DISEASE CHARACTERISTICS: Histologically or cytologically confirmed stage III or IV ovarian epithelial cancer Platinum resistant disease as defined by disease progression during or within 6 months of receiving prior paclitaxel combined with cisplatin or carboplatin No elevated CA-125 as only evidence of disease recurrence Measurable disease At least 20 mm in diameter by conventional techniques OR At least 10 mm in diameter by spiral CT scan No known brain metastases

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

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: Not specified Other: No other concurrent therapeutic agents for cancer