Adult patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL) have a new targeted treatment option, following the US Food and Drug Administration's (FDA) approval of Besponsa (inotuzumab ozogamicin). The drug, developed by Pfizer, was granted Priority Review, Breakthrough Therapy and Orphan Drug designations by the FDA.
Besponsa is a targeted therapy believed to work by blocking the growth of cancerous cells by binding to the B-cell ALL cancer cells expressing the CD22 antigen. B-cell precursor ALL is a rapidly progressing form of cancer that will be diagnosed in around 6,000 people in the US this year, according to National Cancer Institute estimates.
Richard Pazdur, MD, director of the FDA's Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, commented: "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… These patients have few treatments available and today's approval provides a new, targeted treatment option."
Other treatments for relapsed and refractory B-cell precursor ALL are also available, for example, it may be treated with allogeneic stem cell transplantation if a matched donor is available. Drugs not used in the first round of treatment may also be tried. Medication already approved by the FDA for the treatment of relapsed and refractory B-cell precursor ALL include Marqibo (liposomal vincristine), Arranon (nelarabine), Blincyto (blinatumomab), and Clolar (clofarabine).
The efficacy and safety of Besponsa were demonstrated in a clinical trial of 326 patients with either relapsed or refractory B-cell ALL leukemia, all of whom had received up to two prior treatments. Relapsed leukemia is the return of ALL cells in the bone marrow and a decrease in the levels of normal blood cells following remission. Refractory leukemia is when patients still have ALL cells in the bone marrow following treatment.
The clinical trial demonstrated more than one-third of those treated with Besponsa experienced complete remission for a median of eight months. This was significantly more than patients relieving an alternative chemotherapy treatment, 17 percent of whom experienced complete remission for a median of 5.9 months.
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