Macitentan and Tadalafil Combination Therapy in Incident and Prevalent Pulmonary Arterial Hypertension: Real-World Evidence from the OPUS/OrPHeUS Studies

Introduction Historically, patients recently (<= 6 months) diagnosed with pulmonary arterial hypertension (PAH; incident) have had poorer survival than those with a longer (> 6 months) time from PAH diagnosis (prevalent). Despite guideline recommendations for initial combination therapy for most patients with PAH, many are initiated and maintained on monotherapy. Real-world evidence to evaluate the benefit of early combination treatment in newly-diagnosed patients is lacking. Methods Patients with PAH initiating combination therapy with the endothelin receptor antagonist macitentan and the phosphodiesterase-5 inhibitor tadalafil (M+T) were identified from the combined dataset of the US, multicenter OPUS (prospective, observational drug registry; NCT02126943) and OrPHeUS (retrospective, medical chart review; NCT03197688) studies (2013-2020). Descriptive analyses were performed for the incident and prevalent cohorts, as well as the subcohort of incident patients who received M+T as first-line combination therapy (incident initial combination). Results In OPUS/OrPHeUS, 1336 patients with PAH received M+T during the observation period. For the incident [n = 453 (33.9%)], incident initial combination [n = 272 (20.4%)], and prevalent [n = 837 (62.6%)] cohorts: median (Q1, Q3) M+T exposure was 14.2 (4.2, 27.5), 12.2 (3.2, 25.5), and 14.7 (4.5, 28.0) months. 12-month Kaplan-Meier estimates (95% confidence limits) for survival were 91.2% (87.7, 93.7), 88.5% (83.2, 92.2), and 92.9% (90.6, 94.6), for patients free from hospitalization were 59.4% (54.1, 64.4), 56.3% (49.1, 62.9), and 62.3% (58.5, 65.9), and for patients persisting on combination therapy were 68.6% (63.9, 72.8), 65.0% (58.8, 70.6) and 66.9% (63.5, 70.0). Adverse events (OPUS only) were reported in 77.8%, 80.2%, and 80.3% of patients, respectively, with no unexpected adverse events observed. Conclusions Despite a historically worse prognosis, incident patients receiving M+T, including as initial combination therapy, had similar survival and hospitalization as prevalent patients. Safety profiles were similar across cohorts. Together, these data support the use of early combination therapy with macitentan and tadalafil.