<qa>  What is the effect of a drug that enters the circulation when introduced into the body?This pilot phase II trial studies how well vincristine sulfate liposome works in treating patients with acute myeloid leukemia that has returned after a period of improvement or has not responded to previous treatment. Drugs used in chemotherapy, such as vincristine sulfate liposome, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Liposomal encapsulation prolongs bioavailability proportion of drug that enters the circulation when introduced into the body of vincristine sulfate, and may increase its delivery to cancer cells with fewer side effects. 