DISEASE CHARACTERISTICS:

• Histologically confirmed metastatic or unresectable solid tumor that is unlikely to respond to existing therapy or for which no curative therapy exists
• Measurable or evaluable disease which is clearly progressive
• No hematologic malignancies
• No brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-1
• Karnofsky 80-100%

Life expectancy:

• At least 3 months

Hematopoietic:

• WBC greater than 4,000/mm3
• Absolute neutrophil count greater than 1,500/mm3
• Platelet count greater than 100,000/mm3

Hepatic:

• Bilirubin less than 1.5 mg/dL
• SGOT and SGPT less than 2 times normal
• No active (clinical or subclinical) hepatitis B or C infection

Renal:

• Creatinine less than 1.5 mg/dL OR
• Creatinine clearance at least 60 mL/min

Cardiovascular:

• No congestive heart failure
• No symptoms of coronary artery disease
• No serious cardiac arrhythmias
• No evidence of prior myocardial infarction

Other:

• No active infection requiring antibiotic therapy
• No medical condition requiring the use of corticosteroids during study
• No autoimmune or rheumatologic disease
• No seizure disorders
• No significant medical disease that would preclude study
• HIV negative
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 4 weeks since prior immunotherapy and recovered
• At least 6 months since prior interleukin-2
• At least 12 months since prior interleukin-12
• No more than 2 prior biological response modifier treatment regimens

Chemotherapy:

• At least 4 weeks since prior chemotherapy (6 weeks for prior nitrosoureas or mitomycin) and recovered
• No more than 2 prior chemotherapy regimens
• No concurrent chemotherapy

Endocrine therapy:

• At least 4 weeks since prior hormonal therapy and recovered
• No concurrent hormonal therapy (including steroids and hormone replacement therapy)

Radiotherapy:

• At least 4 weeks since prior radiotherapy and recovered
• No concurrent radiotherapy

Surgery:

• No prior organ allografts

Other:

• At least 2 weeks since prior IV antibiotics
• No other concurrent investigational agents