Efficacy and Safety of Sotatercept Across Ranges of Cardiac Index in Patients with Pulmonary Arterial Hypertension: A Pooled Analysis of PULSAR and STELLAR

Background: This analysis compared effects of the activin signaling inhibitor, sotatercept, across pulmonary arterial hypertension (PAH) subgroups stratified by baseline cardiac index (CI).

Methods: Pooled data from PULSAR (N=106; NCT03496207) and STELLAR (N=323; NCT04576988) were analyzed using two different CI thresholds, < and ≥ 2.0 L/min/m² or 2.5 L/min/m². Median differences in change from baseline at week 24 were evaluated using Hodges-Lehmann (HL) estimator and mean differences by least squares (LS), with 95% confidence intervals and p-values; p=0.05 was significant. Categorial endpoints and time-to-clinical worsening were analyzed by Cochran-Mantel-Haenszel and Cox model (hazard ratio (HR), respectively, without multiplicity adjustment.

Results: Of 429 participants, 51 and 378 had CI <2.0 L/min/m² and ≥ 2.0 L/min/m², respectively, whereas 179 and 250 had CI <2.5 L/min/m² and ≥ 2.5 L/min/m², respectively. Across all CI subgroups, sotatercept vs placebo significantly improved median 6-minute walk distance (range: 33.9 to 63.7 m: p<0.001), pulmonary vascular resistance (range: -202.8 to -395.4 dyn•s•cm^-5; p≤0.002), and N-terminal pro-B-type natriuretic peptide (range: -317.3 to -1041.2 pg/mL; p<0.001). LS means showed reductions in pulmonary and right atrial pressures, decreased right ventricular size and enhanced tricuspid annular plane systolic excursion/ systolic pulmonary artery pressure in all subgroups. Sotatercept significantly delayed time to first occurrence of death or a worsening event in the subset of participants with CI ≥2.5 (HR 0.12; p<0.001), ≥2.0 (HR 0.13; p<0.001), and <2.5 (HR 0.21; p<0.001) L/min/m². Improvements in World Health Organization functional class (all p<0.050) and European Society of Cardiology/European Respiratory Society risk score (all p<0.001) were seen within each subgroup.

Conclusions: Efficacy and safety were consistent across baseline CI subgroups, supporting use of sotatercept in PAH patients irrespective of baseline cardiac hemodynamics.