CAR‐T therapy as a consolidation in remission B‐ALL patients with poor prognosis

BACKGROUND: To date, almost all studies regarding chimeric antigen receptor (CAR)‐T cell therapy for B‐cell acute lymphoblastic leukemia (B‐ALL) were performed in refractory/relapsed (r/r) or minimal residual disease‐positive patients. CAR‐T therapy in remission patients has not been reported. AIM: To observe the treatment outcome of CAR‐T cells for remission B‐ALL patients with poor prognosis. METHODS AND RESULTS: CAR‐T treatment was applied to two B‐ALL patients in remission status who had poor prognostic factors and refused transplantation, and one case was unable to accept standard chemotherapy owing to multiple complications. The procedure of CAR‐T therapy in these two remission patients was the same as that in r/r B‐ALL patients. Lentiviral vectors encoding second generation CARs composed of CD3ζ and 4‐1BB were used to produce CAR‐T cells. Lymphodepleting agents fludarabine and cyclophosphamide were administered prior to cell infusion. Grade I cytokine release syndrome occurred after each T‐cell infusion and there was no neurotoxicity. CAR‐T treatment followed by non‐intensive maintenance chemotherapy and targeted drugs allowed both patients to obtain a long‐term event‐free survival of more than three and a half years without transplantation. CONCLUSIONS: CAR‐T therapy could be used in high‐risk B‐ALL patients as a consolidation to avoid transplantation, the combination of CAR‐T and following maintenance therapy may be better than CAR‐T alone for durable remission.