“For adult patients with B-cell ALL whose cancer has not responded to initial treatment or has returned after treatment, life expectancy is typically low,” said Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence, in a press release. “These patients have few treatments available and today’s approval provides a new, targeted treatment option.”
The B-cell precursor ALL develops when the bone marrow produces an abnormally large amount of B-cell lymphocytes. Besponsa is a CD22-antibody therapy that functions by binding to the ALL cancer cells that display the CD22 antigen on their surface. Through this binding, the drug initiates a response which resulting in the attenuation of growth of these cancer cells.
The safety and efficacy of Besponsa was evaluated in a Phase 3 INO-VATE clinical trial (NCT01564784), a randomized, international study of 218 patients with relapsed or refractory B-cell ALL with a history of one or two prior treatments. Patients were randomized to receive either Besponsa or a different chemotherapy. Of the evaluated patients, 35.8% that were administered Besponsa experienced complete remission for a median of 8.0 months, while 17.4% of patients on alternative chemotherapy experienced complete remission for a median of 4.9 months.
“The approval of Besponsa is an important step forward for adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia, a rare disease that can be fatal within a matter of months if left untreated,” said Liz Barrett, global president of Pfizer Oncology, in a press release. “Besponsa will help address a significant need for new treatment options in B-cell acute lymphoblastic leukemia, and may help more patients reach stem cell transplant, which provides the best chance for long term remission.”
The FDA had previously granted Besponsa Priority Review, Breakthrough therapy, and Orphan Drug designation. The U.S. labeling includes a boxed warning on the potential for hepatoxicity, which includes blockage of veins in the liver, known as veno-occlusive disease. If hepatoxicity is observed in patients taking Besponsa, then the treatment should either be stopped or the dose should be lowered. Another boxed warning indicates that there is an increased risk of death in patients taking Besponsa if they receive post–hematopoietic stem cell transplant.