Delayed remission following sequential infusion of humanized CD19-and CD22-modified CAR-T cells in a patient with relapsed/refractory acute lymphoblastic leukemia and prior exposure to murine-derived CD19-directed CAR-T cells

Background: CD19-modified CAR-T cells greatly influence responses in patients with relapsed/refractory acute lymphoblastic leukemia (ALL). However, recurrence remains a challenge, and reinfusion of CAR-T cells is not always effective. Sequential infusion of humanized CD19-modified and CD22-modified CAR-T cells may overcome this issue and induce remission. Methods: We examined treatment with sequential infusion of humanized CD19-modified and CD22-modified CAR-T cells in a patient with relapsed ALL previously exposed to murine-derived anti-CD19 CAR-T cells. Results: At similar to 6 weeks after treatment, repeated bone marrow smear and flow cytometry analysis revealed no lymphoblasts. Conclusion: Our results suggest that sequential infusion of humanized CD19-modified and CD22-modified CAR-T cells is a valuable option for relapsed patients with prior infusion of murine-derived, CD19-directed CAR-T cells.