A Study of Selexipag as Add-On Treatment to Standard of Care in Children With Pulmonary Arterial Hypertension

This study is looking for children and teenagers between 2 and 17 years old who weigh at least 9 kilograms (about 20 pounds) and have a confirmed diagnosis of pulmonary arterial hypertension (PAH).

To be considered, your child's PAH must fall into certain types, including those that are inherited, those linked to some congenital heart conditions, or PAH that developed after certain heart surgeries or due to specific infections like HIV. They should also be in WHO functional class II or III, which describes how much their symptoms affect their daily life. Importantly, they must already be on at least one standard PAH treatment, such as an endothelin receptor antagonist or a phosphodiesterase type-5 inhibitor, and have been on a stable dose for at least three months.

Children generally cannot take part if their PAH is due to certain other serious conditions like liver problems or blood vessel blockages, or if they have a condition called Eisenmenger syndrome. Those who have previously taken selexipag, have other serious illnesses that shorten life expectancy, are pregnant or breastfeeding, or are allergic to selexipag or its ingredients will also not be able to join. It's crucial to discuss all your child's medical history with the study doctors.

If your child participates, they will first go through a 'screening period' for up to six weeks. This is to check if they are suitable for the study. If they are, they will then enter the main 'double-blind treatment period'. In this part, neither you nor the doctors will know if your child is receiving selexipag or a dummy medicine called a placebo, in addition to their current PAH treatments. The dose of the study medicine will start low and be gradually increased (up-titration) to find the right level, followed by a 'maintenance' period where they take a stable dose.

After the double-blind part, there will be an 'open-label extension period' for three years. In this phase, all children will receive selexipag. Throughout the study, there will be regular check-ups to monitor your child's health, how the medicine is affecting them, and how well it is working. The study team will also collect blood samples. Following the end of all treatment, there will be a final safety check-up about a month later. The entire study, from start to finish, is expected to last about 8 years.