not intend to use or display other companies’ trademarks and trade names to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

Presentation of Financial Information

Our consolidated financial statements are presented in U.S. dollars and have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). None of the consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). The terms “dollar,” “USD” or “$” refer to U.S. dollars and the term “Swiss franc” and “CHF” refer to the legal currency of Switzerland, unless otherwise indicated. We have made rounding adjustments to some of the figures included in this prospectus supplement. Accordingly, any numerical discrepancies in any table between totals and sums of the amounts listed are due to rounding.

Market and Industry Data

This prospectus supplement contains industry, market and competitive position data that are based on general and industry publications, surveys and studies conducted by third parties, some of which may not be publicly available, and our own internal estimates and research. Third-party publications, surveys and studies generally state that they have obtained information from sources believed to be reliable, but do not guarantee the accuracy and completeness of such information. These data involve a number of assumptions and limitations and contain projections and estimates of the future performance of the industries in which we operate that are subject to a high degree of uncertainty.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights information contained elsewhere in this prospectus supplement or incorporated by reference in this prospectus supplement. This summary may not contain all the information that may be important to you, and we urge you to read this entire prospectus supplement and the accompanying prospectus and the documents incorporated by reference in this prospectus supplement carefully before deciding to invest in our securities.

Our Company

Overview

We are a fully-integrated commercial-stage biotechnology company helping to improve the lives of those affected by cancer with our next-generation, targeted antibody drug conjugates (“ADCs”). Our flagship product, ZYNLONTA^® (loncastuximab tesirine or Lonca) received accelerated approval from the FDA on April 23, 2021, and launched commercially in the U.S. shortly thereafter, for the treatment of adult patients with relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, including diffuse large B-cell lymphoma (“DLBCL”) not otherwise specified, DLBCL arising from low-grade lymphoma, and also high-grade B-cell lymphoma. Our objective is to establish ZYNLONTA as the third line+ DLBCL standard of care while exploring ZYNLONTA in earlier lines of therapy and in combinations to expand our market opportunity. We have a strong validated technology platform including our highly potent pyrrolobenzodiazepine (“PBD”) technology and are advancing this proprietary PBD-based ADC technology to transform the treatment paradigm for patients with hematologic malignancies and solid tumors. Additionally, we have a growing toolbox of different components allowing us to work on next-generation ADC products. By leveraging our R&D strengths, our disciplined approach to target selection and our preclinical and clinical development strategy, we have created a diverse portfolio and research pipeline. Our clinical-stage PBD-based pipeline consists of two company-sponsored candidates, ADCT-901 (KAAG1) and ADCT-601 (mipasetamab uzoptirine) (AXL), as well as one clinical-stage candidate, ADCT-602 (CD22), which is being developed in collaboration with a partner. Our preclinical-stage PBD-based pipeline consists of one company-sponsored candidate, ADCT-212 (PSMA), as well as one preclinical-stage candidate, ADCT-701(DLK-1), which is being developed in collaboration with our partner, the National Cancer Institute. We are also committed to broadening our ADC platform by expanding new antibody constructs and payloads and advancing our differentiated next-generation assets.

Company and Corporate Information

We are a Swiss stock corporation (société anonyme) organized under the laws of Switzerland. We were incorporated as a Swiss limited liability company (société à responsabilité limitée) on June 6, 2011 and converted into a Swiss stock corporation (société anonyme) under the laws of Switzerland on October 13, 2015. We have three subsidiaries: ADC Therapeutics (UK) Limited, ADC Therapeutics America, Inc. and ADC Therapeutics (NL) BV. Our principal executive office is located at Biopôle, Route de la Corniche 3B, 1066 Epalinges, Switzerland and our telephone number is +41 21 653 02 00. Our website is www.adctherapeutics.com. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus supplement or the registration statement of which it forms a part.

Implications of Being a Foreign Private Issuer

We are considered a “foreign private issuer.” Accordingly, we report under the Exchange Act of 1934, as amended (the “Exchange Act”), as a non-U.S. company with foreign private issuer status. This means that we are exempt from certain provisions of the Exchange Act that are applicable to U.S. domestic public companies, including:

We may take advantage of these exemptions until such time as we are no longer a foreign private issuer. We would cease to be a foreign private issuer at such time as more than 50% of our outstanding voting securities are held by U.S. residents and any of the following three circumstances applies: (i) the majority of our executive officers or directors are U.S. citizens or residents, (ii) more than 50% of our assets are located in the United States or (iii) our business is administered principally in the United States.

In this prospectus supplement and in the documents incorporated by reference in this prospectus supplement, we have taken advantage of certain of the reduced reporting requirements as a result of being a foreign private issuer. Accordingly, the information contained in this prospectus supplement and in the documents incorporated by reference in this prospectus supplement may be different than the information you receive from other public companies in which you hold equity securities.

THE OFFERING

The number of common shares outstanding before and after this offering is based on 80,642,527 common shares outstanding as of December 31, 2022, and excludes:

RISK FACTORS

Investing in our securities involves risk. Before making a decision to invest in our securities, you should carefully consider the following risks and in our then-most recent Annual Report on Form 20-F, and any updates to those risk factors in our reports on Form 6-K incorporated by reference in this prospectus supplement, together with all of the other information appearing or incorporated by reference in this prospectus supplement and the accompanying prospectus, in light of your particular investment objectives and financial circumstances. Although we discuss key risks in our discussion of risk factors, new risks may emerge in the future, which may prove to be significant. We cannot predict future risks or estimate the extent to which they may affect our business, results of operations, financial condition and prospects.

Risks Related to this Offering

You may experience immediate and substantial dilution in the book value of your investment.

If you purchase our common shares in this offering, you will experience immediate dilution in an amount equal to the difference between the purchase price per share and our then-net tangible book value per common share. See “Dilution.”

The issuance of common shares in connection with the exercise of securities convertible into or exercisable for our common shares would dilute your ownership interest and could materially affect the market price of our common shares and our earnings per share.

As of the date of this prospectus, we had outstanding warrants to purchase an aggregate of 4,940,135 common shares. To the extent that holders of such warrants elect to exercise the warrants, substantial amounts of our common shares may be issued in the future. We cannot quantify the number of common shares that will be issued in connection with the exercise, if any. However, the issuance of common shares pursuant to such exercise would dilute your ownership interest and could materially affect the market price of our common shares and our earnings per share.

The actual number of common shares we will sell under the sales agreement and the resulting gross proceeds is uncertain.

Subject to certain limitations in the sales agreement and compliance with applicable law, we have the discretion to deliver a placement notice to the sales agent at any time throughout the term of the sales agreement. The number of common shares that are sold by the sales agent after we deliver a placement notice will fluctuate based on the market price of our common shares during the sales period and limits we set in the placement notice. Because the price per share sold will fluctuate based on the market price of our common shares during the sales period, it is not possible to predict the number of common shares that will be ultimately sold or the resulting gross proceeds.

The common shares offered in this offering will be sold in “at the market offerings.” Investors who purchase our common shares in this offering at different times will likely pay different prices.

Investors who purchase our common shares in this offering at different times will likely pay different prices, and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices and numbers of common shares sold, and subject to certain limitations in the sales agreement, there is no minimum or maximum sales price. Investors may experience a decline in the value of their common shares and dilution as a result of sales made at prices lower than the prices they paid.

We have broad discretion in the use of the net proceeds from this offering, and we may not use them effectively.

We currently intend to use the net proceeds from this offering as described in “Use of Proceeds.” However, our board of directors and our management retains broad discretion in the application of the net

proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common shares. Our failure to apply these funds effectively could result in financial losses, which could have a material adverse effect on our business, results of operations, financial condition and prospects.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement and the documents incorporated by reference in this prospectus supplement contain statements that constitute ‎forward-looking statements within the meaning of Section 21E of the Exchange Act and Section 27A of the ‎Securities Act of 1933, as amended (the “Securities Act”). All statements other than statements of historical facts, ‎including statements regarding our future catalysts, results of operations and financial position, business and commercial ‎strategy, market opportunities, products and product candidates, research pipeline, ongoing and planned ‎preclinical studies and clinical trials, regulatory submissions and approvals, research and development costs, projected revenues, expenses and cash balance and ‎the timing of revenues and expenses, timing and likelihood of success, as well as plans and objectives of ‎management for future operations are forward-looking statements. Many of the forward-looking statements ‎contained in this prospectus supplement can be identified by the use of forward-looking words such as “anticipate,” “believe,” “could,” “expect,” “should,” “plan,” “intend,” “estimate,” “will” and “potential,” among others.‎

Forward-looking statements are based on our management’s beliefs and assumptions and on information available ‎to our management at the time such statements are made. Such statements are subject to known and unknown risks and uncertainties, ‎and actual results may differ materially from those expressed or implied in the forward-looking statements due to ‎various factors, including, but not limited to, those identified ‎in the documents incorporated by reference in this prospectus supplement. Factors that may cause such differences include, but are not limited to: the Company’s ability to achieve its financial guidance, including 2023 net product revenue guidance for ZYNLONTA and the decrease in total operating expenses for 2023 and 2024; the Company’s ability to continue to commercialize ZYNLONTA in the United States and future revenue from the same; Swedish Orphan Biovitrum AB (Sobi)’s ability to successfully commercialize ZYNLONTA in the European Economic Area and market acceptance, adequate reimbursement coverage, and future revenue from the same; our strategic partners’, including Mitsubishi Tanabe Pharma Corporation and Overland Pharmaceuticals, ability to obtain regulatory approval for ZYNLONTA in foreign jurisdictions, and the timing and amount of future revenue and payments to us from such partnerships; the Company’s ability to market its products in compliance with applicable laws and regulations; the timing and results of the Company’s or its partners’ research projects or clinical trials including LOTIS 2, 5, 7 and 9, ADCT 901, 701, 601, 602 and 212, the timing and outcome of regulatory submissions and actions by the U.S. Food and Drug Administration or other regulatory agencies with respect to the Company’s products or product candidates; projected revenue and expenses; our indebtedness and the restrictions imposed on the Company’s activities by such indebtedness, the ability to repay such indebtedness and the significant cash required to service such indebtedness; the Company’s ability to obtain financial and other resources for its research, development, clinical, and commercial activities; the manufacture and supply of our products and product candidates; our expectations regarding the size of the patient populations amenable to treatment with our products and, if approved, product candidates, as well as the treatment landscape of the indications that we are targeting with our products and product candidates; our ability to identify and develop additional product candidates; the ability of our competitors to discover, develop or commercialize competing products before or more successfully than we do; our competitive position and the development of and projections relating to our competitors or our industry; our estimates of our expenses, revenues, capital requirements, cash runway and need for or ability to obtain additional financing; our ability to identify and successfully enter into strategic collaborations or licensing opportunities in the future, and our assumptions regarding any potential revenue that we may generate under current or future collaborations or licensing arrangements; our ability to obtain, maintain, protect and enforce intellectual property protection for our products and product candidates, and the scope of such protection; our ability to operate our business without infringing, misappropriating or otherwise violating the intellectual property rights of third parties;

our expectations regarding the impact of the COVID-19 pandemic; our expectations regarding the impact of the current conflict between Russia and Ukraine, including resulting sanctions and changes in commodities prices, on our business and industry and the financial markets; our expectations regarding the impact of inflation and other market risks; our ability to attract and retain qualified key management and technical personnel; our expectations regarding the effectiveness of our internal controls over financial reporting; and our expectations regarding the time during which we will be a foreign private issuer.

Forward-looking statements speak only as of the ‎date on which they were made. Because forward-looking statements are inherently subject to risks and ‎uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you ‎should not rely on these forward-looking statements as predictions of future events. Moreover, we operate in an ‎evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for ‎management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to ‎publicly update or revise any forward-looking statements, whether as a result of any new information, future ‎events, changed circumstances or otherwise. You should read this prospectus supplement, the documents incorporated by ‎reference in this prospectus supplement and the documents that we have filed as exhibits to the registration statement of which ‎the accompanying prospectus is a part completely and with the understanding that our actual future results may be materially ‎different from what we expect.‎

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant ‎subject. These statements are based upon information available to us as of the date of such statements, and while ‎we believe such information forms a reasonable basis for such statements, such information may be limited or ‎incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, ‎or review of, all potentially available relevant information. These statements are inherently uncertain and investors ‎are cautioned not to unduly rely upon these statements.‎

USE OF PROCEEDS

We may offer and sell our common shares having an aggregate offering price of up to $150,000,000 from time to time through the sales agent. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time.

We intend to use the net proceeds from this offering, if any, together with our cash and cash equivalents, primarily to fund research and development and commercialization activities and for working capital and other general corporate purposes. We may also use a portion of the net proceeds to in-license or acquire or invest in complementary technologies, products, businesses or assets; however, we have no current plans, commitments or obligations to do so. Our expected use of the net proceeds from this offering represents our current intentions based on our present plans and business condition, which could change as our plans and business conditions evolve. The amounts and timing of our actual use of the net proceeds from this offering will vary depending on numerous factors. As a result, we cannot predict with certainty all of the particular uses for any net proceeds to be received or the amounts that we will actually spend on the uses set forth above. Our board of directors and our management retains broad discretion in the application of the net proceeds from this offering.

Pending the use of the proceeds from this offering, we intend to invest the net proceeds in a variety of capital preservation instruments, which may include all or a combination of short-term and long-term interest-bearing instruments, investment-grade securities, and direct or guaranteed obligations of the U.S. government. We cannot predict whether the proceeds invested will yield a favorable return.

DIVIDEND POLICY

We have never declared or paid cash dividends on our share capital. We intend to retain all available funds and any future earnings, if any, to fund the development and expansion of our business and we do not anticipate paying any cash dividends in the foreseeable future. In addition, agreements governing our indebtedness, including the loan agreement and guaranty, dated August 15, 2022, among us, ADC Therapeutics (UK) Limited, ADC Therapeutics America, Inc., the lenders party thereto and Owl Rock Opportunistic Master Fund I, L.P., as administrative agent and collateral agent, limit our ability to pay dividends. Any future determination related to dividend policy will be made at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements, contractual restrictions, business prospects and other factors our board of directors may deem relevant.

Under Swiss law, any dividend must be approved by our shareholders. In addition, our auditors must confirm that the dividend proposal of our board of directors to the shareholders conforms to Swiss statutory law and our articles of association. A Swiss corporation may pay dividends only if it has sufficient distributable profits from the previous business year (bénéfice de l’exercice) or brought forward from previous business years (report des bénéfices) or if it has distributable reserves (réserves à libre disposition), each as evidenced by its audited stand-alone statutory balance sheet prepared pursuant to Swiss law and after allocations to reserves required by Swiss law and its articles of association have been deducted. Distributable reserves are generally booked either as free reserves (réserves libres) or as reserves from capital contributions (apports de capital). Distributions out of share capital, which is the aggregate par value of a corporation’s issued shares, may be made only by way of a share capital reduction.

DILUTION

If you purchase our common shares in this offering, you will experience immediate dilution in an amount equal to the difference between the purchase price per share and our then-net tangible book value per common share.

Net tangible book value per share is determined by dividing our tangible net worth (defined as total assets, less intangible assets, less total liabilities) by the number of our common shares outstanding. Our historical net tangible book value as of December 31, 2022 was $74.4 million, or $0.92 per share. After giving effect to the assumed sale by us of $150,000,000 of common shares at an assumed public offering price of $2.74 per share, which was the last reported sale price of our common shares on the NYSE on March 10, 2023, and after deducting estimated commissions and estimated offering expenses payable by us, our as adjusted net tangible book value as of December 31, 2022 would have been $218.1 million, or $1.61 per common share, representing an immediate increase in the as adjusted net tangible book value of $0.69 per common share attributable to the purchasers in this offering and immediate dilution of $1.13 per share to purchasers in this offering.

The calculations above are based on 80,642,527 common shares outstanding as of December 31, 2022, and excludes:

TAXATION

The following discussion is based on the tax laws, regulations and regulatory practices of Switzerland and the United States as in effect on the date hereof, which are subject to change (or subject to changes in interpretation), possibly with retroactive effect.

Current and prospective shareholders are advised to consult their own tax advisers in light of their particular circumstances as to the Swiss or U.S. tax laws, regulations and regulatory practices that could be relevant for them in connection with owning and selling or otherwise disposing of our common shares and receiving dividends and similar cash or in-kind distributions on our common shares (including dividends on liquidation proceeds and share dividends) or distributions on our common shares based upon a capital reduction or reserves paid out of capital contributions and the consequences thereof under the tax laws, regulations and regulatory practices of Switzerland or the United States.

Swiss Tax Considerations

Withholding Tax

Under present Swiss tax law, dividends due and similar cash or in-kind distributions made by the Company to a shareholder of common shares (including liquidation proceeds and bonus shares) are subject to Swiss federal withholding tax (“Withholding Tax”), currently at a rate of 35% (applicable to the gross amount of taxable distribution). However, the repayment of the par value of the common shares and any repayment of qualifying additional paid-in capital (capital contribution reserves), within the limitations accepted by the legislation in force when such Dividend becomes due and the respective administrative practice, are not subject to the Withholding Tax. The Company is obliged to deduct any applicable Withholding Tax from the gross amount of any taxable distribution and to pay the tax to the Swiss Federal Tax Administration within 30 days of the due date of such distribution.

Swiss resident individuals who hold their common shares as private assets (“Resident Private Shareholders”) are in principle eligible for a full refund or credit against income tax of the Withholding Tax if they duly report the underlying income in their income tax return. In addition, (i) corporate and individual shareholders who are resident in Switzerland for tax purposes, (ii) corporate and individual shareholders who are not resident in Switzerland, and who, in each case, hold their common shares as part of a trade or business carried on in Switzerland through a permanent establishment with fixed place of business situated in Switzerland for tax purposes and (iii) Swiss resident private individuals who, for income tax purposes, are classified as “professional securities dealers” for reasons of, inter alia, frequent dealing, or leveraged investments, in shares and other securities (collectively, “Domestic Commercial Shareholders”) are in principle eligible for a full refund or credit against income tax of the Withholding Tax if they duly report the underlying income in their statements of operations or income tax return, as the case may be.

Shareholders who are not resident in Switzerland for tax purposes, and who, in each case and during the respective taxation year, do not hold their common shares as part of a trade or business carried on through a permanent establishment with fixed place of business situated in Switzerland for tax purposes, and who are not subject to corporate or individual income taxation in Switzerland for any other reason (collectively, “Non-Resident Shareholders”) may be entitled to a total or partial refund of the Withholding Tax if the country in which such recipient resides for tax purposes maintains a bilateral treaty for the avoidance of double taxation with Switzerland and further conditions of such treaty are met. Non-Resident Shareholders should be aware that the procedures for claiming treaty benefits (and the time required for obtaining a refund) may differ from country to country. Non-Resident Shareholders should consult their own legal, financial or tax advisors regarding receipt, ownership, purchases, sale or other dispositions of common shares and the procedures for claiming a refund of the Withholding Tax.

Swiss Federal Issuance Stamp Duty

The Company will be subject to the Swiss federal issuance stamp duty (droit de timbre d’émission) on the issuance of common shares of 1% of the offering price, net of certain deductions.

Swiss Federal Securities Transfer Tax

The delivery of common shares against payment of the offering price is not subject to Swiss securities transfer tax (droit de timbre de négociation). Any subsequent transactions in common shares in the secondary markets are subject to Swiss securities transfer tax at an aggregate rate of 0.15% of the consideration paid for such common shares, however, only if a bank or other securities dealer in Switzerland, as defined in the Swiss Federal Stamp Tax Act (loi fédérale sur les droits de timbre), is a party or an intermediary to the transaction and no exemption applies.

Swiss Federal, Cantonal and Communal Individual Income Tax and Corporate Income Tax

Non-Resident Shareholders

Non-Resident Shareholders are not subject to any Swiss federal, cantonal or communal income tax on dividend payments and similar distributions because of the mere holding of common shares. The same applies for capital gains on the sale of common shares subject to certain exceptions. For Withholding Tax consequences, see “—Swiss Tax Considerations—Withholding Tax.”

Resident Private Shareholders and Domestic Commercial Shareholders

Resident Private Shareholders who receive dividends and similar cash or in-kind distributions (including liquidation proceeds as well as bonus shares or taxable repurchases of common shares as described above), which are not repayments of the par value of common shares or, within the limitations accepted by the legislation in force and the respective administrative practice, qualifying additional paid-in capital (capital contribution reserves), are required to report such receipts in their individual income tax returns and are subject to Swiss federal, cantonal and communal income tax on any net taxable income for the relevant tax period. A gain or a loss by Resident Private Shareholders realized upon the sale or other disposition of common shares to a third party will generally be a tax-free private capital gain or not a tax-deductible capital loss, as the case may be. Under exceptional circumstances the capital gain may be re-characterized into a taxable dividend, in particular upon taxable repurchase of common shares as described above. When a capital gain is re-characterized as a dividend, the relevant income for tax purposes corresponds to the difference between the repurchase price and the sum of the par value of common shares and, within the limitations accepted by the legislation in force and the respective administrative practice, qualifying additional paid-in capital (capital contribution reserves).

Domestic Commercial Shareholders who receive dividends and similar cash or in-kind distributions (including liquidation proceeds as well as bonus shares) are required to recognize such payments in their statements of operations for the relevant tax period and are subject to Swiss federal, cantonal and communal individual or corporate income tax, as the case may be, on any net taxable earnings accumulated (including the dividends) for such period. Domestic Commercial Shareholders who are corporate taxpayers may qualify for participation relief on dividend distributions (réduction pour participations), if common shares held have an aggregate market value of at least CHF 1 million or represent 10% or more of our share capital. For cantonal and communal income tax purposes, the regulations on participation relief are broadly similar, depending on the canton of residency.

Domestic Commercial Shareholders are required to recognize a gain or loss realized upon the disposal of common shares in their statement of operations for the respective taxation period and are subject to Swiss federal, cantonal and communal individual or corporate income tax, as the case may be, on any net taxable earnings (including the gain or loss realized on the sale or other disposition of common shares) for such taxation period.

Swiss Wealth Tax and Capital Tax

Non-Resident Shareholders

Non-Resident Shareholders holding common shares are not subject to cantonal and communal wealth or annual capital tax because of the mere holding of common shares.

Resident Private Shareholders

Resident Private Shareholders are required to report their common shares as part of their private assets and are subject to cantonal and communal wealth tax.

Domestic Commercial Shareholders

Domestic Commercial Shareholders are required to report their common shares as part of their business assets or taxable capital, as defined, and are subject to cantonal and communal wealth or annual capital tax.

Automatic Exchange of Information in Tax Matters

On November 19, 2014, Switzerland signed the Multilateral Competent Authority Agreement. The Multilateral Competent Authority Agreement is based on Article 6 of the OECD/Council of Europe administrative assistance convention and is intended to ensure the uniform implementation of Automatic Exchange of Information (the “AEOI”). The Federal Act on the International Automatic Exchange of Information in Tax Matters (the “AEOI Act”) entered into force on January 1, 2017. The AEOI Act is the legal basis for the implementation of the AEOI standard in Switzerland.

The AEOI is being introduced in Switzerland through bilateral agreements or multilateral agreements. The agreements have been, and will be, concluded on the basis of guaranteed reciprocity, compliance with the principle of speciality (i.e., the information exchanged may only be used to assess and levy taxes (and for criminal tax proceedings)) and adequate data protection.

Based on such multilateral or bilateral agreements and the implementation of Swiss law, Switzerland collects and exchanges data in respect of financial assets, including common shares, held in, and income derived thereon and credited to, accounts or deposits with a paying agent in Switzerland for the benefit of individuals resident in a European Union member state or in a treaty state.

Swiss Facilitation of the Implementation of the U.S. Foreign Account Tax Compliance Act

Switzerland has concluded an intergovernmental agreement with the United States to facilitate the implementation of U.S. Foreign Account Tax Compliance Act. The agreement ensures that the accounts held by U.S. persons with Swiss financial institutions are disclosed to the U.S. tax authorities either with the consent of the account holder or by means of group requests within the scope of administrative assistance. Information will not be transferred automatically in the absence of consent, and instead will be exchanged only within the scope of administrative assistance on the basis of the double taxation agreement between the United States and Switzerland. On October 8, 2014, the Swiss Federal Council approved a mandate for negotiations with the United States on changing the current direct-notification-based regime to a regime where the relevant information is sent to the Swiss Federal Tax Administration, which in turn provides the information to the U.S. tax authorities.

Material U.S. Federal Income Tax Consequences for U.S. Holders

In the opinion of Davis Polk & Wardwell LLP, the following is a description of the material U.S. federal income tax consequences to the U.S. Holders, as defined below, of owning and disposing of our common shares. It does not describe all tax considerations that may be relevant to a particular person’s decision to acquire common shares.

This discussion applies only to a U.S. Holder that holds common shares as capital assets for U.S. federal income tax purposes (generally, property held for investment). In addition, it does not describe any tax consequences other than U.S. federal income tax consequences, including state and local tax consequences and estate tax consequences, and does not describe all of the U.S. federal income tax consequences that may be relevant in light of the U.S. Holder’s particular circumstances, including alternative minimum tax consequences, the potential application of the provisions of the Internal Revenue

Code of 1986, as amended (the “Code”) known as the Medicare contribution tax and tax consequences applicable to U.S. Holders subject to special rules, such as:

If an entity or arrangement that is classified as a partnership for U.S. federal income tax purposes holds common shares, the U.S. federal income tax treatment of a partner will generally depend on the status of the partner and the activities of the partnership. Partnerships holding common shares and partners in such partnerships should consult their tax advisers as to the particular U.S. federal income tax consequences of owning and disposing of the common shares.

This discussion is based on the Code, administrative pronouncements, judicial decisions, final, temporary and proposed Treasury regulations, and the income tax treaty between Switzerland and the United States (the “Treaty”), all as of the date hereof, any of which is subject to change or differing interpretations, possibly with retroactive effect.

A “U.S. Holder” is a beneficial owner of our common shares who, for U.S. federal income tax purposes, is eligible for the benefits of the Treaty and who is:

U.S. Holders should consult their tax advisers concerning the U.S. federal, state, local and non-U.S. tax consequences of owning and disposing of common shares in their particular circumstances.

Recently released Treasury regulations may in some circumstances prohibit a U.S. person from claiming a foreign tax credit with respect to certain non-U.S. taxes that are not creditable under applicable income tax treaties (the “Foreign Tax Credit Regulations”). Accordingly, U.S. investors that are not eligible for Treaty benefits should consult their tax advisers regarding the creditability or deductibility of any Swiss taxes imposed on dividends on, or dispositions of, common shares.

The discussion under “Taxation of Distributions” and “Sale or Other Disposition of Common Shares” below describes certain consequences to U.S. Holders in the event that we are not a passive foreign investment company for U.S. federal income tax purposes (a “PFIC”) during any tax year in which a U.S. Holder holds our common shares. This discussion assumes that we were not a PFIC for our 2022 taxable year, and will not become a PFIC in the foreseeable future. See “Passive Foreign Investment Company Rules” below.

Taxation of Distributions

Distributions paid on common shares, other than certain pro rata distributions of common shares, will generally be treated as dividends to the extent paid out of our current or accumulated earnings and profits (as determined under U.S. federal income tax principles). Because we do not maintain calculations of our earnings and profits under U.S. federal income tax principles, we expect that distributions generally will be reported to U.S. Holders as dividends. Dividends paid to certain non-corporate U.S. Holders may be eligible for taxation as “qualified dividend income” and therefore, subject to applicable limitations, may be taxable at rates not in excess of the long-term capital gain rate applicable to such U.S. Holder. Dividends will constitute qualified dividend income (a) for so long as the common shares with respect to which such dividends are paid are listed on the NYSE or we are eligible for benefits under the treaty and (b) we are not a PFIC in the year in which the dividend is paid or the prior taxable year. However, there can be no assurance that our common shares will be considered readily tradable on an established securities market in the future, nor (as discussed under "Passive Foreign Investment Company Rules" below) that we will not be a PFIC for any future taxable year. U.S. Holders should consult their tax advisers regarding the availability of the reduced tax rate on dividends in their particular circumstances.

The amount of a dividend will include any amounts withheld by us in respect of Swiss income taxes. The amount of the dividend will be treated as foreign-source dividend income to U.S. Holders and will not be eligible for the dividends-received deduction generally available to U.S. corporations under the Code. Dividends will be included in a U.S. Holder’s income on the date of the U.S. Holder’s receipt of the dividend. The amount of any dividend income paid in Swiss francs will be the U.S. dollar amount calculated by reference to the exchange rate in effect on the date of actual or constructive receipt, regardless of whether the payment is in fact converted into U.S. dollars at that time. If the dividend is converted into U.S. dollars on the date of receipt, a U.S. Holder should not be required to recognize foreign currency gain or loss in respect of the dividend income. A U.S. Holder may have foreign currency gain or loss if the dividend is converted into U.S. dollars after the date of receipt.

Subject to applicable limitations, some of which vary depending upon the U.S. Holder’s particular circumstances, Swiss income taxes withheld from dividends on common shares (at a rate not exceeding the rate provided by the Treaty, in the case of a U.S. Holder eligible for a reduced rate under the Treaty) will be creditable against the U.S. Holder’s U.S. federal income tax liability. The rules governing foreign tax credits are complex. For example, under the Foreign Tax Credit Regulations, in the absence of an election to apply the benefits of the Treaty, in order for foreign income taxes to be creditable, the rules imposing the taxes must be consistent with certain U.S. federal income tax principles, and we have not determined whether the Swiss income tax system meets all these requirements. U.S. Holders should consult their tax advisers regarding the creditability of foreign taxes in their particular circumstances. In lieu of claiming a foreign tax credit, U.S. Holders may, at their election, deduct foreign taxes, including any Swiss income tax, in computing their taxable income, subject to generally applicable limitations under U.S. law. An election to deduct foreign taxes instead of claiming foreign tax credits applies to all foreign taxes paid or accrued in the taxable year.

Sale or Other Disposition of Common Shares

Gain or loss realized by a U.S. Holder on the sale or other disposition of common shares will be capital gain or loss, and will be long-term capital gain or loss if the U.S. Holder’s holding period for such common shares was more than one year as of the date of the sale or other disposition. The amount of the gain or loss will equal the difference between the U.S. Holder’s tax basis in the common shares disposed of and the amount realized on the disposition, in each case as determined in U.S. dollars. Long-term capital gain recognized by a non-corporate U.S. Holder is subject to U.S. federal income tax at rates lower than the rates applicable to ordinary income and short-term capital gains, while short-term capital gains are subject to U.S. federal income tax at the rates applicable to ordinary income. This gain or loss will generally be U.S.-source gain or loss for foreign tax credit purposes. However, U.S. Holders that are eligible for benefits under the Treaty may be able to elect to treat the gain as foreign-source income under the Treaty and claim a foreign tax credit in respect of Swiss taxes on disposition gains. The Foreign Tax Credit Regulations generally preclude a U.S. Holder from claiming a foreign tax credit with respect to Swiss income taxes on gains from dispositions of common shares if the U.S. Holder does not elect to apply the benefits of the Treaty. However, in that case it is possible that any Swiss taxes on disposition gains may either be deductible or reduce the amount realized on the disposition. The rules governing foreign tax credits and deductibility of foreign taxes are complex. U.S. Holders should consult their tax advisers regarding their eligibility for benefits under the Treaty and the consequences of the imposition of any Swiss tax on disposition gains. The deductibility of capital losses is subject to various limitations.

Passive Foreign Investment Company Rules

Under the Code, we will be a PFIC for any taxable year in which, after the application of certain look-through rules with respect to subsidiaries, either (i) 75% or more of our gross income consists of “passive income” or (ii) 50% or more of the average quarterly value of our assets consist of assets that produce, or are held for the production of, “passive income.” For purposes of the above calculations, we will be treated as if we hold our proportionate share of the assets of, and receive directly our proportionate share of the income of, any other corporation in which we directly or indirectly own at least 25%, by value, of the shares of such corporation. Passive income generally includes interest, dividends, certain non-active rents and royalties, and capital gains.

Based on the information available to us as of the date of this prospectus supplement, we believe that we were not a PFIC for our 2022 taxable year. Whether we are a PFIC in any year, or will become a PFIC in any future year, is uncertain because, among other things, (i) we currently own, and likely will continue to own, a substantial amount of passive assets, including cash, (ii) the timing of our recognition of active income for U.S. federal income tax purposes, which may differ from the timing of the recognition of such income for financial accounting purposes, may result in our recognizing minimal amounts of active income for U.S. federal income tax purposes in certain taxable years and (iii) the valuation of our assets that generate non-passive income for PFIC purposes, including our intangible assets, is uncertain and may be determined in substantial part by our market capitalization, which may vary substantially over time. Accordingly, there can be no assurance that we will not be a PFIC for any future taxable year.

If we are a PFIC for any year during which a U.S. Holder holds common shares, we will continue to be treated as a PFIC with respect to that U.S. Holder for all succeeding years during which the U.S. Holder holds common shares, even if we cease to meet the threshold requirements for PFIC status, unless the U.S. Holder elects to recognize gain, if any, as if it sold its common shares as of the last day of the last tax year in which we are a PFIC (such election, a “Purging Election”). In addition, the Company may, directly or indirectly, have held or hold equity interests in other PFICs (collectively, “Lower-tier PFICs”). Under attribution rules, if the Company is a PFIC, U.S. Holders will be deemed to own their proportionate shares of the stock of Lower-tier PFICs and will be subject to U.S. federal income tax according to the rules described in the following paragraphs on (i) certain distributions by a Lower-tier PFIC and (ii) a disposition of shares of a Lower-tier PFIC, in each case as if the U.S. Holder held such shares directly, even though holders have not received the proceeds of those distributions or dispositions directly. U.S. Holders should consult their tax advisers about the consequences to them if we own one or more Lower-tier PFICs.

If we are a PFIC for any taxable year during which a U.S. Holder holds common shares (assuming such U.S. Holder has not made certain elections, as described below), gain recognized by the U.S. Holder on

sale or other disposition (including certain pledges) of common shares (including any gain recognized as a consequence of a Purging Election) will be allocated ratably over the U.S. Holder’s holding period for the common shares. The amounts allocated to the taxable year of the sale or other disposition and to any year before we became a PFIC will be taxed as ordinary income. The amount allocated to each other taxable year will be subject to tax at the highest rate in effect for individuals or corporations, as appropriate, for that taxable year, and an interest charge will be imposed on the resulting tax liability. Further, to the extent that any distribution received by a U.S. Holder on its common shares exceeds 125% of the average of the annual distributions on the common shares received during the preceding three years or the U.S. Holder’s holding period, whichever is shorter, that distribution will be subject to taxation in the same manner as gain, described immediately above. Certain elections may be available (including a mark-to-market election) that may provide alternative tax treatments. U.S. Holders should consult their tax advisors regarding whether any of these elections for alternative treatment would be available and, if so, what the consequences of the alternative treatments would be in their particular circumstances.

If we are a PFIC (or, with respect to a particular U.S. Holder, are treated as a PFIC) for a taxable year in which we pay a dividend or for the prior taxable year, the preferential dividend rates discussed above with respect to dividends paid to certain non-corporate U.S. Holders will not apply.

If we were a PFIC for any taxable year during which a U.S. Holder holds common shares, the U.S. Holder would generally be required to file an annual report on IRS Form 8621 with their annual U.S. federal income tax returns, subject to certain exceptions.

Prospective U.S. Holders should consult their tax advisers regarding the potential PFIC rules to an investment in common shares.

Information Reporting and Backup Withholding

Payments of dividends and sales proceeds that are made within the United States or through certain U.S.-related financial intermediaries generally are subject to information reporting, and may be subject to backup withholding, unless (i) the U.S. Holder is a corporation or other exempt recipient or (ii) in the case of backup withholding, the U.S. Holder provides a correct taxpayer identification number and certifies that it is not subject to backup withholding.

The amount of any backup withholding from a payment to a U.S. Holder will be allowed as a credit against the U.S. Holder’s U.S. federal income tax liability and may entitle it to a refund, provided that the required information is timely furnished to the IRS.

PLAN OF DISTRIBUTION

We previously entered into a sales agreement with Jefferies, under which we may offer and sell our common shares from time to time through Jefferies, acting as agent. Pursuant to this prospectus supplement and accompanying prospectus, we may offer and sell up to $150,000,000 of our common shares. Sales of our common shares, if any, under this prospectus supplement and the accompanying prospectus will be made by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act.

Each time we wish to issue and sell common shares under the sales agreement, we will notify Jefferies of the number of common shares to be sold, the dates on which such sales are anticipated to be made, any limitation on the number of common shares to be sold in any one day and any minimum price below which sales may not be made. Once we have so instructed Jefferies, unless Jefferies declines to accept the terms of such notice, Jefferies has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such common shares up to the amount specified on such terms. The obligations of Jefferies under the sales agreement to sell our common shares are subject to a number of conditions that we must meet.

The settlement of sales of our common shares between us and Jefferies is generally anticipated to occur on the second trading day following the date on which the sale was made. Sales of our common shares as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and Jefferies may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay Jefferies a commission up to 3.0% of the aggregate gross proceeds we receive from each sale of our common shares. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. Except as we and Jefferies otherwise agree, we will reimburse Jefferies for the fees and disbursements of its counsel, payable upon execution of the sales agreement, in an amount not to exceed $100,000, in addition to certain ongoing disbursements of its legal counsel unless we and Jefferies otherwise agree. We estimate that the total expenses for the offering, excluding any commissions or expense reimbursement payable to Jefferies under the terms of the sales agreement, will be approximately $2.5 million. The remaining proceeds, after deducting any other transaction fees, will equal our net proceeds from the sale of our common shares in this offering.

Jefferies will provide written confirmation to us before the open on the NYSE on the day following each day on which common shares are sold under the sales agreement. Each confirmation will include the number of common shares sold on that day, the aggregate gross proceeds of such sales and the proceeds to us.

In connection with the sale of common shares on our behalf, Jefferies will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Jefferies will be deemed to be underwriting commissions or discounts. We have agreed to indemnify Jefferies against certain liabilities, including civil liabilities under the Securities Act. We have also agreed to contribute to payments Jefferies may be required to make in respect of such liabilities.

The offering of our common shares pursuant to the sales agreement will terminate upon the earlier of (i) the sale of all common shares subject to the sales agreement and (ii) the termination of the sales agreement as permitted therein.

This summary of the material provisions of the sales agreement does not purport to be a complete statement of its terms and conditions. A copy of the sales agreement is filed as an exhibit to the registration statement of which this prospectus supplement forms a part.

Jefferies and its affiliates may in the future provide various investment banking, commercial banking, financial advisory and other financial services for us and our affiliates, for which services they may in the future receive customary fees. In the course of its business, Jefferies may actively trade our securities for

its own account or for the accounts of customers, and, accordingly, Jefferies may at any time hold long or short positions in such securities.

A prospectus supplement and the accompanying prospectus in electronic format may be made available on a website maintained by Jefferies, and Jefferies may distribute the prospectus supplement and the accompanying prospectus electronically. The address of Jefferies LLC is 520 Madison Avenue, New York, NY 10022.

LEGAL MATTERS

The validity of the common shares offered and certain other matters with respect to Swiss law will be passed upon for us by Homburger AG, Zurich, Switzerland. Certain matters with respect to U.S. federal and New York State law will be passed upon for us by Davis Polk & Wardwell LLP, New York, New York. Jefferies LLC is represented in connection with this offering by Cooley LLP, New York, New York with respect to matters of U.S. federal law and by Lenz & Staehelin, Geneva, Switzerland, with respect to matters of Swiss law.

EXPERTS

The consolidated financial statements and management’s assessment of the effectiveness of internal control over ‎financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) ‎incorporated in this prospectus by reference to the Annual Report on Form 20-F for the year ended December 31, ‎‎2022 have been so incorporated in reliance on the report of PricewaterhouseCoopers SA, an independent registered ‎public accounting firm, given on the authority of said firm as experts in auditing and accounting. ‎PricewaterhouseCoopers SA is a member of EXPERTsuisse — Swiss Expert Association for Audit, Tax and ‎Fiduciary.‎

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational requirements of the Exchange Act. Accordingly, we are required to file reports and other information with the SEC, including annual reports on Form 20-F and reports on Form 6-K. The SEC maintains an Internet site at www.sec.gov that contains reports, proxy and information statements and other information we have filed electronically with the SEC. As a foreign private issuer, we are exempt under the Exchange Act from, among other things, the rules prescribing the furnishing and content of proxy statements, and our executive officers, directors and principal shareholders are exempt from the reporting and short-swing profit recovery provisions contained in Section 16 of the Exchange Act. In addition, we are not required under the Exchange Act to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. companies whose securities are registered under the Exchange Act.

We have filed with the SEC a “shelf” registration statement (including amendments and exhibits to the registration statement) on Form F-3 under the Securities Act. This prospectus supplement, which is part of the registration statement, does not contain all of the information set forth in the registration statement and the exhibits and schedules to the registration statement. We have omitted parts of the registration statement in accordance with the rules and regulations of the SEC. For more detail about us and the securities offered by this prospectus supplement, you may examine the registration statement on Form F-3 and the exhibits filed with it at the website provided in the previous paragraph.

We maintain a corporate website at www.adctherapeutics.com. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus supplement or the registration statement of which it forms a part.

INFORMATION INCORPORATED BY REFERENCE

The rules of the SEC allow us to incorporate by reference information in this prospectus, which means that we disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference in this prospectus supplement is considered to be a part of this prospectus supplement. Any statement made in this prospectus supplement or in a document incorporated or deemed to be incorporated by reference in this prospectus supplement will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement or in any other subsequently filed document that is also incorporated or deemed to be incorporated by reference in this prospectus supplement modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement. This prospectus supplement incorporates by reference the documents listed below:

All subsequent annual reports on Form 20-F, Form 40-F or Form 10-K that we file with the SEC and all subsequent filings on Forms 10-Q and 8-K filed by us with the SEC pursuant to the Exchange Act (excluding, in each case, any information or documents deemed to be furnished and not filed with the SEC), after the date hereof and prior to the completion or termination of this offering, shall be incorporated by reference. We may incorporate by reference any reports on Form 6-K that we furnish to the SEC that we specifically identify in such form as being incorporated by reference into this prospectus supplement after (i) after the filing of the registration statement of which the accompanying prospectus forms a part and prior to the effectiveness of such registration statement and (ii) after the date of this prospectus supplement and prior to the completion or termination of the offering of securities under this prospectus supplement.

You can obtain any of the filings incorporated by reference in this prospectus supplement through us or from the SEC through the SEC’s website at www.sec.gov. Our filings with the SEC, including our Annual Reports on Form 20-F and Reports on Form 6-K and exhibits incorporated in and amendments to those reports, are also available free of charge on our website (www.adctherapeutics.com) as soon as reasonably practicable after they are filed with, or furnished to, the SEC. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus supplement or the registration statement of which it forms a part. We will provide to each person, including any beneficial owner, to whom this prospectus is delivered, a copy of any or all the reports or documents incorporated by reference in this prospectus supplement at no cost, upon written or oral request to us at the following address:

Investor Relations
ADC Therapeutics SA
c/o ADC Therapeutics America, Inc.
430 Mountain Avenue, 4th Floor
Murray Hill, NJ 07974
(908) 546-5556

ADC THERAPEUTICS SA

Up to $150,000,000

Common Shares

PROSPECTUS

Jefferies

           , 2023

PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Under Swiss law, a corporation may indemnify its directors or officers against losses and expenses (except for such losses and expenses arising from willful misconduct or negligence, although legal scholars advocate that at least gross negligence be required), including attorney’s fees, judgments, fines and settlement amounts actually and reasonably incurred in a civil or criminal action, suit or proceeding by reason of having been the representative of, or serving at the request of, the corporation.

Subject to Swiss law, our articles of association provide for indemnification of the existing and former members of our board of directors and our executive committee as well as their heirs, executors and administrators, against liabilities arising in connection with the performance of their duties in such capacity, and our articles of association require us to advance the expenses of defending any action, suit or proceeding to existing and former members of our board of directors and our executive committee to the extent not included in insurance coverage or advanced by third parties.

In addition, under general principles of Swiss employment law, an employer may be required to indemnify an employee against losses and expenses incurred by such employee in the proper execution of their duties under the employment agreement with the company.

We have entered into indemnification agreements with each of the members of our board of directors and executive officers.

Insofar as indemnification for liabilities arising under the Securities Act of 1933, as amended (the “Securities Act”) may be permitted to directors, officers and controlling persons of the Company, the Company has been advised that, in the opinion of the U.S. Securities and Exchange Commission (the “SEC”), such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable.

The exhibit index attached hereto is incorporated herein by reference.

The undersigned hereby undertakes:

(1)     to include any prospectus required by section 10(a)(3) of the Securities Act;

(2)     to reflect in the prospectus any facts or events arising after the effective date of this registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(3)     to include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1), (a)(2) and (a)(3) of this section do not apply if the registration statement is on Form S-3 or Form F-3 and the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(1)     each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(2)     each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date; and

(1)     any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(2)     any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(3)     the portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(4)     any other communication that is an offer in the offering made by the undersigned registrant to the purchaser;

The undersigned hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that, in the opinion of the SEC, such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer, or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless, in the opinion of its counsel, the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question of whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

The undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under Section 310(a) of the Trust Indenture Act (“Trust Indenture Act”) in accordance with the rules and regulations prescribed by the Commission under Section 305(b)(2) of the Trust Indenture Act.

EXHIBIT INDEX

The following documents are filed as part of this registration statement:

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “Securities Act”), the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form F-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the municipality of Epalinges, Switzerland on March 15, 2023.

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Ameet Mallik, Jose “Pepe” Carmona and Peter J. Graham and each of them, individually, as his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him and in his name, place and stead in any and all capacities, in connection with this registration statement, including to sign in the name and on behalf of the undersigned, this registration statement and any and all amendments thereto, including post-effective amendments and registrations filed pursuant to Rule 462 under the Securities Act, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the U.S. Securities and Exchange Commission, granting unto such attorneys-in-fact and agents full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or his substitute, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act, this registration statement has been signed by the following persons on March 15, 2023 in the capacities indicated: