Gossamer Bio, Inc.

Previous wording

We are a late-stage, clinical biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of PH, including PAH and PH-ILD. Our goal is to be an industry leader in, and to enhance the lives of patients living with PH. In May 2024, we entered into the Chiesi Collaboration Agreement focused on the development and commercialization of seralutinib. In December 2022, we announced positive topline results from the Phase 2 TORREY Study in PAH patients. In the fourth quarter of 2023, we initiated the registrational Phase 3 PROSERA Study in PAH. In June 2025, we announced the completion of enrollment for the ongoing, global registrational Phase 3 PROSERA Study evaluating seralutinib in Functional Class II and III PAH patients. We expect to report topline data from the PROSERA study in February 2026. In addition to PAH, we believe that seralutinib holds potential as a therapeutic for the treatment of PH-ILD. We expect to activate the first clinical sites for the global registrational Phase 3 SERANATA Study for the treatment of PH-ILD in the fourth quarter of 2025. We have assembled a deeply experienced and highly skilled group of industry veterans, scientists, clinicians and key opinion leaders from leading biotechnology and pharmaceutical companies, as well as leading academic centers from around the world. Our employees are a team of highly dedicated, passionate individuals who pride themselves on a culture of respect, humility, transparency, inclusion, dedication, collaboration and fun. Our ultimate goal is to enhance and extend the lives of patients.

Current wording

We are a late-stage, clinical biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of PH, including PAH and PH-ILD. Our goal is to be an industry leader in, and to enhance the lives of patients living with PH. In May 2024, we entered into the Chiesi Collaboration Agreement focused on the development and commercialization of seralutinib. In December 2022, we announced positive topline results from the Phase 2 TORREY Study in PAH patients. In the fourth quarter of 2023, we initiated the registrational Phase 3 PROSERA Study in PAH. In June 2025, we announced the completion of enrollment for the ongoing, global registrational Phase 3 PROSERA Study evaluating seralutinib in Functional Class II and III PAH patients. We expect to report topline data from the PROSERA study in February 2026. In addition to PAH, we believe that seralutinib holds potential as a therapeutic for the treatment of PH-ILD. In October 2025, we activated the first clinical site for the global registrational Phase 3 SERANATA Study for the treatment of PH-ILD. We have assembled a deeply experienced and highly skilled group of industry veterans, scientists, clinicians and key opinion leaders from leading biotechnology and pharmaceutical companies, as well as leading academic centers from around the world. Our employees are a team of highly dedicated, passionate individuals who pride themselves on a culture of respect, humility, transparency, inclusion, dedication, collaboration and fun. Our ultimate goal is to enhance and extend the lives of patients.

Previous wording

We were incorporated in October 2015 and commenced operations in 2017. To date, we have focused primarily on organizing and staffing our company, business planning, raising capital, identifying, acquiring and in-licensing our product candidates and conducting preclinical studies and clinical trials. We have funded our operations primarily through equity and debt financings and the collaboration agreement. As of June 30, 2025, we had $212.9 million in cash, cash equivalents and marketable securities.

Current wording

We were incorporated in October 2015 and commenced operations in 2017. To date, we have focused primarily on organizing and staffing our company, business planning, raising capital, identifying, acquiring and in-licensing our product candidates and conducting preclinical studies and clinical trials. We have funded our operations primarily through equity and debt financings and the collaboration agreement. As of September 30, 2025, we had $180.2 million in cash, cash equivalents and marketable securities.

Previous wording

We have incurred significant operating losses since our inception and expect to continue to incur significant operating losses for the foreseeable future. For the three months ended June 30, 2025 and 2024, our net loss was $38.3 million and net income was $49.2 million, respectively. For the six months ended June 30, 2025 and 2024, our net loss was $74.9 million and net income was $7.3 million, respectively. As of June 30, 2025, we had an accumulated deficit of $1,343.5 million. We expect to incur expenses and operating losses for the foreseeable future as we continue our development of and seek regulatory approvals for seralutinib, including the conduct of ongoing and planned clinical trials and other research and development activities; and as we hire additional personnel, protect our intellectual property and incur additional costs associated with being a public company. In addition, as seralutinib progresses through development and toward commercialization, we will need to make milestone payments to Pulmokine from whom we have in-licensed seralutinib. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending in particular on the timing of our clinical trials and preclinical studies and our expenditures on other research and development activities.

Current wording

We have incurred significant operating losses since our inception and expect to continue to incur significant operating losses for the foreseeable future. For the three months ended September 30, 2025 and 2024, our net loss was $48.2 million and $30.8 million, respectively. For the nine months ended September 30, 2025 and 2024, our net loss was $123.1 million and $23.5 million, respectively. As of September 30, 2025, we had an accumulated deficit of $1,391.7 million. We expect to incur expenses and operating losses for the foreseeable future as we continue our development of and seek regulatory approvals for seralutinib, including the conduct of ongoing and planned clinical trials and other research and development activities; and as we hire additional personnel, protect our intellectual property and incur additional costs associated with being a public company. In addition, as seralutinib progresses through development and toward commercialization, we will need to make milestone payments to Pulmokine from whom we have in-licensed seralutinib. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending in particular on the timing of our clinical trials and preclinical studies and our expenditures on other research and development activities.

Previous wording

Our management’s discussion and analysis of our financial condition and results of operations are based on our condensed consolidated financial statements, which have been prepared in accordance with GAAP. The preparation of these financial statements requires us to make judgments and estimates that affect the reported amounts of assets, liabilities, revenue, expenses and the disclosure of contingent assets and liabilities in our condensed consolidated financial statements. We base our estimates on historical experience, known trends and events, and various other factors that are believed to be reasonable under the circumstances. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, we evaluate our judgments and estimates in light of changes in circumstances, facts and experience. During the six months ended June 30, 2025, there have been no significant changes in our critical accounting policies and estimates as discussed in Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Critical Accounting Policies and Estimates” in our Annual Report on Form 10-K filed with the SEC on March 13, 2025.

Current wording

Our management’s discussion and analysis of our financial condition and results of operations are based on our condensed consolidated financial statements, which have been prepared in accordance with GAAP. The preparation of these financial statements requires us to make judgments and estimates that affect the reported amounts of assets, liabilities, revenue, expenses and the disclosure of contingent assets and liabilities in our condensed consolidated financial statements. We base our estimates on historical experience, known trends and events, and various other factors that are believed to be reasonable under the circumstances. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, we evaluate our judgments and estimates in light of changes in circumstances, facts and experience. During the nine months ended September 30, 2025, there have been no significant changes in our critical accounting policies and estimates as discussed in Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Critical Accounting Policies and Estimates” in our Annual Report on Form 10-K filed with the SEC on March 13, 2025.

Previous wording

Results of Operations – Comparison of the Three and Six Months Ended June 30, 2025 and 2024

Current wording

Results of Operations – Comparison of the Three and Nine Months Ended September 30, 2025 and 2024

Previous wording

The following table sets forth our selected statements of operations data for the six months ended June 30, 2025 and 2024:

Current wording

The following table sets forth our selected statements of operations data for the nine months ended September 30, 2025 and 2024:

Previous wording

For the three months ended June 30, 2025 and 2024, our revenue was $11.5 million and $95.8 million, respectively. For the six months ended June 30, 2025 and 2024, our revenue was $21.4 million and $95.8 million, respectively. Our revenue is generated from our ongoing collaboration with Chiesi and consists of a one-time development cost reimbursement payment for the licenses and ongoing cost-sharing payments for performance of research and development and pre-commercial services.

Current wording

For the three months ended September 30, 2025 and 2024, our revenue was $13.3 million and $9.5 million, respectively. For the nine months ended September 30, 2025 and 2024, our revenue was $34.7 million and $105.3 million, respectively. Our revenue is generated from our ongoing collaboration with Chiesi and consists of a one-time development cost reimbursement payment for the licenses and ongoing cost-sharing payments for performance of research and development and pre-commercial services.

Previous wording

Research and development expenses were $41.6 million for the three months ended June 30, 2025, compared to $35.1 million for the three months ended June 30, 2024, for an increase of $6.5 million, which was primarily attributable to an increase of $9.0 million of costs associated with preclinical studies and clinical trials for seralutinib, offset by a decrease of $2.5 million of costs associated with preclinical studies and clinical trials for terminated programs.

Current wording

Research and development expenses were $45.5 million for the three months ended September 30, 2025, compared to $34.9 million for the three months ended September 30, 2024, for an increase of $10.6 million, which was primarily attributable to an increase of $12.8 million of costs associated with preclinical studies and clinical trials for seralutinib, offset by a decrease of $2.1 million of costs associated with preclinical studies and clinical trials for terminated programs.

Previous wording

Research and development expenses were $79.6 million for the six months ended June 30, 2025, compared to $67.5 million for the six months ended June 30, 2024, for an increase of $12.1 million, which was primarily attributable to an increase of $17.2 million of costs associated with preclinical studies and clinical trials for seralutinib, offset by a decrease of $5.1 million of costs associated with preclinical studies and clinical trials for terminated programs.

Current wording

Research and development expenses were $125.2 million for the nine months ended September 30, 2025, compared to $102.4 million for the nine months ended September 30, 2024, for an increase of $22.8 million, which was primarily attributable to an increase of $30.1 million of costs associated with preclinical studies and clinical trials for seralutinib, offset by a decrease of $7.3 million of costs associated with preclinical studies and clinical trials for terminated programs.

Previous wording

The following table shows our research and development expenses by program for the three and six months ended June 30, 2025 and 2024:

Current wording

The following table shows our research and development expenses by program for the three and nine months ended September 30, 2025 and 2024:

Previous wording

General and administrative expenses were $17.3 million for the six months ended June 30, 2025, compared to $18.2 million for the six months ended June 30, 2024, for a decrease of $0.9 million, which was primarily attributable to a $2.8 million decrease in stock-based compensation expense, offset by an increase of $2.0 million in commercial expenses.

Current wording

General and administrative expenses were $9.4 million for the three months ended September 30, 2025, compared to $8.5 million for the three months ended September 30, 2024, for an increase of $0.9 million, which was primarily attributable to a $1.2 million increase in commercial expenses, $0.5 million increase in legal expenses and $0.3 million increase in personnel expenses, offset by a $1.2 million decrease in stock-based compensation expense.

Previous wording

There was no change in general and administrative expenses for the three months ended June 30, 2025 and 2024. General and administrative expenses in both periods were $8.7 million.

Current wording

There was no change in general and administrative expenses for the nine months ended September 30, 2025 and 2024. General and administrative expenses in both periods were $26.7 million.

Previous wording

Other income, net was $0.5 million for the three months ended June 30, 2025, compared to $1.6 million for the three months ended June 30, 2024, for a decrease of $1.1 million, which was primarily attributable to a $1.2 million decrease in interest income, offset by a $0.2 million decrease in interest expense.

Current wording

Other income, net was $1.6 million for the nine months ended September 30, 2025, compared to $3.6 million for the nine months ended September 30, 2024, for a decrease of $2.0 million, which was primarily attributable to a $4.1 million decrease in investment accretion, $1.0 million decrease in interest income, offset by a $0.5 million decrease in interest expense and $2.2 million increase in other income related to the refund of the employee retention credit under the CARES Act of $1.4 million and R&D tax credit of $1.1 million.

Previous wording

There was no provision for income taxes for the three and six months ended June 30, 2025. Provision for income taxes was $4.4 million for the three and six months ended June 30, 2024.

Current wording

There was no provision (benefit) for income taxes for the three and nine months ended September 30, 2025. For the three and nine months ended September 30, 2024, the (benefit) provision for income taxes was $1.1 million and $3.3 million, respectively. The tax benefit recognized in the three months ended September 30, 2024 is primarily attributable to a reduction of expense in the period based on our forecasted spend used in calculating our quarterly tax provision. The tax expense recognized in the nine months ended September 30, 2024 is primarily attributable to the treatment of the Chiesi income and a partial release of the valuation allowance.

Previous wording

We have incurred substantial operating losses since our inception and expect to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of June 30, 2025, we had an accumulated deficit of $1,343.5 million.

Current wording

We have incurred substantial operating losses since our inception and expect to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of September 30, 2025, we had an accumulated deficit of $1,391.7 million.

Previous wording

From our inception through June 30, 2025, our operations have been financed primarily by proceeds of $1,393.2 million from the sale of Series A and Series B convertible preferred stock, proceeds from our IPO, proceeds from the 2027 Notes, proceeds from issuance of common stock in May 2020 and July 2022, proceeds from issuance of common stock and accompanying warrants in July 2023 and the Chiesi Collaboration Agreement. In addition, we have received $19.8 million as of June 30, 2025 through reimbursement related to the Chiesi Collaboration Agreement. As of June 30, 2025 we had cash, cash equivalents and marketable securities of $212.9 million. Cash in excess of immediate requirements is invested in accordance with our investment policy, primarily with a view to capital preservation and liquidity.

Current wording

From our inception through September 30, 2025, our operations have been financed primarily by proceeds of $1,394.2 million from the sale of Series A and Series B convertible preferred stock, proceeds from our IPO, proceeds from the 2027 Notes, proceeds from issuance of common stock in May 2020 and July 2022, proceeds from issuance of common stock and accompanying warrants in July 2023 and the Chiesi Collaboration Agreement. In addition, we have received $27.3 million as of September 30, 2025 through reimbursement related to the Chiesi Collaboration Agreement. As of September 30, 2025 we had cash, cash equivalents and marketable securities of $180.2 million. Cash in excess of immediate requirements is invested in accordance with our investment policy, primarily with a view to capital preservation and liquidity.

Previous wording

On May 3, 2024, we entered into the Chiesi Collaboration Agreement. In consideration and as reimbursement for our development costs, Chiesi paid us an up-front, nonrefundable payment of $160.0 million. In addition, we and Chiesi share equally in the costs of ongoing global seralutinib clinical development, with the exception of the PROSERA Phase 3 study, and the costs of commercialization in the U.S. Territory. For the six months ended on June 30, 2025, we received cost-sharing payments from Chiesi in the amount of $11.9 million.

Current wording

On May 3, 2024, we entered into the Chiesi Collaboration Agreement. In consideration and as reimbursement for our development costs, Chiesi paid us an up-front, nonrefundable payment of $160.0 million. In addition, we and Chiesi share equally in the costs of ongoing global seralutinib clinical development, with the exception of the PROSERA Phase 3 study, and the costs of commercialization in the U.S. Territory. For the nine months ended on September 30, 2025, we received cost-sharing payments from Chiesi in the amount of $19.5 million.

Previous wording

The following table shows a summary of our cash flows for each of the six months ended June 30, 2025 and 2024, respectively:

Current wording

The following table shows a summary of our cash flows for each of the nine months ended September 30, 2025 and 2024, respectively:

Previous wording

During the six months ended June 30, 2025, operating activities used approximately $86.8 million of cash, primarily resulting from a net loss of $74.9 million, changes in accounts payable of $6.8 million, changes in prepaid expenses and other current assets of $5.4 million and changes in amortization of premium on investments of $4.6 million, reduced by changes in stock-based compensation expense of $5.0 million.

Current wording

During the nine months ended September 30, 2025, operating activities used approximately $123.0 million of cash, primarily resulting from a net loss of $123.1 million, changes in accounts payable of $7.6 million and changes in amortization of premium on investments of $6.2 million, reduced by changes in stock-based compensation expense of $7.7 million and changes in in process research and development expense of $7.5 million.

Previous wording

During the six months ended June 30, 2024, operating activities provided approximately $64.0 million of cash, primarily resulting from a net income of $7.3 million and changes in contract liabilities of $66.7 million, reduced by changes in accrued expenses of $6.3 million and changes in amortization of premium on marketable securities, net of accretion of $6.0 million.

Current wording

During the nine months ended September 30, 2024, operating activities provided approximately $32.0 million of cash, primarily resulting from changes in contract liabilities of $64.1 million and changes in stock-based compensation expense of $15.7 million, reduced by the net loss of $23.5 million, changes in amortization of premium on investments, net of accretion of discount, of $9.7 million, changes in accrued expenses of $9.8 million and changes in accounts payable of $4.7 million.

Previous wording

During the six months ended June 30, 2025, investing activities provided approximately $66.2 million of cash, primarily resulting from the maturities of marketable securities of $242.8 million, offset by the purchases of marketable securities of $176.5 million.

Current wording

During the nine months ended September 30, 2025, investing activities provided approximately $83.2 million of cash, primarily resulting from the maturities of marketable securities of $289.4 million, offset by the purchases of marketable securities of $206.1 million.

Previous wording

During the six months ended June 30, 2024, investing activities provided approximately $2.6 million of cash, primarily resulting from the maturities of marketable securities of $282.3 million, offset by the purchases of marketable securities of $279.7 million.

Current wording

During the nine months ended September 30, 2024, investing activities used approximately $24.2 million of cash, primarily resulting from the purchases of marketable securities of $411.1 million, offset by the maturities of marketable securities of $386.9 million.

Previous wording

During the six months ended June 30, 2025, financing activities provided $0.6 million of cash, primarily resulting from the proceeds from issuance of common stock pursuant to the ESPP of $0.4 million and the proceeds from the exercise of stock options of $0.2 million.

Current wording

During the nine months ended September 30, 2025, financing activities provided $2.5 million of cash, primarily resulting from the proceeds from the exercise of warrants of $0.9 million, the proceeds from issuance of common stock pursuant to the ESPP of $0.8 million and the proceeds from the exercise of stock options of $0.7 million.

Previous wording

During the six months ended June 30, 2024, financing activities used $11.8 million of cash, primarily resulting from the principal repayments of long-term debt of $12.6 million, reduced by the proceeds from the grant of an equity option pursuant to the Chiesi Collaboration Agreement of $0.5 million and the proceeds from issuance of common stock pursuant to the ESPP of $0.3 million.

Current wording

During the nine months ended September 30, 2024, financing activities used $11.5 million of cash, primarily resulting from the principal repayments of long-term debt of $12.6 million, reduced by the proceeds from issuance of common stock pursuant to the ESPP of $0.6 million and the proceeds from the grant of an equity option pursuant to the Chiesi Collaboration Agreement of $0.5 million.