Anti-CD22 chimeric antigen receptor (CAR) T-cell therapy is safe, feasible, and clinically active in children and young adults with relapsed/refractory acute lymphoblastic leukemia who have undergone prior CAR therapy.1

The study, which will be presented at the American Society of Hematology (ASH) 58th Annual Meeting & Exposition in San Diego, California, showed that 44% of 9 evaluable treated achieved complete marrow remission.

Of those, 7 had previously received treatment with anti-CD19 CAR T-cell therapy, 2 had received 2 prior transplantations, and all patients had undergone at least 1 prior allogeneic hematopoietic cell transplantation.

Six patients treated at dose level 1 required dose-escalation due to expansion at this level following dose-limiting toxicities in the second patient with grade 3 diarrhea. Three patients treated at dose level 2 without dose-limiting toxicities underwent dose escalation.

Researchers observed CAR expansion and cytokine release syndrome (CRS) in 6 patients with a maximum CRS grade 2, and detected CAR cells in the peripheral blood, cerebrospinal fluid, and bone marrow of all responders.

Investigators enrolled children and young adults with relapsed/refractory CD22+ hematologic malignancies. All patients underwent lymphodepleting chemotherapy with fludarabine on days –4, –3, and –2 and cyclophosphamide on day –2 followed by CAR T-cell infusion on day 0. Dose level 1 started at 3 x 105 transduced T-cells/kg and dose level 2 began at 1 x 106transduced T cells/kg.

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These interim findings suggest that anti-CD22 CAR T-cell therapy may be feasible for both CAR-naive patients and for those who have previously been treated with anti-CD19 CAR T-cell therapy who are CD19 negative. Accrual for the study is ongoing.

Reference

  1. Shah NN, Stetler-Stevenson M, Yuan CM, et al. Minimal residual disease negative complete remissions following anti-CD22 chimeric antigen receptor (CAR) in children and young adults with relapsed/refractory acute lymphoblastic leukemia (ALL). Paper presented at: American Society of Hematology (ASH) 58th Annual Meeting & Exposition; December 3-6, 2016; San Diego, CA.