FDA Approves Obe-cel for B-Cell Acute Lymphoblastic Leukemia (ALL)

Last week the FDA approved obe-cel (obecabtagene autoleucel), a CAR T-cell therapy to treat adults with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL). 

This is the seventh CAR T-cell therapy FDA has approved and the third for a form of B-ALL.

ALL is a cancer where the bone marrow makes too many lymphocytes, and B-ALL is the most common subtype. Current treatments for adults with B-ALL include chemotherapy and, for those who can tolerate it, allogeneic stem cell transplantation. But patients often face a poor prognosis, so this approval represents a huge step forward. 

Obe-cel is a CD19 CAR T-cell investigational therapy designed with a fast target binding off-rate to minimize excessive activation of the programmed T cells. Clinical trials have demonstrated that obe-cel’s fast off-rate reduces toxicity and T-cell exhaustion, resulting in improved persistence and high levels of durable remissions, according to the treatment’s developer, Autolus Therapeutics. 

The approval comes after impressive results from clinical trials. Efficacy was evaluated in FELIX (NCT04404660), an open-label, multicenter, single-arm trial that enrolled adults with relapsed or refractory CD19-positive B-cell ALL. Enrolled patients were required to have relapsed following a remission lasting 12 months or less, relapsed or refractory ALL following two or more prior lines of systemic therapy, or disease that was relapsed or refractory 3 or more months after allogeneic stem cell transplantation. 

The major efficacy outcome measures were rate and duration of complete remission (CR) achieved within three months after infusion. Additional outcome measures were rate and duration of overall complete remission which includes complete remission and complete remission with incomplete hematologic recovery (CRi), at any time. Of the 65 patients evaluable for efficacy, 27 patients (42%; 95% confidence interval [CI]: 29%, 54%) achieved CR within 3 months. The median duration of CR achieved within 3 months was 14.1 months (95% CI: 6.1, not reached). 

I’m hopeful that this treatment will offer significantly better outcomes to a patient population who needs it. Congratulations to everyone involved in developing this latest FDA approved cancer therapy, and continuing the extraordinary progress in our field. 

Paula Cannon, PhD, is the president of ASGCT (2024-25) and a Distinguished Professor of Molecular Microbiology & Immunology at USC's Keck School of Medicine.

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