Phase II clinical trial evaluating Abatacept in patients with steroid-refractory chronic graft versus host disease.

Steroid-refractory chronic graft versus host disease (cGVHD) remains a significant cause of morbidity and mortality following allogeneic transplantation. Abatacept is a selective co-stimulation modulator, used for the treatment of rheumatologic disease, and was recently the first drug to be approved by the FDA for the prophylaxis of acute graft versus host disease. We conducted a Phase II study to evaluate the efficacy of Abatacept in steroid-refractory cGVHD (clinicaltrials.gov #NCT01954979). The overall response rate was 58%, with all responders achieving a partial response. Abatacept was well-tolerated with few serious infectious complications. Immune correlative studies showed a decrease in IL-1-alpha, IL-21, and TNF-alpha as well as decreased PD-1 expression by CD4+ T cells in all patients after treatment with Abatacept, demonstrating the effect of this drug on the immune microenvironment. The results demonstrate that Abatacept is a promising therapeutic strategy for the treatment of cGVHD.