Abstract
This trial will see if extended abatacept administration (combined with a standard regimen of tacrolimus and mycophenolate mofetil) will prevent acute and chronic graft-versus-host disease (GVHD) in children and adolescents receiving unrelated donor (URD) hematopoietic stem cell transplantation (HSCT), without compromising their engraftment or reconstitution of protective immunity to infection. The study will enroll 30 pediatric patients with serious non-malignant hematologic diseases (NMHD) undergoing URD HSCT. The trial will include patients with 7/8 donors and those with 8/8 (matched) donors. All participants will receive 8 doses of abatacept. Recruitment is expected to last for about 2 years and participants will be followed for up to 3 years.