FDA Approves Drug to Treat Rare Type of Leukemia
Last month, the Food and Drug Administration (FDA) approved vincristine sulfate liposome (Marqibo) to treat adults with a rare disease called Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL).
Vincristine sulfate liposome is approved for patients whose leukemia has returned at least twice or whose leukemia has progressed following two or more prior treatments. The drug contains vincristine, a common anticancer agent, encased within a liposome, a drug delivery vehicle composed of material similar to that of cell membranes. It is an injection administered once a week by a health care professional.
The drug’s effectiveness was evaluated in a clinical trial of adults whose leukemia had relapsed at least twice despite standard treatments and who had responded to at least one previous treatment for at least 90 days. Ten of the 65 enrolled patients (15.4 percent) had a complete remission or a complete remission with an incomplete blood count recovery. In these 10 patients, the remissions lasted for a median of 28 days. The median time to the first post-remission event (relapse, death, or next therapy) was 56 days.
The drug’s safety was evaluated in two single-arm trials that included 83 patients whose leukemia had relapsed at least twice. Serious adverse events, such as low white blood cell counts with fever, low blood pressure, respiratory distress, and cardiac arrest, occurred in 76 percent of the patients studied. The most common side effects included constipation, nausea, low blood cell counts, fever, nerve damage, fatigue, diarrhea, decreased appetite, and insomnia.
A warning that the drug must be administered intravenously because it is deadly if given in other ways, such as into the spinal fluid, will be included in the prescribing information. The warning also states that the dosage recommendations for vincristine sulfate liposome and vincristine sulfate are different. To avoid overdosing, health care professionals must verify the drug name and the dose before administration.
The drug was approved under the accelerated approval program, which allows the FDA to approve a drug based on clinical data showing that it is reasonably likely to provide a clinical benefit to patients. The manufacturer must conduct more clinical studies to confirm the drug’s benefit and safety. Vincristine sulfate liposome also received orphan-product designation because it is intended to treat a rare disease.