DISEASE CHARACTERISTICS:

• Histologically confirmed malignancy, including, but not limited to, any of the following:

  • Renal cell carcinoma
  • Melanoma
  • Kaposi's sarcoma
  • Breast, prostate, colorectal, or lung adenocarcinoma
  • Bone and soft tissue sarcomas
  • Lymphoma
  • Myeloma
  • Tumors of neuroendocrine and endothelial cell origin
• Stage IV disease
• Refractory disease, resistant to established treatments, or no effective treatment available
• Measurable or evaluable disease
• CNS metastases allowed if no prior definitive therapy within the past 3 months and no glucocorticoids required

PATIENT CHARACTERISTICS:

• ECOG performance status 0-1
• Granulocyte count > 1,500/mm^3
• Platelet count > 100,000/mm^3
• Creatinine < 1.0 times upper limit of normal (ULN)
• Creatinine clearance ≥ 60 mL/min
• Bilirubin < 1.5 times ULN
• AST/ALT < 1.5 times ULN
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after completion of study treatment

• No history of any of the following:

  • Atrial fibrillation, atrial flutter, or other serious arrhythmia (excluding asymptomatic atrial and ventricular premature complexes)
  • Congestive heart failure currently requiring treatment
  • Angina pectoris
  • Other severe cardiovascular disease (i.e., New York Heart Association class III or IV heart disease)
• No baseline ECG abnormalities suggestive of cardiac conduction delay, i.e., 1° or greater atrio-ventricular block and/or complete or incomplete (QRS > 120 ms) bundle branch block, or repolarization abnormalities (i.e., QTc ≥ 0.48 sec)
• No systemic infections requiring antibiotics within the past 14 days
• No known hepatitis B surface antigen positivity
• Psychologically prepared to participate in study treatment

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 4 weeks since prior interferon (IFN) therapy and/or ≤ 400 million units of IFN
• At least 3 weeks since prior major surgery
• At least 3 weeks since prior radiation therapy or chemotherapy
• No prior solid organ allografts or allogeneic bone marrow transplantation
• No concurrent daily glucocorticoids except for physiological replacement
• No other concurrent medications known to prolong QT interval