The U.S. Food and Drug Administration (FDA) has granted approval to Aucatzyl (obecabtagene autoleucel) for the treatment of adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). This approval marks a significant advancement in the treatment landscape for this aggressive cancer, offering new hope for patients with limited options. The decision was based on the encouraging results from the FELIX study, which demonstrated strong efficacy and manageable safety.
Efficacy and Safety Data
The FELIX study, a Phase Ib/II clinical trial (NCT04404660), evaluated the efficacy and safety of Aucatzyl in adult patients with relapsed or refractory CD19-positive B-cell ALL. The study enrolled patients who had relapsed after a remission lasting a year or less, relapsed or were nonresponsive following two or more prior lines of systemic therapy, or relapsed three or more months after an allogeneic donor stem cell transplant. Patients received chemotherapy to eliminate existing T-cells, followed by two infusions of Aucatzyl 10 days apart.
Results published in the New England Journal of Medicine indicated that Aucatzyl demonstrated a 76% overall response rate, with 55% of patients achieving remission. Among the 65 evaluable patients, 42% achieved complete remission within three months, with a median response duration of 14.1 months. Overall, 63% achieved complete remission at any time during the trial, including 12% who experienced complete remission with incomplete hematologic recovery.
According to Dr. Elias Jabbour, professor of leukemia with the University of Texas MD Anderson Cancer Center and lead U.S. investigator, "Patients with B-cell ALL need effective standalone treatment options, and [Aucatzyl] demonstrated strong long-term efficacy and response rates."
Mechanism of Action
Aucatzyl is a chimeric antigen receptor (CAR) T-cell therapy, a form of immunotherapy that modifies a patient's own T-cells to target and destroy cancer cells. In the case of Aucatzyl, T-cells are genetically engineered to recognize the CD19 protein, which is commonly found on the surface of cancerous B-cells. Once infused back into the patient, these modified T-cells seek out and eliminate B-cells expressing CD19.
Impact on Treatment Landscape
B-cell ALL affects the development of B-cells, white blood cells made in the bone marrow that help the body fight off infections. In B-cell ALL, the bone marrow produces abnormal, immature B-cells called lymphoblasts, which accumulate in the bone marrow and spread to other areas of the body. Approximately 75% of adults with ALL have the B-cell ALL subtype, with a five-year survival rate of around 40%.
The approval of Aucatzyl offers a crucial new treatment option for these patients. "Until now, these patients had limited treatment options," said Dr. Jabbour. "We observed minimal immunotoxicity and a strong persistence of CAR T-cells, which support [Aucatzyl] being the standard of care for this population."
Unlike some other CAR-T therapies, the FDA did not require a Risk Evaluation Mitigation Strategy (REMS) for Aucatzyl, reflecting its manageable safety profile. The most frequently reported adverse reactions included infections, fever, muscle and bone pain, diarrhea, neutropenia, fatigue, headache, and hemorrhage. While cytokine release syndrome (CRS) occurred in 75% of patients, only 3% experienced severe symptoms.
