Clinical efficacy and safety of switch from bosentan to macitentan in children and young adults with pulmonary arterial hypertension: extended study results

Background:Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term study.Aim:We have recently reported that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension in a 24-week prospective study and well tolerated without adverse events. We now aimed to evaluate clinical efficacy, safety of switch in a larger patient population, in a 24-month prospective study.Methods:This is a single-institution, 24-month prospective study. Patients ≥12 years with idiopathic/heritable, pulmonary arterial hypertension, or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan treatment were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors/inhaled prostanoids was allowed. Outcome measures included change from baseline to 24 months, in the 6-minute walk distance, functional class, oxygen saturation at rest/after walk distance test, and natriuretic peptide levels. Safety end points included adverse events, laboratory abnormalities.Results:Twenty-seven patients (19 adults/8 children, mean age: 21.1 ± 6.3 years (12–36), weight: 53.1 ± 15.7 kgs (26–87)) were included. Mean duration of macitentan treatment: 22.3 ± 3.9 months (9–24). Six-minute walk distance significantly improved from baseline (mean: 458 ± 79 m (300–620)) at 6 months (mean: 501 ± 73 m (325–616) + 43 m) (p < 0.05), at 12 months (mean: 514 ± 82 m (330–626) + 56 m) (p < 0.05), and at 24 months (mean: 532 ± 85 m (330–682) + 74 m) (p < 0.05). We observed a significant improvement during the first 6 months but no incremental improvement after 6 months (p > 0.05). Macitentan did not significantly change functional class, oxygen saturation, and natriuretic levels (p > 0.05). None of the patients had anaemia, hepatotoxicity, and peripheral edema.Conclusions:Our study is the first study which showed that switch from bosentan to macitentan improved exercise capacity in children and young adults with pulmonary arterial hypertension significantly in the first 6 months and compared to baseline in 24 months and well tolerated without adverse events.