New Treatment Approved for Chronic Myelogenous Leukemia
The Food and Drug Administration has approved omacetaxine mepesuccinate (Synribo) to treat adults with chronic myelogenous leukemia (CML) whose cancer has progressed after treatment with at least two tyrosine kinase inhibitors (TKIs).
Omacetaxine mepesuccinate interferes with the ability of cancer cells to make proteins. The drug is injected just under the skin twice daily for 14 consecutive days over a 28-day cycle until white blood cell counts return to normal. It is then administered twice daily for 7 consecutive days over a 28-day cycle as long as patients continue to benefit.
The drug’s effectiveness was evaluated using a combined cohort of patients whose cancer progressed after previous treatment with two or more TKIs. All of the patients were treated with omacetaxine mepesuccinate.
In 14 of 76 patients with chronic phase CML (18.4 percent), the percentage of cells expressing the Philadelphia chromosome genetic mutation fell within 3.5 months, on average. The median duration of the reduction was 12.5 months.
In 5 of 35 patients with accelerated phase CML (14.3 percent), white blood cell counts normalized or the patient had no evidence of leukemia, within 2.3 months, on average. The median duration of the response in these patients was 4.7 months.
The most common side effects reported during the clinical studies included a low level of platelets in the blood; a low red blood cell count; a decrease in neutrophils, which may lead to infection, fever, diarrhea, nausea, weakness, and fatigue; a reaction at the injection site; and a drop in lymphocytes in the blood.
Omacetaxine mepesuccinate was approved under the FDA’s accelerated approval program, which provides patients access to promising new drugs while the company conducts additional clinical studies to confirm the drug’s clinical benefit and safe use. The drug also received orphan-product designation by the FDA because it is intended to treat a rare disease or condition.