OUTLINE: Patients are stratified into 5 groups according to renal and hepatic function: Group 1: Normal renal function and normal hepatic function Group 2: Moderate renal impairment and normal hepatic function Group 3: Severe renal impairment and normal hepatic function Group 4: End stage renal impairment and normal hepatic function Group 5: Normal renal function and moderate hepatic impairment Group 1: Patients receive 506U78 IV over 2 hours on days 1, 3, and 5. Groups 2-5: Patients receive 506U78 IV over 2 hours on days 1, 3, and 5. Dose escalation occurs independently in each of the treatment groups. Cohorts of 3-6 patients receive escalating doses of 506U78 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose limiting toxicities. Treatment repeats every 4 weeks for a maximum of 6 courses in the absence of unacceptable toxicity or disease progression.