DISEASE CHARACTERISTICS:

• Metastatic or inoperable malignancy for which there is no known curative or survival-prolonging palliative therapy or that has failed all such therapies

  • No leukemia or primary CNS tumors

• No active brain metastases, including:

  • No evidence of cerebral edema by CT scan or MRI
  • No progression from prior imaging study
  • No requirement for steroids
  • No related clinical symptoms

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• At least 2 months

Hematopoietic:

• WBC at least 3,000/mm^3
• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.5 mg/dL
• SGOT and SGPT no greater than 2.5 times upper limit of normal

Renal:

• Creatinine no greater than 1.5 mg/dL

Cardiovascular:

• No uncontrolled or significant cardiac disease
• No myocardial infarction within the past 6 months
• No significant congestive heart failure
• No prior clinically significant atrial or ventricular arrhythmia
• No prior second- or third-degree heart block
• No evidence of acute ischemia or prolonged QTc interval (greater than 450 ms) on electrocardiogram

Pulmonary:

• No uncontrolled or significant pulmonary disease

Other:

• No serious uncontrolled medical disorder that would preclude study participation
• No active infection
• No psychiatric illness that would preclude study compliance
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)

Endocrine therapy:

• See Disease Characteristics

Radiotherapy:

• At least 3 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• At least 2 weeks since prior major surgery