What is the efficacy of gene therapy for the treatment of acute lymphoblastic leukemia (ALL)?

Updated: Jul 02, 2021
  • Author: Karen Seiter, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Studies of treatment with CAR T-cells targeting CD19 have reported high rates of complete and long-lasting remissions in patients with refractory acute lymphoblastic leukemia (ALL). Toxicities, which can be fatal, include cytokine release syndrome (CRS), B-cell aplasia, and cerebral edema. [84]  

In August 2017, the US Food and Drug Administration (FDA) approved the anti-CD19 CAR T-cell therapy agent tisagenlecleucel (Kymriah) for the treatment of patients up to 25 years of age with B-cell precursor ALL that is refractory or in second or later relapse. Because of the risk of adverse effects, the FDA approval includes a risk evaluation and mitigation strategy, which requires special certification for hospitals and clinics that administer the treatment and additional training for their physicians and other staff. [85, 86]

Approval of tisagenlecleucel was based on the results of an open-label, muticenter single-arm trial (Study B2202) that included 88 children and young adults (median age, 12 years) with relapsed or refractory B-cell ALL. Of the treated patients evaluable for efficacy, 52 of 63 responded; of those, 40 patients (63%) had a complete response within the first 3 months after infusion, and 12 (19%) had a complete remission with incomplete blood count recovery. All of those had minimum residual disease–negative status in the bone marrow. [87]

In conjunction with the approval of tisagenlecleucel, the FDA also expanded the approval of tocilizumab to include the treatment of severe or life-threatening CRS resulting from CAR T-cell therapy in patients 2 years of age or older. In clinical trials, 69% of patients with CRS related to CAR T-cell therapy had complete resolution of CRS within 2 weeks after receiving one or two doses of tocilizumab. [86]

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