Multiple relapsed acute lymphoblastic leukemia (ALL) has a very poor cure rate, and there is no standard of care for treatment of these patients. Therefore, we want to combine two chemotherapy drugs to see if they are safe and will help treat these patients. The first agent, L-asparaginase, is used in most patients during their initial treatment for ALL. The second agent, sirolimus, causes death in human leukemia cells in the laboratory. Sirolimus is also used in children who have received kidney or heart transplants to prevent organ rejection. Therefore, the safety and side effects are well known in children.