Gossamer Bio (GOSS) investor relations material

Regulatory and clinical progress

• Completed a Type B pre-NDA meeting with the FDA in June, with positive and collaborative feedback, and plan to file the NDA within weeks, expecting acceptance by late November.

• Addressed upcoming debt and refinanced, improving cash position; reacquired worldwide rights to seralutinib from Chiesi, now only owing low single-digit royalties.

• Presented new functional respiratory imaging data from the PROSERA phase III trial at ERS, showing promising effects on pulmonary vasculature.

• FDA indicated no filing issues, focusing review on clinical meaningfulness and risk-benefit, especially regarding liver safety.

• NDA will include comprehensive data: phase II TORREY, phase III PROSERA, imaging, echo, preclinical, and subgroup analyses.

Efficacy, safety, and subgroup insights

• Phase III top-line p-value was 0.032, above the traditional 0.05 threshold but below the EMA's stricter 0.025; FDA's updated guidance now supports 0.05 for rare diseases.

• Subgroup analyses revealed strong efficacy in CTD-associated PAH (37-meter improvement), less sick patients, and those diagnosed over five years, covering 90% of PROSERA and 93% of US PH populations.

• Geographic discrepancies noted: strong results in US and Western Europe, neutral in Latin America, attributed to different patient phenotypes and treatment paradigms.

• Safety and tolerability, especially in CTD patients, are highlighted as differentiators, with fewer liver elevations and better outcomes compared to competitors.

Market positioning and commercial strategy

• Seralutinib expected to be used after dual upfront therapy (PDE5/ERA), with potential for combination with sotatercept; pent-up demand anticipated at launch.

• Prostacyclins, including ralinepag, are expected to be relegated to later lines due to poor tolerability.

• Commercial team is prepared for launch, with sufficient resources and no need for a large sales force.