CAR T-cells for T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) has a dismal prognosis in case of relapsed or refractory disease. Contrary to B-ALL, few immunotherapies are available for T-ALL. Use of autologous CAR T-cells is challenging due to shared antigen between leukemic and normal T-cells responsible for fratricide and T-cell aplasia in case of persistence of CAR T-cells. Moreover, risk of contamination of the apheresis product by lymphoblasts remains an issue. To counteract these challenges several methods are used to edit T-cell such as protein expression blocker, CRISPR/Cas9 and base-editing. Other possibility is to use autologous T-cells naturally selected in vitro or donor-derived T-cells allowing gene edition and reduction of the risk of graft vs host disease. Encouraging results are obtained in preclinical and clinical studies for early response rate but several questions remain. Is the persistence of these cells requiring for maintaining the remission? Is it feasible to recover a target-negative T-cell population without risk of profound immunosuppression? Has an allogeneic stem cell transplantation to be planned for patients after CAR T-cells infusion? What about the risk of engineered T-cells in the long term?