Ifosfamide With or Without O(6)-Benzylguanine in Treating Patients With Unresectable, Metastatic Solid Tumors

This randomized phase I trial is studying the side effects and best dose of O(6)-benzylguanine when given together with ifosfamide and to see how well it works compared to ifosfamide alone in treating patients with unresectable metastatic solid tumors. Drugs used in chemotherapy, such as ifosfamide and O(6)-benzylguanine, work in different ways to stop tumor cells from dividing so they stop growing or die. Combining ifosfamide with O(6)-benzylguanine may kill more tumor cells