The role of allogeneic HSCT after CAR T cells for acute lymphoblastic leukemia

Enthusiasm with results of early phase trials using chimeric-antigen-receptor (CAR)-T cells targeting CD19 have led to fast approval of this novel immunotherapy for the treatment of acute lymphoblastic leukemia and diffuse large B-cell lymphoma, and to an explosion of clinical trials with such cells. Despite potential for long-term immune surveillance by CAR-T cells, many patients treated on these trials are referred to a consolidative hematopoietic stem cell transplantation, as are all patients responding to CAR-T cells in a study we conducted. Overall, paucity of long-term data and lack of randomized trials focusing on consolidative HSCT impact clinical evidence. Nevertheless, limited T cell persistence and inherent leukemia resistance mechanisms have led us, as well as others, to this clinical decision making, and are hereby reviewed.