Exatecan Mesylate in Treating Patients With Advanced Soft Tissue Sarcoma

DISEASE CHARACTERISTICS: Histologically confirmed soft tissue sarcoma Malignant fibrous histiocytoma Liposarcoma Rhabdomyosarcoma Synovial sarcoma Malignant paraganglioma Fibrosarcoma Leiomyosarcoma Angiosarcoma including hemangiopericytoma Malignant peripheral nerve sheath tumor Unclassified sarcoma Miscellaneous sarcoma including mixed mesodermal tumors of the uterus The following tumor types are excluded: Gastrointestinal stromal tumor Chondrosarcoma Malignant mesothelioma Neuroblastoma Osteosarcoma Ewing's sarcoma Embryonal rhabdomyosarcoma Prior chemotherapy for metastatic disease required One line of combination chemotherapy containing anthracycline OR No more than 2 single-agent regimens including anthracycline Adjuvant chemotherapy not considered first line unless tumor progresses within 6 months after treatment Must have 1 measurable lesion Clinical evidence of progression within 6 weeks prior to study Osseous lesions and pleural effusions not considered measurable No known or symptomatic CNS metastases PATIENT CHARACTERISTICS: Age: 15 to 75 Performance status: WHO 0-1 Life expectancy: Not specified Hematopoietic: WBC at least 4,000/mm^3 Platelet count at least 100,000/mm^3 Hepatic: Bilirubin no greater than 1.8 mg/dL Albumin at least 2.5 g/dL Renal: Creatinine no greater than 1.4 mg/dL OR Creatinine clearance greater than 65 mL/min Cardiovascular: No history of severe cardiovascular disease Other: Not pregnant Negative pregnancy test Fertile patients must use effective contraception during and for up to 6 months after study participation No other severe medical illness, including psychosis No other prior or concurrent malignancy except adequately treated basal cell skin cancer or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics More than 4 weeks since prior chemotherapy No other concurrent cytotoxic therapy Endocrine therapy: Not specified Radiotherapy: No radiotherapy to the sole measurable lesion No concurrent radiotherapy Surgery: Not specified Other: No other investigational drugs for 28 days prior to, during, and for 28 days after completion of study drug No other concurrent anticancer therapy