Abatacept and Ptcy Based Gvhd Prophylaxis with CNI/Sirolimus for Haploidentical HCT: Donor KLRC2 Genotype Impacts Outcome

Background: Abatacept (Abata, CTLA4Ig), an inhibitor of a key T cell costimulation pathway has recently been approved for GVHD prophylaxis following unrelated donor HCT in combination with CNI/MTX. In 2015, we had developed a novel protocol combining Abata and PTCy for HCT from haploidentical family donors (HFD). We analysed the impact of donor immunogenetics and immune reconstitution on the long-term outcome of 182 patients receiving HFD-HCT on this protocol.