To Evaluate the Safety, Activity and Pharmacokinetics of Marqibo in Children and Adolescents With Refractory Cancer

Background: * Marqibo(Registered Trademark) is a new anticancer drug. It combines Vincristine sulfate, which is a widely used anticancer drug, and packages it into a tiny fat bubble known as a liposome. The goal of this is to improve the drug's ability to destroy cancer cells and help reduce the potential side effects of treatment. * Vincristine sulfate was originally developed from chemicals found in the periwinkle plant and acts against multiple types of malignant cancer. It is approved for multiple cancer types including solid tumors and blood cancers. * Research has shown that Marqibo(Registered Trademark) is able to slow or stop the growth of cancer cells in some adults, both alone and in combination with other chemotherapy drugs, but more research is needed to determine its use in children. * There has been one previous small study of Marqibo(Registered Trademark) in children. Although some anti-cancer activity was seen, side effects and optimal dosing were not fully determined. * As is seen with standard Vincristine suflate, the most common side effect of Marqibo(Registered Trademark) involves the nervous system. It can cause numbness and tingling in the hands and feet. Symptoms commonly improve when the drug is discontinued or the dose is lowered. Objectives: \- To determine the safety and efficacy of Marqibo as a treatment for children who have been diagnosed with certain types of malignant cancer that has not responded to standard treatment. Eligibility: * Children and adolescents between 2 and 21 years of age who have been diagnosed with certain types of malignant cancer that has not responded to standard treatment. * These cancer types include solids tumors, primary brain tumors, leukemias, and lymphomas.