A Study to Evaluate Axatilimab Versus Best Available Therapy in Pediatric Participants With Chronic Graft-Versus-Host Disease After at Least 2 Prior Lines of Systemic Therapy (AGAVE-256)

To join this study, children and teenagers must be between 2 and 17 years old and have active moderate to severe chronic Graft-versus-Host Disease (cGVHD) that needs treatment. They must have tried at least two other medicines for cGVHD, including steroids and ruxolitinib, but their condition either hasn't improved or has come back. They can be taking steroids as part of their current treatment, as long as the dose has been steady for at least two weeks before starting the study.

Also, children must agree to receive one of several specific 'best available' treatments if they are put into that group of the study. They should have had a stem cell transplant from any donor, whether it was a family member or not, and from any source (bone marrow, blood, or cord blood).

However, some children cannot join. This includes those who have had more than one stem cell transplant or if their original illness (like cancer) has come back. If their kidneys or liver aren't working well, or if they have had severe swelling in their muscles, they also won't be able to take part. Girls who are pregnant or breastfeeding cannot join either.

If you join this study, your child will either receive the new medicine, Axatilimab, or one of the currently used 'best available' treatments for chronic GVHD. Which treatment your child receives will be decided by chance, like flipping a coin. This helps researchers compare the treatments fairly. Throughout the study, your child will have regular check-ups, blood tests, and other assessments to monitor their cGVHD and see how they are responding to the treatment. The study will also look for any side effects. The exact number of visits, tests, and total time your child will be involved will be explained in detail by the study team.