Marqibo (liposomal vincristine) is a form of vincristine preparation. Vincristine is designed to interfere with the multiplication of cancer cells, which may slow or stop their growing and spreading throughout the body. This may cause the cancer cells to die. Liposomal vincristine is formed when vincristine is placed inside of oil droplets called liposomes, which may help to improve the delivery of drug to the tumor site. The liposomal formulation results in a slow, steady release of vincristine in the tumor metastasis, exposing the cancer cells to vincristine continuously.