Background: PAH is a progressive disease with high morbidity and mortality

Aims: Using post-hoc analyses of the Phase 3 STELLAR study (a multicenter, double-blind study testing safety & efficacy of sotatercept, an activin signaling inhibitor) on risk stratification and quality of life, we developed a decision-analytic model to compare long term survival in patients treated with sotatercept vs placebo on top of background therapies

Methods: Individual patient data from STELLAR were stratified as per the recent 2022 ESC/ERS risk classification based on 6-minute walk distance, NT-proBNP, and functional class. Distribution of risk strata was assessed at baseline, weeks 3, 12, and 24. A Markov cohort model was developed to compare survival over a 30year horizon for patients on sotatercept vs background therapy alone. Risks of PAH hospitalization and all-cause mortality were based on STELLAR and the European registry COMPERA. EQ5D in STELLAR informed quality of life. Outcomes included patient survival, change in risk stratification over time, and rates of PAH-related organ transplant and hospitalizations due to disease worsening

Results: Primary results of STELLAR are pending presentation on March 6, 2023. Top line results are available at www.merck.com. Due to embargo requirements, the results of the current analysis will be submitted to ERS after March 6

Conclusion: A significantly greater proportion of patients achieved low risk score as per 2022 ESC/ERS guidelines with sotatercept vs. placebo. The clinical model is the first study to project the long-term efficacy of sotatercept on morbidity and mortality in patients with PAH