Research and development expenses
R&D expenses decreased $1.1 million, or 11%, to $8.3 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023. This change was driven by a $0.7 million decrease in consulting expenses, a $0.1 million decrease in travel expenses, a $0.1 million decrease in non-cash stock-based compensation expense, and a $0.1 million decrease in compensation expenses.
Selling, general and administrative expenses
SG&A expenses increased $23.6 million, or 50%, to $71.1 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023. This change was primarily driven by an $11.7 million increase in non-cash stock-based compensation expense, an $8.2 million increase in compensation expenses, mainly as a result of increased headcount, a $1.2 million increase in travel expenses, a $0.9 million increase in advertising expenses, and a $0.5 million increase in consulting expenses. Approximately $8.4 million of the increase in non-cash stock-based compensation expense is related to the modification of stock options held by the former CEO in connection with his retirement in the first quarter of 2024 described in Note 7 to our condensed consolidated financial statements included elsewhere in this Quarterly Report on Form 10-Q.
Interest expense
Interest expense increased $1.7 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023. This increase was driven by the interest expense on higher levels of borrowings under the Loan Agreement entered into on October 31, 2022.
Other income, net
Other income, net increased $0.2 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023. This increase was primarily driven by greater interest income on our interest-bearing accounts.
Provision for income taxes
Provision for income taxes was nominal for each of the nine months ended September 30, 2024 and September 30, 2023.
Liquidity, capital resources and plan of operations
We have incurred significant operating losses and negative cash flows from operations since our inception, and we anticipate that we will incur significant losses for at least the next several years. As of September 30, 2024 and December 31, 2023, we had cash and cash equivalents of $100.2 million and $90.6 million, respectively. For the three months ended September 30, 2024 and 2023, our net losses were $13.1 million and $9.0 million, respectively. For the nine months ended September 30, 2024 and 2023, our net losses were $49.3 million and $32.0 million, respectively. Our net cash used in operating activities for the nine months ended September 30, 2024 and 2023 was $31.1 million and $31.2 million, respectively.
On October 31, 2022, we entered into the Loan Agreement under which we may borrow, subject to our achievement of certain milestones, up to a total of $50.0 million in a series of Term Loans described in Note 4 to our condensed consolidated financial statements included elsewhere in this Quarterly Report on Form 10-Q, and we borrowed $7.5 million of such total on that date to fund our commercial and investment efforts. On March 10, 2023, we borrowed the $7.5 million remaining under the first tranche of the Loan Agreement. On December 15, 2023, we borrowed $15.0 million under the second tranche of the Loan Agreement. On September 30, 2024, we borrowed the remaining $20.0 million under the third and final tranche of the Loan Agreement. We had $50.0 million in outstanding Term Loans under the Loan Agreement as of September 30, 2024.