Role of allogeneic hematopoietic cell transplantation after anti-CD19 CAR T-cell treatment: Guidelines from the SFGM-TC

The role of allogeneic hematopoietic cell transplantation (allo-HCT) after CAR T-treatment cells in hematologic malignancies is currently controversial. Prolonged remissions after several years of follow-up suggest that there is a curative effect of CAR T-cells therapy, whereas allo-HCT was previously considered the only curative treatment in relapse situation. The aim of this harmo-nization workshop is to detail the existing data in the literature on the feasibility of allo-HCT after CAR T-cells and to propose to consider allograft in selected patients with B-acute lymphoblastic leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). In B-ALL, various intrinsic factors (inherent to the patient, to the disease, to the type of CAR T-cells) and especially various post CAR T-cells criteria (early expansion kinetics, residual disease at D28, early loss of B-cell aplasia) should lead to consider performing allo-HCT before the occurrence of a relapse. In DLBCL, although there are risk factors for relapse at diagnosis and prior to CAR T-cells therapy, response assessed by PET-CT at three months is critical and allo-HCT cannot currently be recommended in cases of complete or partial remission. In any case, if the age is appropriate for allogeneic transplantation, HLA typing should be performed before CAR T-cells treatment in order not to delay the allo-HCT project if needed.