WASHINGTON – The FDA has approved vincristine sulfate liposome injection for the treatment of a rare blood and bone marrow cancer. in a statement, the FDA said the drug is indicated for the treatment of Philadelphia chromosome-negative adults with acute lymphoblastic lymphocytic leukemia (ALL) who have relapsed or whose disease has progressed despite two or more anti-leukemia treatments. leukemia (ALL). This disease (ALL) is a “rapidly progressive” cancer of the blood and bone marrow that is more common in children than in adults. The orphan drug, which is administered intravenously once a week, received accelerated approval from the FDA, which refers to drugs used to treat fewer than 200,000 patients nationwide. During the approval process, the manufacturer also received tax credits and patient cost reductions (policy benefits) for the drug. Approval of the drug was fraught with uncertainty as an FDA advisory panel questioned its efficacy. The panel, however, reluctantly agreed to recommend the drug for approval. Three complete sets of trials including 148 patients evaluated the drug’s safety and efficacy. In one set of trials, 65 patients with leukemia who had received two or more standard therapies and relapsed showed good results, with at least one of the prior therapies lasting 90 days or longer to have an effect. The median period of complete remission in 15.4% of subjects with or without incomplete recovery of blood cell counts was 28 days, and the median time to relapse, death, or first presentation with the next treatment was 56 days. In both safety evaluation trials, common side effects were constipation, nausea, hematocrit, fever, nerve damage, fatigue, diarrhea, decreased appetite and insomnia. 76% of patients experienced serious side effects, including decreased white blood cells with fever, hypotension, respiratory distress and cardiac arrest. Marqibo will carry a black box warning stating that it is for intravenous use only and that other routes of administration may be fatal. The warning also alerts health care providers to the potential risk of overdose due to varying dosages of vincristine sulfate in individual applications. The product is manufactured by Talon Pharmaceuticals of South San Francisco, Calif.