Macitentan in Adults with Sickle Cell Disease and Pulmonary Hypertension: A Proof-of-Concept Study

Abstract

Pulmonary hypertension (PH) in sickle cell disease (SCD) is associated with a mortality rate of 37%. There is an upregulation of adhesion molecules which leads to the expression of endothelin-1, a potent vasoconstrictor. A prospective, descriptive study was done to determine the safety and efficacy of macitentan in patients with SCD and PH. Continuous variables were reported as mean ± SEM or percentage where appropriate. We screened 13 patients and recruited five. All five patients were adults. Data were analyzed as appropriate by student t - test. Statistical significance was assumed at p < 0.05. Baseline pulmonary hemodynamics obtained by right heart catheterization and systemic hemodynamics were (± SEM): mean pulmonary artery pressure (MPAP) 32 ± 8 mmHg, right atrial pressure (RAP) 9 ± 4 mmHg, pulmonary vascular resistance (PVR) 257 dynes-sec/cm5 and CI 3·7 ± 0.39 l/m2. Of all parameters, only PVR and 6-min walk distance changed significantly. For the group, MPAP decreased by 15.6%, PVR by 22.5% and RAP by 25.5%. The 6-minute walk distance increased over sixteen weeks except in Patient 4 who had a 3% decrease. The mean walk distance increased in the total distance, from 464 ± 158 meters to 477 ± 190 meters (p .123). In four patients, the adverse events were mild to moderate and did not lead to study drug discontinuation. Significant improvement in pulmonary hemodynamics and exercise capacity in patients with SCD-related pulmonary arterial hypertension. We found that macitentan was safe and well tolerated.