Research and development expenses
R&D expenses decreased $0.9 million, or 13%, to $5.8 million for the six months ended June 30, 2024, compared to the six months ended June 30, 2023. This change was driven by a $0.5 million decrease in consulting expenses, a $0.1 million decrease in non-cash stock-based compensation expense, and a $0.1 million decrease in travel expenses.
Selling, general and administrative expenses
SG&A expenses increased $17.6 million, or 55%, to $49.4 million for the six months ended June 30, 2024, compared to the six months ended June 30, 2023. This change was primarily driven by a $10.6 million increase in non-cash stock-based compensation expense, a $4.6 million increase in compensation expenses, mainly as a result of increased headcount, a $0.6 million increase in advertising expenses, a $0.5 million increase in travel 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 $1.2 million for the six months ended June 30, 2024, compared to the six months ended June 30, 2023. This increase was driven by the interest expense on borrowings under the Loan Agreement entered into on October 31, 2022.
Other income, net
Other income, net increased $0.3 million for the six months ended June 30, 2024, compared to the six months ended June 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 six months ended June 30, 2024 and June 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 June 30, 2024 and December 31, 2023, we had cash and cash equivalents of $70.4 million and $90.6 million, respectively. For the three months ended June 30, 2024 and 2023, our net losses were $14.0 million and $11.7 million, respectively. For the six months ended June 30, 2024 and 2023, our net losses were $36.2 million and $23.0 million, respectively. Our net cash used in operating activities for the six months ended June 30, 2024 and 2023 was $20.7 million and $23.1 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. We had $30.0 million in outstanding Term Loans under the Loan Agreement as of June 30, 2024. The Loan Agreement provides for an additional tranche of up to $20.0 million, based on the timing and other conditions set forth in the Loan Agreement.