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