Sphingomyelin/cholesterol liposomal vincristine: a new formulation for an old drug

Sphingomyelin/cholesterol liposomal vincristine (SV) is a novel formulation of vincristine encapsulated in the aqueous interior of liposomes composed of sphingomyelin and cholesterol. Benefits of the liposomal formulation include prolongation of the circulation half-life of total vincristine and an increase in drug delivery to sites of tumour growth resulting in enhanced efficacy. In addition, higher doses of vincristine than ordinarily administered can be prescribed without significant toxicity. Phase II studies have demonstrated that SV is active and well tolerated in relapsed diffuse large B cell lymphoma (DLBCL), including patients who have relapsed following an autologous stem cell transplant. SV has been successfully substituted for free vincristine in the CHOP regimen for those with previously untreated aggressive B cell non-Hodgkin's lymphoma, and is undergoing study in other settings. The achievement of responses in heavily pretreated patients with DLBCL and its low toxicity profile make SV a potential therapy for the palliative treatment of patients with multiply relapsed DLBCL. Ultimately, it is likely to be incorporated into combination chemotherapy regimens for use in untreated or relapsed patients. Its true value both as a single agent in heavily pretreated patients and in combination regimens will need to be established in Phase III trials.