FDA Approves New Drug for Chronic Myelogenous Leukemia

Nick Mulcahy

October 26, 2012

The US Food and Drug Administration (FDA) has approved omacetaxine mepesuccinate (Synribo, Teva Pharmaceuticals) for the treatment of adults with chronic myelogenous leukemia (CML), under its accelerated approval program. The indication is specifically for patients who progress after treatment with at least 2 tyrosine kinase inhibitors.

"Today's approval provides a new treatment option for patients who are resistant to or cannot tolerate other FDA-approved drugs for chronic or accelerated phases of CML," said Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research.

Omacetaxine mepesuccinate is subcutaneously injected twice daily for 14 consecutive days over a 28-day cycle until a hematologic response occurs and white blood cell counts normalize. The drug is then administered twice daily for 7 consecutive days over a 28-day cycle as long as the patient continues to clinically benefit.

The drug's effectiveness in chronic-phase CML was demonstrated by a reduction in the percentage of cells expressing the Philadelphia chromosome genetic mutation, which is found in most CML patients, according to the FDA. Fourteen (18.4%) of 76 patients achieved a reduction. The reduction occurred at 3.5 months, on average. The median length of the reduction was 12.5 months.

The effectiveness of omacetaxine mepesuccinate in accelerated-phase CML was determined by the number of patients who had a major hematologic response (normal white blood cell counts or no evidence of leukemia). Five (14.3%) of 35 patients achieved a major hematologic response in an average of 2.3 months, the median duration of which 4.7 months.

The most common adverse effects reported during clinical studies were thrombocytopenia; anemia; neutropenia and febrile neutropenia; diarrhea; nausea, weakness, and fatigue; injection-site reaction; and lymphopenia.

Omacetaxine mepesuccinate "is the second drug approved to treat CML in the past 2 months," Dr. Pazdur noted. In September, the FDA approved bosutinib (Bosulif, Pfizer) to treat patients with chronic-, accelerated-, or blast-phase Philadelphia-chromosome-positive CML who are resistant to or who cannot tolerate other therapies.