Pfizer locks down US approval for Besponsa
- Pfizer Inc. has secured Food and Drug Administration approval for Besponsa as a treatment for adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL).
- The agency based the approval on results from the Phase 3 INO-VATE ALL trial, which compared Besponsa with investigators' choice of chemotherapy. Complete remission rate for patients treated with Besponsa was 81%, compared with 29% in the chemotherapy arm. Nearly 80% of Besponsa patients and nearly 30% of chemotherapy patients showed minimal residual disease (MRD) negativity.
- Besponsa's label carries a boxed warning for hepatotoxicity and an increased risk of post-hematopoietic stem cell transplantation non-relapse mortality.
Cancer cells have a wide variety of molecules known as cell surface antigens (CSAs) that can trigger immune responses. As the immuno-oncology field has heated up, so too has drugmakers' interest in CSA-targeting medicines.
Besponsa (inotuzumab ozogamicin), for instance, is an antibody-drug conjugate (ADC) specifically targeting one CSA known as CD22. Novartis AG's CAR-T therapy tisagenlecleucel targets another one, CD19. Other CAR-T therapies in development, though, also target CD22.
In the U.S. in 2017, around 5,970 people will be diagnosed with B-cell precursor ALL, an aggressive form of leukemia. About 1,440 will die from the disease this year, according to the National Cancer Institute. While the early response rate to treatment is good — with about 80% to 90% of adult patients experiencing complete remission at during initial treatment, according to Pfizer — the relapse rate is high, and the median overall survival in relapsed patients is around five months.
"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, director of the FDA’s Oncology Center of Excellence, in an Aug. 17 statement from the agency. "These patients have few treatments available and [Besponsa's] approval provides a new, targeted treatment option."
The aim for treatment in relapsed or refractory disease is to achieve complete remission, allowing patients to have further treatment to maintain remission, such as stem cell transplant.
"Based on the results seen in the INO-VATE ALL trial, Besponsa improved multiple efficacy measures, including rates of hematologic remission, MRD-negativity and stem cell transplantation," Hagop Kantarjian, lead investigator for the INO-VATE ALL study, said in an Aug. 17 statement from Pfizer.
Pfizer initially developed Besponsa through a collaboration with Celltech Group plc (which was later acquired by UCB S.A.). Per terms of the agreement, Pfizer holds full manufacturing and clinical development rights to the drug. In June, the European Medicines Agency approved Besponsa for relapsed or refractory CD22-positive B-cell precursor ALL. Two months earlier, it had received a positive opinion from the Committee for Medicinal Products for Human Use of the European Medicines Agency.
Besponsa has Breakthrough Therapy and Priority Review designations, and is the first CD22-directed ADC to be approved for this indication, according to Pfizer.
- Pfizer Inc. Press release
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