CTLA4 and graft versus host disease: To describe transplantation outcomes with regard to GvHD and the effects of various GvHD prophylaxis strategies, Oran and colleagues conducted a clinical trial of patients with AML and MDS patients treated with either PD-1 (nivolumab) and/or CTLA-4 (ipilimumab) inhibitors before undergoing an allo-HSCT.