Bellicum touts promising T-cell therapy data, but U.S. program remains on hold

Bellicum Pharmaceuticals announced interim phase 2 data of its T cell therapy in children with acute myeloid leukemia (AML) and primary immunodeficiencies. The data show that the treatment, BPX-501, “may contribute” to a long-lasting anticancer effect in AML, the company said.

BPX-501 is an adjunct T cell therapy given to patients after they receive a transplant of haploidentical hematopoietic stem cells, or stem cells that match the patients’ tissue type and can develop into any type of blood cell. The treatment has a built-in “safety switch” called CaspaCIDe, which can be triggered to kill the engineered T cells if they cause side effects, like Graft-versus-host disease.

At the one-year mark, the study posted high rates of relapse-free survival and overall survival in 38 AML patients: 91.5% and 97.3% respectively.

“The recurrence of cancer is one of the most serious risks to AML patients receiving a stem cell transplant. These impressive results in children with AML suggest that BPX-501 may be effectively reducing or eradicating residual cancer cells following a haplo-transplant procedure,” said Neena Kapoor, M.D., director of the Blood and Marrow Transplantation Program at Children’s Hospital of Los Angeles and an investigator in the trial.

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The data for 59 patients with primary immunodeficiencies (PIDs) were also encouraging—for patients with Severe Combined Immunodeficiency, Wiskott-Aldrich syndrome, Chronic Granulomatous Disease and other rare immune deficiencies, the disease-free survival rate was 88.1% and overall survival was 88.6% after one year.

“Delayed immune reconstitution can lead to severe infectious complications, a major cause of morbidity and mortality in PID patients who undergo a T-depleted [haploidentical hematopoietic stem cell transplant]. BPX-501 donor T cells administered after a transplant support immune recovery in these patients, and the CaspaCIDe safety switch engineered into BPX-501 may provide a critical safety net to address the risk of uncontrolled [Graft-versus-host disease] from donor T cells,” Kapoor said.

Bellicum is working with the FDA on a potential registration study for pediatric patients in the U.S. and hopes to start it by the end of the year. But that depends on the agency lifting a clinical hold it placed on all U.S. trials of BPX-501 in January, after learning of three cases of brain damage that were possibly related to the treatment. Barely a week after the FDA set the hold, Bellicum reinforced its leadership, adding Genentech alum William Grossman as chief medical officer.