Winrevair's Label Grows Into Early Disease: FDA Adds HYPERION Data — 76% Fewer Clinical Worsening Events in Newly Diagnosed PAH
September 22, 2026. Merck announced that the FDA approved a label update for WINREVAIR (sotatercept-csrk), the first activin signaling inhibitor for pulmonary arterial hypertension, adding efficacy and safety data from the Phase 3 HYPERION trial in adults newly diagnosed with PAH (WHO FC II–III, diagnosed within 12 months of screening) (Merck press release, Sept 22, 2026).
The number that matters: In HYPERION (N=320), "adding WINREVAIR to background therapy reduced the risk of clinical worsening events by 76% in adults with PAH WHO functional class II or III compared to placebo (hazard ratio [HR] 0.24; [95% confidence interval [CI], 0.14 to 0.41]; p<0.0001)" (Merck). Per HCPLive, a first clinical-worsening event — death, PAH hospitalization, septostomy, or transplant — occurred in 10.6% of sotatercept patients vs 36.9% on placebo (HCPLive). HYPERION was stopped early after the positive ZENITH interim analysis.
Context:
- This is the third Phase 3 trial of sotatercept written into the label, after STELLAR and ZENITH — and it extends the evidence base to the earliest stage of disease, supporting initiation within the first year after diagnosis rather than reserving the drug for refractory cases.
- The update follows the new ERS pulmonary hypertension guidelines published this month — the first formal guidelines to include Winrevair (AJMC).
- The label also picked up new safety language: a contraindication for serious hypersensitivity (anaphylaxis, angioedema), plus hemoglobin/platelet monitoring guidance reflecting erythrocytosis and thrombocytopenia risks; discontinuations in HYPERION were uncommon (3%) and no sotatercept-treated patient's platelets fell below 50,000/mm³ (HCPLive).
What it means: Sotatercept's trajectory keeps moving one direction — from add-on therapy for advanced PAH toward early, near-universal use at diagnosis, with a 76% risk reduction in newly diagnosed patients now in the label and guideline recognition arriving in the same month. Watch for the updated ERS guidance and ongoing ZENITH follow-up to consolidate that positioning.