Gossamer Bio (GOSS) investor relations material

Company overview and clinical development

• Founded in 2018, initially focused on seralutinib, a potent, selective inhaled TKI for PAH, aiming for improved safety and efficacy over prior therapies.

• Seralutinib was designed to address side effects seen with imatinib, offering a more benign profile and inhaled delivery.

• The Prosera phase 3 trial is a multinational study with top-line data expected in February next year, targeting a 20-25 meter increase in six-minute walk distance.

• Regulatory filings and potential launch are anticipated for late Q2 2027, aiming for significant market leadership.

Clinical trial design and patient population

• Prosera enrolled sicker patients than the earlier Tori study, with 70% functional class three and lower baseline walk distances, enhancing the likelihood of demonstrating efficacy.

• Only 17% of Prosera patients are from the U.S., with a focus on regions that showed strong efficacy in precedent studies.

• Few patients were enrolled on background sotatercept due to adverse events and stability requirements, highlighting seralutinib’s potential safety advantage.

• Top-line data will include primary and some key secondary endpoints, with imaging data on lung revascularization expected later in the year.

Commercial strategy and market landscape

• Seralutinib is positioned as a third-line agent after standard of care, with no new safety or tolerability signals observed in phase 3 blinded data.

• Payer management is minimal in this rare disease space, and major therapies will be generic by 2027, reducing combination therapy costs by 80-90%.

• Outside the U.S., seralutinib’s safety profile is expected to ease reimbursement negotiations compared to competitors with higher adverse event burdens.

• Commercial buildout is underway, targeting 60 sales reps at launch, focusing initially on major centers and then expanding to the broader community.

• Pricing will be benchmarked to Tyvaso and Winrevair, with specifics determined after phase 3 data.