scPharmaceuticals (SCPH) 10-Q9 Nov 222022 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2022	Nov. 08, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Trading Symbol	SCPH
Entity Registrant Name	SCPHARMACEUTICALS INC.
Entity Central Index Key	0001604950
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-38293
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5184075
Entity Address, Address Line One	2400 District Avenue
Entity Address, Address Line Two	Suite 310
Entity Address, City or Town	Burlington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01803
City Area Code	617
Local Phone Number	517-0730
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		27,434,083

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 41,289	$ 74,268
Restricted cash		182
Short-term investments	3,897	1,010
Prepaid expenses	1,643	2,791
Other current assets	340	24
Total current assets	47,169	78,275
Restricted cash	182
Property and equipment, net	62	69
Right-of-use lease assets - operating, net	677	410
Deposits and other assets	310	283
Total assets	48,400	79,037
Current liabilities
Accounts payable	996	544
Accrued expenses	5,178	3,995
Term loan, short-term	9,880	9,805
Lease obligation - operating, short-term	594	476
Other current liabilities	528	26
Total current liabilities	17,176	14,846
Term loan, long-term		7,354
Lease obligation - operating, long-term	114
Other liabilities		367
Total liabilities	17,290	22,567
Commitments and contingencies (Note 11)
Stockholders’ equity
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.0001 par value; 150,000,000 shares authorized as of September 30, 2022; 27,366,707 and 27,402,121 shares issued and outstanding as of December 31, 2021 and September 30, 2022, respectively	3	3
Additional paid-in capital	248,395	246,166
Accumulated deficit	(217,288)	(189,698)
Accumulated other comprehensive loss		(1)
Total stockholders’ equity	31,110	56,470
Total liabilities and stockholders’ equity	$ 48,400	$ 79,037

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	27,402,121	27,366,707
Common stock, shares outstanding	27,402,121	27,366,707

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating expenses:
Research and development	$ 3,718	$ 3,694	$ 13,207	$ 11,509
General and administrative	6,277	2,211	13,448	7,593
Total operating expenses	9,995	5,905	26,655	19,102
Loss from operations	(9,995)	(5,905)	(26,655)	(19,102)
Other income (expense)	(22)	10	55	298
Interest income	232	10	353	42
Interest expense	(377)	(667)	(1,343)	(1,954)
Net loss	$ (10,162)	$ (6,552)	$ (27,590)	$ (20,716)
Net loss per share - basic	$ (0.37)	$ (0.24)	$ (1.01)	$ (0.76)
Net loss per share - diluted	$ (0.37)	$ (0.24)	$ (1.01)	$ (0.76)
Weighted average common shares outstanding - basic	27,401,060	27,355,454	27,382,760	27,349,279
Weighted average common shares outstanding - diluted	27,401,060	27,355,454	27,382,760	27,349,279
Other comprehensive loss:
Unrealized gain on short-term investments	$ 7		$ 1
Comprehensive loss	$ (10,155)	$ (6,552)	$ (27,589)	$ (20,716)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Other Comprehensive Income
Beginning Balance at Dec. 31, 2020	$ 82,170	$ 3	$ 243,830	$ (161,664)	$ 1
Beginning Balance, Shares at Dec. 31, 2020		27,325,959
Net loss	(7,102)			(7,102)
Issuance of common stock upon exercise of stock options	9		9
Issuance of common stock upon exercise of stock options, Shares		2,500
Vesting of restricted stock	(81)		(81)
Vesting of restricted stock, Shares		26,994
Stock-based compensation	521		521
Unrealized gain (loss) on short-term investments	(2)				(2)
Ending Balance at Mar. 31, 2021	75,515	$ 3	244,279	(168,766)	(1)
Ending Balance, Shares at Mar. 31, 2021		27,355,453
Beginning Balance at Dec. 31, 2020	82,170	$ 3	243,830	(161,664)	1
Beginning Balance, Shares at Dec. 31, 2020		27,325,959
Net loss	(20,716)
Ending Balance at Sep. 30, 2021	63,110	$ 3	245,487	(182,380)
Ending Balance, Shares at Sep. 30, 2021		27,355,454
Beginning Balance at Mar. 31, 2021	75,515	$ 3	244,279	(168,766)	(1)
Beginning Balance, Shares at Mar. 31, 2021		27,355,453
Net loss	(7,062)			(7,062)
Issuance of common stock upon exercise of stock options, Shares		1
Stock-based compensation	589		589
Unrealized gain (loss) on short-term investments	1				1
Ending Balance at Jun. 30, 2021	69,043	$ 3	244,868	(175,828)
Ending Balance, Shares at Jun. 30, 2021		27,355,454
Net loss	(6,552)			(6,552)
Stock-based compensation	619		619
Ending Balance at Sep. 30, 2021	63,110	$ 3	245,487	(182,380)
Ending Balance, Shares at Sep. 30, 2021		27,355,454
Beginning Balance at Dec. 31, 2021	56,470	$ 3	246,166	(189,698)	(1)
Beginning Balance, Shares at Dec. 31, 2021		27,366,707
Net loss	(7,731)			(7,731)
Issuance of common stock upon exercise of stock options	21		21
Issuance of common stock upon exercise of stock options, Shares		4,781
Stock-based compensation	636		636
Unrealized gain (loss) on short-term investments	(3)				(3)
Ending Balance at Mar. 31, 2022	49,393	$ 3	246,823	(197,429)	(4)
Ending Balance, Shares at Mar. 31, 2022		27,371,488
Beginning Balance at Dec. 31, 2021	56,470	$ 3	246,166	(189,698)	(1)
Beginning Balance, Shares at Dec. 31, 2021		27,366,707
Net loss	$ (27,590)
Issuance of common stock upon exercise of stock options, Shares	11,756
Unrealized gain (loss) on short-term investments	$ 1
Ending Balance at Sep. 30, 2022	31,110	$ 3	248,395	(217,288)
Ending Balance, Shares at Sep. 30, 2022		27,402,121
Beginning Balance at Mar. 31, 2022	49,393	$ 3	246,823	(197,429)	(4)
Beginning Balance, Shares at Mar. 31, 2022		27,371,488
Net loss	(9,697)			(9,697)
Issuance of common stock through employee stock purchase plan	84		84
Issuance of common stock through employee stock purchase plan, Shares		23,658
Stock-based compensation	680		680
Unrealized gain (loss) on short-term investments	(3)				(3)
Ending Balance at Jun. 30, 2022	40,457	$ 3	247,587	(207,126)	(7)
Ending Balance, Shares at Jun. 30, 2022		27,395,146
Net loss	(10,162)			(10,162)
Issuance of common stock upon exercise of stock options	23		23
Issuance of common stock upon exercise of stock options, Shares		6,975
Stock-based compensation	785		785
Unrealized gain (loss) on short-term investments	7				$ 7
Ending Balance at Sep. 30, 2022	$ 31,110	$ 3	$ 248,395	$ (217,288)
Ending Balance, Shares at Sep. 30, 2022		27,402,121

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities
Net loss	$ (27,590,000)	$ (20,716,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	28,000	26,000
Amortization expense - right-of-use leased assets - operating	320,000	301,000
Accretion of discount (premium) on investments	(40,000)	120,000
Stock-based compensation	2,101,000	1,729,000
Non-cash interest expense	309,000	410,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	804,000	941,000
Accounts payable, accrued expenses and other liabilities	1,328,000	(2,864,000)
Net cash used in operating activities	(22,740,000)	(20,053,000)
Cash flows from investing activities
Purchases of property and equipment	(21,000)	(10,000)
Maturities of short-term investments	17,800,000	36,650,000
Purchases of short-term investments	(20,646,000)	(9,011,000)
Net cash provided by (used in) investing activities	(2,867,000)	27,629,000
Cash flows from financing activities
Principal payments on term loan	(7,500,000)
Proceeds from employee stock purchase plan	84,000
Proceeds from the exercise of vested stock options	44,000	9,000
Settlements of restricted stock units for tax withholding obligations		(81,000)
Net cash used in financing activities	(7,372,000)	(72,000)
Net increase (decrease) in cash, cash equivalents and restricted cash	(32,979,000)	7,504,000
Cash, cash equivalents and restricted cash at beginning of period	74,450,000	72,001,000
Cash, cash equivalents and restricted cash at end of period	41,471,000	79,505,000
Supplemental cash flow information
Interest paid	1,099,000	1,550,000
Taxes paid	$ 114,000	$ 166,000

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
Description of Business and Basis of Presentation	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business scPharmaceuticals LLC was formed as a limited liability company under the laws of the State of Delaware on February 19, 2013. On March 24, 2014, scPharmaceuticals LLC was converted to a Delaware corporation and changed its name to scPharmaceuticals Inc. (“the Company”). The Company is a pharmaceutical company focused on developing and commercializing products that have the potential to optimize the delivery of infused therapies, advance patient care and reduce healthcare costs. The Company’s strategy is designed to enable the subcutaneous administration of therapies that have previously been limited to intravenous (“IV”) delivery. The Company’s headquarters and primary place of business is Burlington, Massachusetts. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and have been prepared on a basis which assumes that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The condensed consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary, scPharmaceuticals Securities Corporation. Certain information and disclosures normally included in financial statements in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and related notes for the year ended December 31, 2021 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 22, 2022. The Company has determined that it operates in one segment. The accompanying condensed consolidated balance sheet as of September 30, 2022, the condensed consolidated statements of operations and comprehensive loss and stockholders’ equity for the three and nine months ended September 30, 2021 and 2022 and condensed consolidated statements of cash flows for the nine months ended September 30, 2021 and 2022 are unaudited. The unaudited condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare the Company’s audited annual financial statements and include, in the opinion of management, adjustments, consisting of normal recurring items, necessary for the fair statement of the condensed consolidated financial statements. The operating results for the three and nine months ended September 30, 2022 are not necessarily indicative of the results expected for the full year ending December 31, 2022. Liquidity As of September 30, 2022, the Company had an accumulated deficit of approximately $ 217.3 million. Management expects to continue to incur operating losses for the foreseeable future. The Company has financed its operations to date from proceeds from the sale of common stock, preferred stock and the incurrence of debt. As of September 30, 2022 , the Company had cash, cash equivalents, restricted cash, and short-term investments of $ 45.4 million. On October 13, 2022 (the “Closing Date”), the Company entered into a Credit Agreement and Guaranty (the "Oaktree Agreement") with, among others, the lenders from time to time party thereto (the "Lenders") and Oaktree Fund Administration, LLC, in its capacity as administrative agent for the Lenders (Note 12). The Company's existing cash, cash equivalents, restricted cash and short-term investments, along with proceeds from the Oaktree Agreement, will be sufficient to meet its cash commitments for at least the next 12 months after the date that the interim condensed consolidated financial statements are issued. Additionally, the Company expects to have access to funds pursuant to an at-the-market offering program with Cowen and Company, LLC (Note 9), or could otherwise seek additional funding through a combination of public or private equity offerings if it believes additional resources are needed. Additional financing may not be available on a timely basis on terms acceptable to the Company, or at all.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Sep. 30, 2022
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported periods. Actual results could differ from those estimates. Cash, Cash Equivalents and Restricted Cash Cash, cash equivalents and restricted cash consists of bank deposits and money market accounts with financial institutions. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. As of September 30, 2022 , the Company classified $ 182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, September 30, Cash and cash equivalents $ 74,268 $ 41,289 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 74,450 $ 41,471 Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash and cash equivalents and short-term investments. The Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes that such funds are subject to minimal credit risk. The Company’s short-term investments consist of United States Treasury securities and commercial paper. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment and requires all investments held by the Company to hold a minimum rating, thereby reducing credit risk exposure. Investments The Company invests excess cash balances in available-for-sale debt securities. The Company determines the appropriate classification of these securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company reports available-for-sale investments at fair value at each balance sheet date and includes any unrealized gains and losses in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense). If any adjustment to fair value reflects a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary,” including the intention to sell and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss. Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long-term lease obligations on the Company’s balance sheets. ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU lease asset excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes. Deferred tax assets and liabilities are recorded to reflect the impact of temporary differences between amounts of assets and liabilities for financial reporting purposes and such amounts as measured under enacted tax laws. A valuation allowance is required to offset any net deferred tax assets if, based upon the available evidence, it is more likely than not that some or all of the deferred tax asset will not be realized. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is “more likely than not” to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. At September 30, 2022 , the Company had no such accruals. As part of the Tax Cuts and Jobs Act of 2017 (TCJA), beginning with the Company’s fiscal year ending December 31, 2022, the Company is required to capitalize research and development expenses, as defined under section 174 of the Internal Revenue Code of 1986, as amended. For expenses that are incurred for research and development in the United States, the amounts will be amortized over 5 years, and expenses that are incurred for research and experimentation outside the United States will be amortized over 15 years. The Company already capitalizes its research and development expenses for income tax purposes as it is a start-up company, so there is no material impact forecasted for this change in legislation in 2022.

Net Loss per Share

Net Loss per Share	9 Months Ended
Net Loss per Share	Sep. 30, 2022
Earnings Per Share [Abstract]
Net Loss per Share	3. Net Loss per Share Net Loss per Share Attributable to Common Stockholders The following table sets forth the computation of basic and diluted net loss per share of common stock (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2021 2022 2021 2022 Net loss $ ( 6,552 ) $ ( 10,162 ) $ ( 20,716 ) $ ( 27,590 ) Weighted-average shares used in computing net loss per share 27,355,454 27,401,060 27,349,279 27,382,760 Net loss per share, basic and diluted $ ( 0.24 ) $ ( 0.37 ) $ ( 0.76 ) $ ( 1.01 ) The Company’s potentially dilutive securities, which include stock options and unvested restricted stock units, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect. Three Months Ended September 30, Nine Months Ended September 30, 2021 2022 2021 2022 Stock options to purchase common stock 2,677,743 3,864,895 2,677,743 3,864,895 Unvested restricted stock units 42,250 42,250 42,250 42,250 Total 2,719,993 3,907,145 2,719,993 3,907,145

Investments

Investments	9 Months Ended
Investments	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Investments	4. Investments Cash in excess of the Company’s immediate requirements is invested in accordance with the Company’s investment policy that primarily seeks to maintain adequate liquidity and preserve capital. A summary of the Company’s available-for-sale classified investments as of December 31, 2021 and September 30, 2022 consisted of the following (in thousands): At December 31, 2021 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value Corporate debt securities $ 1,011 $ - $ ( 1 ) $ 1,010 Total $ 1,011 $ - $ ( 1 ) $ 1,010 At September 30, 2022 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value United States Treasury securities $ 2,000 $ - $ - $ 2,000 Commercial paper 1,897 - - 1,897 Total $ 3,897 $ - $ - $ 3,897 The amortized cost and fair value of the Company’s available-for-sale investments, by contract maturity, as of September 30, 2022 consisted of the following (in thousands): Amortized Cost Fair Value Due in one year or less $ 3,897 $ 3,897 Total $ 3,897 $ 3,897

Property and Equipment

Property and Equipment	9 Months Ended
Property and Equipment	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment	5. Property and Equipment Purchased property and equipment consist of the following (dollars in thousands): ESTIMATED December 31, September 30, Office equipment 5 years $ 10 $ 6 Office furniture 7 years 126 126 Computer equipment 3 years 8 15 Leasehold improvements Life of lease 95 95 239 242 Less: Accumulated depreciation ( 170 ) ( 180 ) Property and equipment, net $ 69 $ 62 Depreciation expense for the three months ended September 30, 2021 and September 30, 2022 was $ 10,000 and $ 10,000 , respectively. Depreciation expense for the nine months ended September 30, 2021 and September 30, 2022 was $ 26,000 and $ 28,000 , respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
Accrued Expenses	Sep. 30, 2022
Accrued Liabilities, Current [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, September 30, Employee compensation and related costs $ 1,152 $ 2,137 Contract research and development 2,350 2,074 Consulting and professional service fees 265 591 Financing related costs 60 202 Interest 154 88 State taxes 5 — Other 9 86 Total accrued expenses $ 3,995 $ 5,178

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
Fair Value of Financial Instruments	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	7. Fair Value of Financial Instruments FASB ASC Topic, Fair Value Measurements and Disclosures (“ASC 820”), provides a fair value hierarchy, which classifies fair value measurements based on the inputs used in measuring fair value. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and observable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying values of the Company’s cash and restricted cash, prepaid expenses and deposits approximate their fair values due to their short-term nature. The carrying value of the Company’s loan payable is considered a reasonable estimate of fair value because the Company’s interest rate is near current market rates for instruments with similar characteristics. The following tables summarize the Company’s assets that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): As of December 31, 2021 TOTAL Quoted Prices Significant Significant Assets: Cash equivalents $ 72,449 $ 72,449 $ — $ — Total cash equivalents 72,449 72,449 — — Corporate debt securities 1,010 — 1,010 — Investments 1,010 — 1,010 — Total $ 73,459 $ 72,449 $ 1,010 $ — As of September 30, 2022 TOTAL Quoted Prices Significant Significant Assets: Cash equivalents $ 39,408 $ 39,408 $ — $ — Total cash equivalents 39,408 39,408 — — United States Treasury securities 2,000 2,000 — — Commercial paper 1,897 — 1,897 — Investments 3,897 2,000 1,897 — Total $ 43,305 $ 41,408 $ 1,897 $ —

Term Loan

Term Loan	9 Months Ended
Term Loan	Sep. 30, 2022
Debt Disclosure [Abstract]
Term Loan	8. Term Loan In May 2017, the Company entered into a loan and security agreement (the “2017 Loan Agreement”), with SLR Investment Corp. (f/k/a Solar Capital Ltd.) and Silicon Valley Bank (together, the “Lenders”), for $ 10.0 million. In September 2019, the Company replaced the 2017 Loan Agreement with a new $ 20.0 million term loan with the Lenders (the “2019 Loan Agreement”). The 2019 Loan Agreement extended the term of the credit facility until September 17, 2023 . Debt issuance costs for the 2019 Loan Agreement, including unamortized issuance costs for the 2017 Loan Agreement, were to be amortized to interest expense over the remaining term of the 2019 Loan Agreement using the effective-interest method. The interest rate under the 2019 Loan Agreement was the higher of (i) LIBOR plus 7.95 % or (ii) 10.18 % and there was an interest-only period until September 30, 2021. The rate at September 30, 2022 was 10.58 %. Pursuant to the 2019 Loan Agreement, the Company provided a first priority security interest in substantially all of the Company’s assets, including intellectual property, subject to certain exceptions. The Company entered into an Exit Agreement in connection with the 2019 Loan Agreement which provided for an aggregate payment of 4 % of the loan commitment, or $ 800,000 , to the lenders upon the occurrence of an exit event (the “Exit Fee”). The Company paid the Exit Fee during 2020 in conjunction with the Company’s public offering, which was deemed to be an exit event pursuant to the Exit Agreement. As of September 30, 2022 , unpaid borrowings under the 2019 Loan Agreement totaled $ 10.0 million. For the three and nine months ended September 30, 2022 , the Company recorded $ 66,000 and $ 221,000 , respectively, related to the amortization of debt discount associated with the 2019 Loan Agreement. For the three and nine months ended September 30, 2021 , the Company recorded $ 106,000 and $ 288,000 , respectively, related to the amortization of debt discount associated with the 2019 Loan Agreement. The 2019 Loan Agreement allowed the Company to voluntarily prepay all (but not less than all) of the outstanding principal at any time. A prepayment premium of 3 % or 1 % through the one-year anniversary and the two-year anniversary, respectively, would be assessed on the outstanding principal. After the two-year anniversary, a 0.5 % prepayment premium would be assessed on the outstanding principal. A final payment fee of $ 500,000 was due upon the earlier to occur of the maturity date or prepayment of such borrowings. For the three and nine months ended September 30, 2022 , the Company recorded $ 25,000 and $ 88,000 , respectively, related to the amortization of the final payment fee associated with the 2019 Loan Agreement. For the three and nine months ended September 30, 2021 , the Company recorded $ 41,000 and $ 122,000 , respectively, related to the amortization of the final payment fee associated with the 2019 Loan Agreement. In an event of default under the 2019 Loan Agreement, the interest rate would have been increased by 5 % and the balance under the loan may have become immediately due and payable at the option of the lenders. The 2019 Loan Agreement included restrictions on, among other things, the Company’s ability to incur additional indebtedness, change the name or location of the Company’s business, merge with or acquire other entities, pay dividends or make other distributions to holders of its capital stock, make certain investments, engage in transactions with affiliates, create liens, sell assets or pay subordinated debt. Total term loan and unamortized debt discount balances are as follows (in thousands): September 30, Face value $ 10,000 Less: discount ( 120 ) Total $ 9,880 Less: current portion ( 9,880 ) Long-term portion $ — As of September 30, 2022, future principal payments due under the 2019 Loan Agreement were as follows (in thousands): Year ended: December 31, 2022 $ 2,500 December 31, 2023 7,500 Total $ 10,000 In conjunction with the closing of the Oaktree Agreement (Note 12), the Company used a portion of the proceeds of the term loan to prepay all outstanding loans under the 2019 Loan Agreement, including the final payment fee, on the Closing Date.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2022
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity 2021 At-the-Market Issuance Sales Agreement On March 23, 2021, the Company entered into a Sales Agreement (the “2021 ATM Agreement”) with Cowen and Company, LLC (“Cowen”) with respect to an at-the-market offering program under which the Company could offer and sell shares of its common stock (the “2021 ATM Shares”), having an aggregate offering price of up to $ 50.0 million through Cowen as its sales agent. The Company agreed to pay Cowen a commission up to 3.0 % of the gross sales proceeds of such 2021 ATM Shares. As of September 30, 2022 , the Company had received no proceeds from the sale of shares of common stock pursuant to the 2021 ATM Agreement.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
Stock-Based Compensation	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation Stock Options The Company’s 2017 Stock Option and Incentive Plan (the “2017 Stock Plan”) became effective in November 2017 , upon the closing of the Company’s initial public offering and will expire in October 2027 . Under the 2017 Stock Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units (“RSUs”) and other stock-based awards. The Company’s 2014 Stock Incentive Plan (the “2014 Stock Plan”) was terminated in November 2017 effective upon the completion of the Company’s initial public offering and no further options will be granted under the 2014 Stock Plan. At September 30, 2022 , there were 598,619 options outstanding under the 2014 Stock Plan. As of September 30, 2022 , there were 6,136,901 shares of the Company’s common stock authorized for issuance under the 2017 Stock Plan, including 359,652 options that have been forfeited from the 2014 Stock Plan. At September 30, 2022 , there were 2,798,571 options available for issuance under the 2017 Stock Plan, 3,266,276 options outstanding and 42,250 RSUs outstanding. Awards granted under the 2017 Stock Plan have a term of ten years . Vesting of awards under the 2017 Stock Plan is determined by the board of directors, but is generally over one to four-year terms. The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions: Nine Months Ended 2021 2022 Risk-free interest rate 0.50 % - 0.88 % 1.67 % - 3.58 % Expected dividend yield 0 % 0 % Expected life 5.5 - 6.7 years 5.5 - 6.7 years Expected volatility 72 %- 74 % 70 %- 76 % Weighted-average grant date fair value $ 4.25 $ 3.02 The following table summarizes information about stock option activity during the nine months ended September 30, 2022 (in thousands, except share and per share data): NUMBER OF WEIGHTED- WEIGHTED- AGGREGATE Outstanding, December 31, 2021 2,662,752 $ 6.28 Granted 1,305,094 4.69 Exercised ( 11,756 ) 3.71 Forfeited ( 91,195 ) 6.77 Outstanding, September 30, 2022 3,864,895 $ 5.74 7.62 $ 5,044 Vested and exercisable, September 30, 2022 1,854,299 $ 6.20 6.18 $ 2,319 Vested and expected to vest, September 30, 2022 3,297,128 $ 5.81 7.38 $ 4,294 The following table summarizes information about RSU activity during the nine months ended September 30, 2022: RSUs AVERAGE GRANT Outstanding, December 31, 2021 42,250 $ 3.25 Granted — — Vested — — Forfeited — — RSUs outstanding at September 30, 2022 42,250 $ 3.25 Unrecognized compensation expense related to unvested options as of September 30, 2022 was $ 4.1 million and will be recognized over the remaining vesting periods of the underlying awards. The weighted-average period over which such compensation is expected to be recognized is 2.5 years. Unrecognized compensation expense related to unvested RSUs as of September 30, 2022 was $ 1,000 and will be recognized over the remaining vesting periods of the underlying awards. The weighted-average period over which such compensation is expected to be recognized is 1 month. Employee Stock Purchase Plan In October 2017, the board of directors approved the 2017 Employee Stock Purchase Plan ("the ESPP") which became effective in November 2017, upon the closing of the Company's IPO. As part of the ESPP, eligible employees may acquire an ownership interest in the Company by purchasing common stock, at a discount, through payroll deductions. Eligible employees who elected to participate were able to participate in the ESPP beginning September 1, 2021. During the nine months ended September 30, 2022 , 23,658 shares of common stock were issued under the ESPP. As of September 30, 2022 , there were 1,164,971 shares of common stock available for issuance under the ESPP. The Company recorded stock-based compensation expense in the following expense categories of its accompanying condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2022 (in thousands): Three Months Ended Nine Months Ended 2021 2022 2021 2022 Research and development $ 235 $ 263 $ 695 $ 781 General and administrative 384 522 1,034 1,320 Total $ 619 $ 785 $ 1,729 $ 2,101

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies Operating Leases The Company leases office facilities and equipment under long-term, non-cancelable operating lease agreements. The leases expire at various dates through 2025 and do not include renewal options. Certain leases provide for increases in future minimum annual rental payments as defined in the lease agreements. The leases generally also include real estate taxes and common area maintenance charges in the annual rental payments. Pursuant to the terms of its lease agreement for the Company’s headquarters, the Company obtained a letter of credit in the amount of approximately $ 182,000 as security on the lease obligation. The letter of credit is listed as restricted cash on the Company’s consolidated balance sheets. Short-term leases are leases having a term of twelve months or less. The Company recognizes short-term leases on a straight-line basis and does no t record a related lease asset or liability for such leases. The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of September 30, 2022 (in thousands): Year ended: December 31, 2022 $ 151 December 31, 2023 596 December 31, 2024 9 December 31, 2025 1 Total minimum lease payments 757 Less imputed interest ( 49 ) Total $ 708 Nine Months Ended 2021 2022 Lease cost: Operating lease cost $ 365 $ 376 Short-term lease cost 5 28 Sublease income ( 39 ) ( 39 ) Total lease cost $ 331 $ 365 Other information Cash paid for amounts included in the measurement of lease liabilities $ 396 $ 400 Operating cash flows from operating leases $ ( 43 ) $ ( 34 ) Weighted-average remaining lease term - operating leases 1.2 years 1.2 years Weighted-average discount rate - operating leases 10.1 % 10.1 % Research and Development Agreements As part of the Company’s research and development efforts, the Company enters into research and development agreements with certain companies. These agreements contain varying terms and provisions which include fees and milestones to be paid by the Company. Some of these agreements also contain provisions which require the Company to make payments for exclusivity in the development of products in the area of loop diuretics.

Subsequent Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2022
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. FDA Approval of FUROSCIX On October 10, 2022, the Company announced that the U.S. Food and Drug Administration (FDA) approved FUROSCIX® (furosemide injection), a proprietary formulation of furosemide delivered via West Pharmaceutical Services, Inc.'s on-body infusor for the treatment of congestion due to fluid overload in adults with New York Heart Association Class II/III chronic heart failure. Oaktree Financing On October 13, 2022, the Company entered into the Oaktree Agreement. The Oaktree Agreement establishes a $ 100.0 million term loan facility, consisting of (i) $ 50.0 million funded immediately, (ii) $ 25.0 million that the Company may borrow in up to two draws on or prior to September 30, 2024 and (iii) $ 25.0 million that the Company may borrow on or prior to December 31, 2024.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2022
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reported periods. Actual results could differ from those estimates.
Cash Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash, cash equivalents and restricted cash consists of bank deposits and money market accounts with financial institutions. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. As of September 30, 2022 , the Company classified $ 182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, September 30, Cash and cash equivalents $ 74,268 $ 41,289 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 74,450 $ 41,471
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash and cash equivalents and short-term investments. The Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes that such funds are subject to minimal credit risk. The Company’s short-term investments consist of United States Treasury securities and commercial paper. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment and requires all investments held by the Company to hold a minimum rating, thereby reducing credit risk exposure.
Investments	Investments The Company invests excess cash balances in available-for-sale debt securities. The Company determines the appropriate classification of these securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company reports available-for-sale investments at fair value at each balance sheet date and includes any unrealized gains and losses in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense). If any adjustment to fair value reflects a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary,” including the intention to sell and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss.
Leases	Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long-term lease obligations on the Company’s balance sheets. ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU lease asset excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes. Deferred tax assets and liabilities are recorded to reflect the impact of temporary differences between amounts of assets and liabilities for financial reporting purposes and such amounts as measured under enacted tax laws. A valuation allowance is required to offset any net deferred tax assets if, based upon the available evidence, it is more likely than not that some or all of the deferred tax asset will not be realized. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is “more likely than not” to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. At September 30, 2022 , the Company had no such accruals. As part of the Tax Cuts and Jobs Act of 2017 (TCJA), beginning with the Company’s fiscal year ending December 31, 2022, the Company is required to capitalize research and development expenses, as defined under section 174 of the Internal Revenue Code of 1986, as amended. For expenses that are incurred for research and development in the United States, the amounts will be amortized over 5 years, and expenses that are incurred for research and experimentation outside the United States will be amortized over 15 years. The Company already capitalizes its research and development expenses for income tax purposes as it is a start-up company, so there is no material impact forecasted for this change in legislation in 2022.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
Significant Accounting Policies (Tables)	Sep. 30, 2022
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	As of September 30, 2022 , the Company classified $ 182,000 as restricted cash related to a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate office facilities (Note 11). Cash, cash equivalents and restricted cash consists of the following (in thousands): December 31, September 30, Cash and cash equivalents $ 74,268 $ 41,289 Restricted cash 182 182 Cash, cash equivalents and restricted cash $ 74,450 $ 41,471

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
Net Loss per Share (Tables)	Sep. 30, 2022
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share of Common Stock	The following table sets forth the computation of basic and diluted net loss per share of common stock (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2021 2022 2021 2022 Net loss $ ( 6,552 ) $ ( 10,162 ) $ ( 20,716 ) $ ( 27,590 ) Weighted-average shares used in computing net loss per share 27,355,454 27,401,060 27,349,279 27,382,760 Net loss per share, basic and diluted $ ( 0.24 ) $ ( 0.37 ) $ ( 0.76 ) $ ( 1.01 )
Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share	The Company’s potentially dilutive securities, which include stock options and unvested restricted stock units, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect. Three Months Ended September 30, Nine Months Ended September 30, 2021 2022 2021 2022 Stock options to purchase common stock 2,677,743 3,864,895 2,677,743 3,864,895 Unvested restricted stock units 42,250 42,250 42,250 42,250 Total 2,719,993 3,907,145 2,719,993 3,907,145

Investments (Tables)

Investments (Tables)	9 Months Ended
Investments (Tables)	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Classified Investments	A summary of the Company’s available-for-sale classified investments as of December 31, 2021 and September 30, 2022 consisted of the following (in thousands): At December 31, 2021 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value Corporate debt securities $ 1,011 $ - $ ( 1 ) $ 1,010 Total $ 1,011 $ - $ ( 1 ) $ 1,010 At September 30, 2022 Investments - Current: Cost Basis Accumulated Unrealized Gains Accumulated Unrealized Losses Fair Value United States Treasury securities $ 2,000 $ - $ - $ 2,000 Commercial paper 1,897 - - 1,897 Total $ 3,897 $ - $ - $ 3,897
Summary of Amortized Cost and Fair Value of Available-for-Sale Investments by Contract Maturity	The amortized cost and fair value of the Company’s available-for-sale investments, by contract maturity, as of September 30, 2022 consisted of the following (in thousands): Amortized Cost Fair Value Due in one year or less $ 3,897 $ 3,897 Total $ 3,897 $ 3,897

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
Property and Equipment (Tables)	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Schedule of Purchased Property and Equipment	Purchased property and equipment consist of the following (dollars in thousands): ESTIMATED December 31, September 30, Office equipment 5 years $ 10 $ 6 Office furniture 7 years 126 126 Computer equipment 3 years 8 15 Leasehold improvements Life of lease 95 95 239 242 Less: Accumulated depreciation ( 170 ) ( 180 ) Property and equipment, net $ 69 $ 62

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
Accrued Expenses (Tables)	Sep. 30, 2022
Accrued Liabilities, Current [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, September 30, Employee compensation and related costs $ 1,152 $ 2,137 Contract research and development 2,350 2,074 Consulting and professional service fees 265 591 Financing related costs 60 202 Interest 154 88 State taxes 5 — Other 9 86 Total accrued expenses $ 3,995 $ 5,178

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
Fair Value of Financial Instruments (Tables)	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Summary of Assets Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s assets that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): As of December 31, 2021 TOTAL Quoted Prices Significant Significant Assets: Cash equivalents $ 72,449 $ 72,449 $ — $ — Total cash equivalents 72,449 72,449 — — Corporate debt securities 1,010 — 1,010 — Investments 1,010 — 1,010 — Total $ 73,459 $ 72,449 $ 1,010 $ — As of September 30, 2022 TOTAL Quoted Prices Significant Significant Assets: Cash equivalents $ 39,408 $ 39,408 $ — $ — Total cash equivalents 39,408 39,408 — — United States Treasury securities 2,000 2,000 — — Commercial paper 1,897 — 1,897 — Investments 3,897 2,000 1,897 — Total $ 43,305 $ 41,408 $ 1,897 $ —

Term Loan (Tables)

Term Loan (Tables)	9 Months Ended
Term Loan (Tables)	Sep. 30, 2022
Debt Disclosure [Abstract]
Schedule of Total Term Loan and Unamortized Debt Discount	Total term loan and unamortized debt discount balances are as follows (in thousands): September 30, Face value $ 10,000 Less: discount ( 120 ) Total $ 9,880 Less: current portion ( 9,880 ) Long-term portion $ —
Schedule of Future Principal Payments Due	As of September 30, 2022, future principal payments due under the 2019 Loan Agreement were as follows (in thousands): Year ended: December 31, 2022 $ 2,500 December 31, 2023 7,500 Total $ 10,000

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
Stock-Based Compensation (Tables)	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Estimated Fair Value of Options Valuation Assumptions	The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions: Nine Months Ended 2021 2022 Risk-free interest rate 0.50 % - 0.88 % 1.67 % - 3.58 % Expected dividend yield 0 % 0 % Expected life 5.5 - 6.7 years 5.5 - 6.7 years Expected volatility 72 %- 74 % 70 %- 76 % Weighted-average grant date fair value $ 4.25 $ 3.02
Summary of Information about Stock Option Activity	The following table summarizes information about stock option activity during the nine months ended September 30, 2022 (in thousands, except share and per share data): NUMBER OF WEIGHTED- WEIGHTED- AGGREGATE Outstanding, December 31, 2021 2,662,752 $ 6.28 Granted 1,305,094 4.69 Exercised ( 11,756 ) 3.71 Forfeited ( 91,195 ) 6.77 Outstanding, September 30, 2022 3,864,895 $ 5.74 7.62 $ 5,044 Vested and exercisable, September 30, 2022 1,854,299 $ 6.20 6.18 $ 2,319 Vested and expected to vest, September 30, 2022 3,297,128 $ 5.81 7.38 $ 4,294
Schedule of RSU Activity	The following table summarizes information about RSU activity during the nine months ended September 30, 2022: RSUs AVERAGE GRANT Outstanding, December 31, 2021 42,250 $ 3.25 Granted — — Vested — — Forfeited — — RSUs outstanding at September 30, 2022 42,250 $ 3.25
Summary of Stock-Based Compensation Expense	The Company recorded stock-based compensation expense in the following expense categories of its accompanying condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2022 (in thousands): Three Months Ended Nine Months Ended 2021 2022 2021 2022 Research and development $ 235 $ 263 $ 695 $ 781 General and administrative 384 522 1,034 1,320 Total $ 619 $ 785 $ 1,729 $ 2,101

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
Commitments and Contingencies (Tables)	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities	The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of September 30, 2022 (in thousands): Year ended: December 31, 2022 $ 151 December 31, 2023 596 December 31, 2024 9 December 31, 2025 1 Total minimum lease payments 757 Less imputed interest ( 49 ) Total $ 708
Schedule of Lease Cost and Other Information of Operating Lease Liabilities	Nine Months Ended 2021 2022 Lease cost: Operating lease cost $ 365 $ 376 Short-term lease cost 5 28 Sublease income ( 39 ) ( 39 ) Total lease cost $ 331 $ 365 Other information Cash paid for amounts included in the measurement of lease liabilities $ 396 $ 400 Operating cash flows from operating leases $ ( 43 ) $ ( 34 ) Weighted-average remaining lease term - operating leases 1.2 years 1.2 years Weighted-average discount rate - operating leases 10.1 % 10.1 %

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ (217,288)	$ (189,698)
Cash, cash equivalents, restricted cash, and short-term investments	$ 45,400

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2022 USD ($)
Schedule Of Accounting Policies [Line Items]
Restricted cash	$ 182,000
Potential interest and penalties associated with uncertain tax positions, accruals	$ 0
Amortized period for expenses incurred for research and development in united states	5 years
Amortized period for expenses incurred for research and development outside united states	15 years
Letter of Credit
Schedule Of Accounting Policies [Line Items]
Restricted cash	$ 182,000

Significant Accounting Polici_5

Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 41,289	$ 74,268
Restricted cash		182
Restricted cash	182
Cash, cash equivalents and restricted cash	$ 41,471	$ 74,450	$ 79,505	$ 72,001

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net loss	$ (10,162)	$ (6,552)	$ (27,590)	$ (20,716)
Weighted-average shares used in computing net loss per share, basic	27,401,060	27,355,454	27,382,760	27,349,279
Weighted-average shares used in computing net loss per share, diluted	27,401,060	27,355,454	27,382,760	27,349,279
Net loss per share, basic	$ (0.37)	$ (0.24)	$ (1.01)	$ (0.76)
Net loss per share, diluted	$ (0.37)	$ (0.24)	$ (1.01)	$ (0.76)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	3,907,145	2,719,993	3,907,145	2,719,993
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	3,864,895	2,677,743	3,864,895	2,677,743
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	42,250	42,250	42,250	42,250

Investments - Summary of Availa

Investments - Summary of Available-for-Sale Classified Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Cost Basis	$ 3,897	$ 1,011
Accumulated Unrealized Losses		(1)
Fair Value	3,897	1,010
United States Treasury Securities
Marketable Securities [Line Items]
Cost Basis	2,000
Fair Value	2,000
Corporate Debt Securities
Marketable Securities [Line Items]
Cost Basis		1,011
Accumulated Unrealized Losses		(1)
Fair Value		$ 1,010
Commercial Paper
Marketable Securities [Line Items]
Cost Basis	1,897
Fair Value	$ 1,897

Investments - Summary of Amorti

Investments - Summary of Amortized Cost and Fair Value of Available-for-Sale Investments by Contract Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 3,897
Amortized Cost, Total	3,897	$ 1,011
Fair Value, Due in one year or less	3,897
Fair Value, Total	$ 3,897	$ 1,010

Property and Equipment - Schedu

Property and Equipment - Schedule of Purchased Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 242	$ 239
Less: Accumulated depreciation	(180)	(170)
Property and equipment, net	$ 62	69
Office Equipment
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	5 years
Property and equipment, gross	$ 6	10
Office Furniture
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	7 years
Property and equipment, gross	$ 126	126
Computer Equipment
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	3 years
Property and equipment, gross	$ 15	8
Leasehold Improvements
Property Plant And Equipment [Line Items]
ESTIMATED USEFUL LIFE	Life of lease
Property and equipment, gross	$ 95	$ 95

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 10,000	$ 10,000	$ 28,000	$ 26,000

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accrued Liabilities, Current [Abstract]
Employee compensation and related costs	$ 2,137	$ 1,152
Contract research and development	2,074	2,350
Consulting and professional service fees	591	265
Financing related costs	202	60
Interest	88	154
State taxes		5
Other	86	9
Total accrued expenses	$ 5,178	$ 3,995

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets:
Cash equivalents	$ 39,408	$ 72,449
Investments	3,897	1,010
Total	43,305	73,459
United States Treasury Securities
Assets:
Investments	2,000
Corporate Debt Securities
Assets:
Investments		1,010
Commercial Paper
Assets:
Investments	1,897
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Cash equivalents	39,408	72,449
Investments	2,000
Total	41,408	72,449
Quoted Prices in Active Markets (Level 1) [Member] \| United States Treasury Securities
Assets:
Investments	2,000
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Investments	1,897	1,010
Total	1,897	1,010
Significant Other Observable Inputs (Level 2) [Member] \| Corporate Debt Securities
Assets:
Investments		$ 1,010
Significant Other Observable Inputs (Level 2) [Member] \| Commercial Paper
Assets:
Investments	$ 1,897

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - SLR Investment Corp. and Silicon Valley Bank - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	May 31, 2017
2017 Loan Agreement
Debt Instrument [Line Items]
Unpaid borrowings						$ 10,000,000
2019 Loan Agreement
Debt Instrument [Line Items]
Loan agreement, maturity date	Sep. 17, 2023
Debt instrument, interest rate terms				The interest rate under the 2019 Loan Agreement was the higher of (i) LIBOR plus 7.95% or (ii) 10.18%
Debt instrument, effective interest rate		10.58%		10.58%
Exit fee, percentage				4%
Exit fee				$ 800,000
Unpaid borrowings	$ 20,000,000	$ 10,000,000		10,000,000
Amortization of debt discount		66,000	$ 106,000	$ 221,000	$ 288,000
Prepayment premium percentage after year two				0.50%
Final payment fee				$ 500,000
Amortization of final payment fee		$ 25,000	$ 41,000	$ 88,000	$ 122,000
Increase in interest rate on default				5%
2019 Loan Agreement \| Minimum
Debt Instrument [Line Items]
Interest rate, minimum		10.18%		10.18%
Prepayment premium percentage two				0.01
2019 Loan Agreement \| Maximum
Debt Instrument [Line Items]
Prepayment premium percentage one				0.03
2019 Loan Agreement \| Libor
Debt Instrument [Line Items]
Basis spread on variable base rate				7.95%

Term Loan - Schedule of Total T

Term Loan - Schedule of Total Term Loan and Unamortized Debt Discount (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2019
Debt Instrument [Line Items]
Less: current portion	$ (9,880)	$ (9,805)
Long-term portion		$ 7,354
2019 Loan Agreement \| SLR Investment Corp. and Silicon Valley Bank
Debt Instrument [Line Items]
Loan and security agreement, amount	10,000		$ 20,000
Less: discount	(120)
Total	9,880
Less: current portion	$ (9,880)

Term Loan - Schedule of Future

Term Loan - Schedule of Future Principal Payments Due (Details) - 2019 Loan Agreement - SLR Investment Corp. and Silicon Valley Bank - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2019
Debt Instrument [Line Items]
December 31, 2022	$ 2,500
December 31, 2023	7,500
Total	$ 10,000	$ 20,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - 2021 ATM Agreement - Cowen - Common Stock - USD ($)		9 Months Ended
	Mar. 23, 2021	Sep. 30, 2022
Stockholders Equity Note [Line Items]
Proceeds from sale of shares,Net		$ 0
Maximum
Stockholders Equity Note [Line Items]
Aggregate offering price	$ 50,000,000
Percentage of commission on gross sales proceeds	3%

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	1,305,094
Stock option, number of shares outstanding	3,864,895	2,662,752
Unrecognized compensation expense	$ 4,100,000
Recognition period (in years)	2 years 6 months
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 1,000
Recognition period (in years)	1 month
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option and incentive plan effective date	Nov. 30, 2017
Stock option and incentive plan expiration date	Oct. 31, 2027
Stock option, number of shares outstanding	3,266,276
Number of common shares authorized for issuance	6,136,901
Stock options, available for issuance	2,798,571
Term of option granted	10 years
2017 Stock Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	1 year
2017 Stock Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term	4 years
2017 Stock Plan \| Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of restricted stock units outstanding	42,250
2014 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional options granted	0
Stock option and incentive plan expiration date	Nov. 30, 2017
Stock option, number of shares outstanding	598,619
Number of options forfeited	359,652
2017 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares issued	23,658
Number of common stock shares available for issuance	1,164,971

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Estimated Fair Value of Options Valuation Assumptions (Details) - $ / shares	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.67%	0.50%
Risk-free interest rate, maximum	3.58%	0.88%
Expected dividend yield	0%	0%
Expected volatility, minimum	70%	72%
Expected volatility, maximum	76%	74%
Weighted-average grant date fair value	$ 3.02	$ 4.25
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	6 years 8 months 12 days	6 years 8 months 12 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Information about Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2022
NUMBER OF SHARES
Number of shares outstanding, beginning balance	2,662,752
Additional options granted	1,305,094
Number of shares exercised	(11,756)
Number of shares forfeited	(91,195)
Number of shares outstanding, ending balance	3,864,895
Vested and exercisable, ending balance	1,854,299
Vested and expected to vest, ending balance	3,297,128
WEIGHTED-AVERAGE EXERCISE PRICE
Weighted average exercise prices, outstanding beginning balance	$ 6.28
Weighted average exercise prices, granted	4.69
Weighted average exercise prices, exercised	3.71
Weighted average exercise prices, forfeited	6.77
Weighted average exercise prices, outstanding ending balance	5.74
Weighted average exercise prices, vested and exercisable ending balance	6.20
Weighted average exercise prices, vested and expected to vest ending balance	$ 5.81
WEIGHTED-AVERAGE REMAINING CONTRACTUAL TERM
Weighted average remaining contractual term, outstanding	7 years 7 months 13 days
Weighted average remaining contractual term, vested and exercisable	6 years 2 months 4 days
Weighted average remaining contractual term, vested and expected to vest	7 years 4 months 17 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, outstanding ending balance	$ 5,044
Aggregate intrinsic value, vested and exercisable ending balance	2,319
Aggregate intrinsic value, vested and expected to vest ending balance	$ 4,294

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of RSU Activity (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Outstanding, December 31, 2021 \| shares	42,250
RSUs Granted \| shares	0
RSUs Vested \| shares	0
RSUs Forfeited \| shares	0
RSUs outstanding at September 30, 2022 \| shares	42,250
AVERAGE GRANT DATE FAIR VALUE, Outstanding, December 31, 2021 \| $ / shares	$ 3.25
AVERAGE GRANT DATE FAIR VALUE, Granted \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, Vested \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, Forfeited \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, RSUs outstanding at September 30, 2022 \| $ / shares	$ 3.25

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 785	$ 619	$ 2,101	$ 1,729
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	263	235	781	695
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 522	$ 384	$ 1,320	$ 1,034

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Commitments And Contingencies [Line Items]
Operating leases expire	2025
Restricted cash	$ 182,000
Short-term lease asset	677,000	$ 410,000
Short-term lease liability	594,000	$ 476,000
Short-term Leases Recognized on Straight-line Basis
Commitments And Contingencies [Line Items]
Short-term lease asset	0
Short-term lease liability	0
Letter of Credit
Commitments And Contingencies [Line Items]
Restricted cash	182,000
Letter of Credit \| Lease Agreement Require Standby Letter of Credit
Commitments And Contingencies [Line Items]
Restricted cash	$ 182,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Year ended:
December 31, 2022	$ 151
December 31, 2023	596
December 31, 2024	9
December 31, 2025	1
Total minimum lease payments	757
Less imputed interest	(49)
Total	$ 708

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Lease Cost and Other Information of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Lease cost:
Operating lease cost	$ 376	$ 365
Short-term lease cost	28	5
Sublease income	(39)	(39)
Total lease cost	365	331
Other information
Cash paid for amounts included in the measurement of lease liabilities	400	396
Operating cash flows from operating leases	$ (34)	$ (43)
Weighted-average remaining lease term - operating leases	1 year 2 months 12 days	1 year 2 months 12 days
Weighted-average discount rate - operating leases	10.10%	10.10%

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Subsequent Events - Oaktree Agreement $ in Millions	Oct. 13, 2022 USD ($)
Subsequent Event [Line Items]
Unpaid borrowings	$ 100
Funded Immediately
Subsequent Event [Line Items]
Unpaid borrowings	50
Up to Two Draws on or Prior to September 30, 2024
Subsequent Event [Line Items]
Unpaid borrowings	25
On or Prior to December 31, 2024
Subsequent Event [Line Items]
Unpaid borrowings	$ 25

Stock-Based Compensation - Schedule of RSU Activity (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Outstanding, December 31, 2021 \| shares	42,250
RSUs Granted \| shares	0
RSUs Vested \| shares	0
RSUs Forfeited \| shares	0
RSUs outstanding at September 30, 2022 \| shares	42,250
AVERAGE GRANT DATE FAIR VALUE, Outstanding, December 31, 2021 \| $ / shares	$ 3.25
AVERAGE GRANT DATE FAIR VALUE, Granted \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, Vested \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, Forfeited \| $ / shares	0
AVERAGE GRANT DATE FAIR VALUE, RSUs outstanding at September 30, 2022 \| $ / shares	$ 3.25