The FDA has granted approval to obecabtagene autoleucel (Aucatzyl) for the treatment of adult patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). This approval marks a significant advancement in the treatment landscape for ALL, addressing a critical unmet need for patients who have exhausted other treatment options. The decision was based on the promising results of the phase 1/2 FELIX trial (NCT04404660), which demonstrated a clinically meaningful response in this challenging patient population.
FELIX Trial Results
The pivotal FELIX trial evaluated the safety and efficacy of obecabtagene autoleucel in patients with CD19-positive B-cell ALL who had relapsed after prior therapies or were refractory to treatment. The topline data from the trial revealed a complete response (CR) rate of 42% (95% CI, 29%-54%) within 3 months of treatment. Furthermore, the median duration of CR within 3 months was 14.1 months (95% CI, 6.1-not reached), indicating a potential for durable remission in responding patients.
Clinical Perspective
Elias Jabbour, MD, a professor of medicine at The University of Texas MD Anderson Cancer Center and an investigator in the FELIX trial, expressed enthusiasm about the approval, stating that obecabtagene autoleucel fills a major need in ALL therapy, where outcomes after relapse are often poor. He suggested that this therapy could potentially replace transplants in inducing durable remissions, although further follow-up is needed to confirm this.
Dosage and Administration
The recommended dose of obecabtagene autoleucel is 410x106 CD19 CAR-positive viable T cells, administered as a split dose infusion on days 1 and 10 (± 2 days). Prior to infusion, patients undergo lymphodepleting chemotherapy with fludarabine and cyclophosphamide. A bone marrow blast assessment is also performed.
Safety Profile
The press release included a boxed warning for cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and T-cell malignancies. In the clinical trial, 75% of patients experienced CRS, with 3% having grade 3 CRS. Neurologic toxicities occurred in 64% of patients, with 12% experiencing grade 3 or higher toxicities. ICANS was observed in 24% of patients, with 7% being grade 3 or higher. These potential risks necessitate careful monitoring and management of patients receiving obecabtagene autoleucel.
