The Oncologic Drugs Advisory Committee (ODAC) is meeting today to vote on whether the benefits outweigh the risks for Marqibo (vincristine sulfate liposomal injection) for the treatment of adult patients with Philadelphia chromosome negative (Ph-) acute lymphoblastic leukemia (ALL) whose disease has relapsed or who have previously undergone at least two other treatments with anti-leukemia drugs.
ALL more frequently affects children; only about 2,000 cases are diagnosed in adults in the US annually. About 70 percent of them are Philadelphia chromosome negative ALL.
It is an especially difficult disease to treat; in fact few treatments exist for this patient population, which is one of the arguments put forth by Talon pharmaceuticals, makers of Marqibo.
But Talon has an uphill battle, chiefly because the data submitted to the committee comes from a Phase II single-arm, open-label, dose-escalation trial of 65 patients. The FDA has always been clear about its heavy preference for randomized controlled trials and for not thinking much of single-arm trials.
Either way, Marqibo confers added survival of a few months in less than 20 percent of those who receive it. Furthermore, patients with relapsed Ph- ALL have a grim five-year survival rate of 7 percent.