Alemtuzumab With or Without Methotrexate and Mercaptopurine in Treating Young Patients With Relapsed Acute Lymphoblastic Leukemia

This phase II trial is studying how well giving alemtuzumab with or without methotrexate and mercaptopurine works in treating young patients with relapsed acute lymphoblastic leukemia. Monoclonal antibodies such as alemtuzumab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Drugs used in chemotherapy, such as methotrexate and mercaptopurine, work in different ways to stop cancer cells from dividing so they stop growing or die. Combining monoclonal antibody therapy with chemotherapy may kill more cancer cells.