CP4071 in Treating Patients With Locally Advanced or Metastatic Soft Tissue Sarcoma

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed soft tissue sarcoma * Metastatic or locally advanced * Failed at least 1 prior therapy * Measurable disease outside prior irradiation field * No CNS metastases PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * SWOG 0-2 Life expectancy: * Not specified Hematopoietic: * Not specified Hepatic: * Bilirubin no greater than 2 times upper limit of normal (ULN) Renal: * Creatinine less than 1.5 times ULN * Calcium less than ULN * Potassium normal Other: * No other malignancy within the past 5 years except stage I or II cancer in complete remission, carcinoma in situ of the cervix, or basal cell or squamous cell skin cancer * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * Prior biologic response modifier therapy allowed Chemotherapy: * No more than 3 prior chemotherapy regimens for advanced, recurrent, or metastatic disease * No other concurrent chemotherapy Endocrine therapy: * No concurrent hormonal therapy for malignancy Radiotherapy: * See Disease Characteristics * At least 3 weeks since prior radiotherapy and recovered * No concurrent radiotherapy Surgery: * At least 4 weeks since prior surgery and recovered Other: * No other concurrent cardiac glycosides