DISEASE CHARACTERISTICS: Histologically confirmed recurrent, metastatic, or unresectable ovarian, tubal, or peritoneal carcinoma that is refractory to platinum, taxane, and topotecan Must have received at least 1 prior chemotherapy regimen Resistance to platinum, taxane, and topotecan is defined as the following: Progressive disease while on chemotherapy OR Relapse within six months of completing chemotherapy OR Failure to achieve complete response after six courses of chemotherapy No recurrent or metastatic disease amenable to attempted curative therapy with surgery and/or radiotherapy Measurable disease No brain metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT or SGPT no greater than 2 times upper limit of normal (ULN) (5 times ULN if liver metastases present) Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No active congestive heart failure No uncontrolled angina No myocardial infarction within past 6 months Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No concurrent serious infection No psychiatric disorder or mental disability No other malignancy within past 5 years, except: Nonmelanomatous skin cancer Carcinoma in situ of the cervix No other life threatening illness No history of camptothecin derivative allergy

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent biologic therapy Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy No concurrent radiotherapy Surgery: See Disease Characteristics At least 4 weeks since prior surgery No concurrent surgery Other: At least 4 weeks since other prior investigational drugs No other concurrent investigational drugs and for 4 weeks after study treatment