Efficacy and Safety of Vincristine Sulfate Liposome Injection in the Treatment of Adult Acute Lymphocytic Leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous group of hematologic malignancies that arise from clonal proliferation of immature lymphoid cells in the bone marrow, peripheral blood, and other organs. The vinca alkaloid vincristine is a standard component of chemotherapy regimens used to treat ALL, because of its well-defined mechanism of action, demonstrated anticancer activity, and ability to be combined with other agents. However, the dosage of vincristine is frequently capped because of neurotoxicity concerns, and patients with large body surface areas are, therefore, almost always underdosed. Liposomal formulations have the ability to "passively" accumulate at sites of increased vasculature permeability and reduce the adverse effects of encapsulated relative to free drug. Vincristine sulfate liposome injection (VSLI) is a sphingomyelin/cholesterol-based liposome-encapsulated formulation that is delivered weekly in a 1-hour infusion. Based on the pharmacokinetics of the liposomal delivery system, vincristine is slowly released from the liposome and delivered into the tissues more efficiently than with the standard preparation, allowing a higher dose. This increase in therapeutic index from reduced toxicity is a valuable difference between the two formulations. VSLI is indicated for the treatment of adults with second or greater relapse and clinically advanced Philadelphia chromosome-negative ALL. For the first time, studies will be able to exploit the delivery of higher and uncapped doses of vincristine in randomized studies comparing first-line chemotherapy with standard vincristine versus VSLI in both ALL and lymphoma to determine whether VSLI is superior to conventional vincristine.