DISEASE CHARACTERISTICS:

• Histologically confirmed soft tissue sarcoma that is not amenable to surgery, radiotherapy, or combined modality therapy with curative intent

• Stratum I

  • Malignant fibrous histiocytoma
  • Liposarcoma
  • Rhabdomyosarcoma
  • Synovial sarcoma
  • Malignant paraganglioma
  • Fibrosarcoma
  • Leiomyosarcoma
  • Angiosarcoma including hemangiopericytoma
  • Malignant peripheral nerve sheath tumor
  • Unclassified sarcoma
  • Miscellaneous sarcoma

• Stratum II

  • Gastrointestinal stromal tumor
  • Previously treated with imatinib mesylate for locally advanced or metastatic disease and demonstrated disease progression

• The following sarcoma types are excluded:

  • Mixed mesodermal tumors of the uterus (and carcinosarcoma)
  • Chondrosarcoma
  • Malignant mesothelioma
  • Neuroblastoma
  • Osteosarcoma
  • Ewing's sarcoma
  • Embryonal rhabdomyosarcoma
• At least one measurable lesion
• Progressive disease after 1 prior anthracycline- and/or alkylating-containing chemotherapy regimen for locally advanced or metastatic disease
• Clinical evidence of progression within 6 weeks prior to study treatment
• No known or symptomatic CNS metastases

PATIENT CHARACTERISTICS:

Age:

• Over 15

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 1.25 times upper limit of normal (ULN)
• SGPT and SGOT no greater than 3 times ULN
• Alkaline phosphatase no greater than 2.5 times ULN

Renal:

• Creatinine no greater than 1.4 mg/dL OR
• Creatinine clearance greater than 65 mL/min

Cardiovascular:

• No prior severe cardiovascular disease

Other:

• Not pregnant
• Negative pregnancy test
• Fertile patients must use effective contraception during and for up to 6 months after study
• No other prior or concurrent malignancy except adequately treated basal cell skin cancer or carcinoma in situ of the cervix
• No other severe medical illness
• No psychosis

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent biologic response modifiers or immunotherapy
• No concurrent prophylactic hematopoietic growth factors (e.g., filgrastim (G- CSF) or sargramostim (GM-CSF)

Chemotherapy:

• See Disease Characteristics
• More than 4 weeks since prior chemotherapy and recovered
• Prior adjuvant chemotherapy as first-line treatment allowed provided disease progressed within 6 months after the completion of chemotherapy
• No prior ecteinascidin 743 (stratum I)
• No other concurrent chemotherapy

Endocrine therapy:

• No concurrent hormonal therapy

Radiotherapy:

• See Disease Characteristics
• Recovered from prior radiotherapy
• No prior radiotherapy to sole measurable lesion
• Concurrent palliative radiotherapy to nontarget lesions allowed at investigator's discretion

Surgery:

• See Disease Characteristics
• Recovered from prior surgery

Other:

• No other concurrent anticancer therapy (approved or investigational)
• No concurrent participation in any other clinical treatment study
• No other concurrent investigational drugs