DISEASE CHARACTERISTICS:

• Histologically confirmed malignancy

  • Metastatic or unresectable
  • No effective standard curative or palliative measures exist
• No known CNS or brain metastasis

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-1

Life expectancy:

• Not specified

Hematopoietic:

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

Hepatic:

• Bilirubin normal
• SGOT/SGPT normal

Renal:

• Creatinine normal
• Creatinine clearance at least 60 mL/min

Cardiovascular:

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia
• No uncontrolled ventricular arrhythmia
• No myocardial infarction within the past 3 months
• No superior vena cava syndrome

Neurologic:

• No grade 1 or greater peripheral neuropathy
• No uncontrolled major seizure disorder
• No spinal cord compression

Other:

• No active serious infection requiring IV antibiotics
• No concurrent uncontrolled illness
• No concurrent unstable or serious medical condition
• No chronic diarrhea or malabsorption
• No history of allergic reactions to compounds similar in chemical or biological composition to benzoylphenylurea
• No psychiatric illness or social situation that would preclude study compliance
• Not pregnant or nursing
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent immunotherapy
• No concurrent growth factors during first 2 courses of study
• Concurrent epoetin alfa allowed

Chemotherapy:

• At least 28 days since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)
• No other concurrent chemotherapy

Endocrine therapy:

• No concurrent hormonal therapy

Radiotherapy:

• At least 28 days since prior large-field radiotherapy
• Prior palliative radiotherapy for painful bone metastases allowed
• No concurrent radiotherapy, including palliative or whole-brain radiotherapy for CNS disease

Surgery:

• At least 28 days since prior major surgery

Other:

• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent investigational or commercial agents or therapies for the malignancy
• No other concurrent investigational agents
• Concurrent bisphosphonates allowed if bone metastases are not only site of measurable or evaluable disease