PATIENT CHARACTERISTICS: Age: 21 and over Performance status: ECOG 0-2 Life expectancy: Greater than 3 months Hematopoietic: WBC at least 3,000/mm3 Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin normal AST and ALT no greater than 2.5 times upper limit of normal Renal: Creatinine normal OR Creatinine clearance greater than 60 mL/min Other: No history of allergic reactions to compounds of similar chemical or biologic composition to rebeccamycin analogue No other prior cancer within the past 5 years except nonmelanomatous skin cancer No other medical problems that would preclude study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception