Safety and Efficacy of Selexipag for Pediatric Pulmonary Arterial Hypertension in Japanese Patients - An Open-Label Phase 2 Study

Background: Selexipag, an oral prostacyclin (PGI₂) receptor agonist, is approved for adult patients with pulmonary arterial hypertension (PAH). This study evaluated the efficacy and safety of selexipag for Japanese pediatric patients with PAH.

Methods and results: The study enrolled 6 patients who received selexipag twice daily at an individualized dose based on body weight; maintenance doses were determined for each patient by 12 weeks after starting administration. Efficacy, including pulmonary hemodynamics, was evaluated after 16 weeks, and efficacy and safety were further evaluated 52 weeks after treatment was initiated in the last enrolled patient. The mean (±SD) change in the pulmonary vascular resistance index from baseline to Week 16 (the primary endpoint of the study) was -5.55±6.88 Wood units·m²; improvements were also seen in other pulmonary hemodynamic parameters. The 6-min walk distance increased and N-terminal pro-B-type natriuretic peptide decreased up to Week 64, but the between-subject variability was large. The World Health Organization functional class was improved in 1 of 6 patients at Week 16 and in 2 of 4 patients at Week 64. No patient worsened. The major side effects of selexipag were those characteristic of PGI₂, and the safety profile of selexipag was similar to that in adult patients.

Conclusions: The efficacy and safety of selexipag in Japanese pediatric patients with PAH were demonstrated.