Blincyto Approval Expanded for Acute Lymphoblastic Leukemia Subgroup

The U.S. Food and Drug Administration (FDA) has granted accelerated approval to blinatumomab (Blincyto).

The drug is now indicated for the treatment of adults and children with B-cell precursor acute lymphoblastic leukemia (ALL) who are in remission, but still have minimal residual disease (MRD), which is defined as the presence of cancer cells below a level that can be seen under a microscope. As reported in a New England Journal of Medicine article earlier this week, the presence of MRD in leukemia can be directly related to increased risk of relapse.

The new indication for blinatumomab was approved under the accelerated approval pathway, under which the FDA may approve drugs for serious conditions where there is unmet medical need, and the drug is proven to have certain effects that are likely to provide a clinical benefit to patients.

“This is the first FDA-approved treatment for patients with MRD-positive ALL,” said Richard Pazdur, M.D., 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 in the official FDA press release.

In July 2017, the FDA granted full approval of the drug to treat relapsed or refractory B-cell precursor ALL in adults and children. That approval was based on results from the Phase 3, randomized, active-controlled, open-label TOWER study involving 405 adult patients with Ph- relapsed or refractory B-cell precursor ALL.

“Because patients who have MRD are more likely to relapse, having a treatment option that eliminates even very low amounts of residual leukemia cells may help keep the cancer in remission longer. We look forward to furthering our understanding about the reduction in MRD after treatment with Blincyto. Studies are being conducted to assess how Blincyto affects long-term survival outcomes in patients with MRD.”

The drug operates by attaching to CD19 protein on the leukemia cells and the CD3 protein found on certain immune system cells. By bringing the immune cell close to the leukemia cell, the immune cell can more effectively attack. Efficacy of blinatumomab in MRD-positive ALL was demonstrated in a single-arm clinical trial that enrolled 86 patients in first or second complete remission who had detectable MRD in at least 1 out of 1,000 cells in their bone marrow. Efficacy was based on achievement of undetectable MRD in an assay that could detect at least one cancer cell in 10,000 cells after one cycle of treatment, in addition to the length of time that the patients remained alive and in remission.

Overall, undetectable MRD was achieved by 70 (81%) of patients. More than half of patients remained alive and in remission for at least 22.3 months.

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