Gossamer Bio (GOSS) Investor update summary

Regulatory and clinical development update

• FDA confirmed statistical significance and treatment effect in PROSERA are review issues, not filing barriers, supporting a planned NDA submission for seralutinib in PAH in September 2026.

• NDA will be based on PROSERA as a pivotal study, with TORREY providing independent confirmatory evidence and additional supportive analyses.

• If accepted, FDA approval decision for seralutinib could occur in Q3 2027.

• Label negotiations are expected to seek a broad indication, with subgroups and sensitivity analyses supporting efficacy across populations.

• No safety issues or REMS were discussed at the pre-NDA meeting; these will be addressed during NDA review.

Strategic and commercial updates

• Worldwide development and commercial rights to seralutinib were reacquired, consolidating global control and economics, with Chiesi retaining only capped royalties and milestone payments.

• Chiesi will pay $5 million to Gossamer post-signing; prior profit-sharing replaced by finite, success-based obligations.

• Chiesi's shift in focus to ultra-rare diseases and internal reorganization influenced the rights reacquisition.

• Plans are underway to resume launch readiness activities, targeting a commercial launch in August/September 2027.

• Ex-U.S. regulatory filings, especially in Europe, are planned, leveraging internal expertise and market assessments.

Financial and capital structure update

• Convertible note exchange reduced debt by $115.9 million, with new 7.5% convertible secured notes due 2030 issued.

• Stockholders approved all proposals, including authorization for a reverse stock split to support Nasdaq compliance.

• Cash, cash equivalents, and marketable securities totaled approximately $57 million as of June 30, 2026.