Gossamer Bio (GOSS) Emerging Growth Conference 79 summary

Market opportunity and disease focus

• Seralutinib targets pulmonary arterial hypertension (PAH) and PH associated with interstitial lung disease, representing a $6–$10 billion market opportunity.

• PAH affects about 50,000 people in the US, with similar prevalence in the EU, Japan, and Australia.

• Median mortality for PAH is about five years, and even lower for PH-ILD, highlighting the severity and unmet need.

• Seralutinib is designed as an inhaled therapy, delivering the drug directly to the lungs to maximize potency and minimize systemic side effects.

• Patent protection extends until 2039, with orphan disease designation in the US, EU, and Japan.

Clinical development and data

• Phase II TORREY study showed a 14% reduction in pulmonary vascular resistance (PVR) at 24 weeks, with greater efficacy in sicker patients.

• At 72 weeks, patients on seralutinib achieved a 25% mean reduction in PVR, matching results seen with Merck's sotatercept but with a better safety profile.

• Secondary endpoints, including biomarkers and hemodynamics, were statistically significant, and efficacy improved over time.

• Side effects are mainly mild, such as cough and minor headache, with no serious safety issues reported.

• The ongoing multinational phase III PROSERA study is enrolling sicker patients to better demonstrate efficacy, with enrollment expected to complete in Q2 2024 and top-line data in Q4 2024.

Competitive landscape and positioning

• Existing therapies (ERAs, PDE5s, prostacyclins) primarily treat symptoms and have significant side effects or are used in late-stage disease.

• Recently approved sotatercept (Winrevair) offers a new mechanism but carries significant bleeding risks and other serious side effects.

• Seralutinib is positioned as a safer, more targeted therapy with sustained efficacy, potentially becoming the preferred option after generics.

• The PH-ILD market is largely untapped outside the US, presenting a major growth opportunity.