Sirolimus in Treating Patients With Metastatic or Unresectable Solid Tumors

DISEASE CHARACTERISTICS: * Histologically confirmed solid tumor malignancy * Metastatic or inoperable disease * Failed curative or standard palliative therapy OR no such therapy exists * Evaluable or measurable disease * Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan * Tumor amenable to serial biopsies * No known brain metastases PATIENT CHARACTERISTICS: * ECOG 0-1 * Life expectancy ≥ 3 months * WBC \> 3,500/mm³ * Absolute neutrophil count \> 1,500/mm³ * Hemoglobin \> 9 g/dL * Creatinine ≤ 2.0 mg/dL * Bilirubin ≤ 2 mg/dL * ALT and AST ≤ 5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 5 times ULN * Triglycerides \< 2 times ULN * Total cholesterol \< 2 times ULN * Willing to undergo serial tumor biopsies and normal skin biopsies * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No immunodeficiency * No gastrointestinal tract disease resulting in an inability to take oral medication * No requirement for IV alimentation * No active peptic ulcer disease * No active infections * No other uncontrolled medical conditions that could potentially increase the risk of toxicities or complications of this therapy * No concurrent or second malignancy within the past 5 years * No clinically significant cardiovascular disease, including any of the following: * Myocardial infarction within the past 12 months * Unstable angina * Peripheral vascular disease ≥ grade 2 * Uncontrolled congestive heart failure * Uncontrolled hypertension (i.e., systolic blood pressure \[BP\] \> 170 mm Hg, diastolic BP \> 95 mm Hg) PRIOR CONCURRENT THERAPY: * Recovered from prior anticancer therapy * No unresolved chronic toxicity \> CTC grade 2 * No prior surgical procedures affecting absorption * More than 4 weeks since prior surgery except minor procedures (e.g., dental work or skin biopsy) * More than 1 month since prior participation in an investigational drug trial * More than 1 month since prior chemotherapy * No concurrent use of any of the following: * Phenytoin * Carbamazepine * Barbiturates * Rifampin * Phenobarbital * Cyclosporine * Clarithromycin * Diltiazen * Clotrimazole * Ketoconazole * Fluconazole * Hypericum perforatum (St. John's wort) * Cimetidine * Grapefruit juice * No concurrent immunosuppressants * No other concurrent investigational or commercial agents or therapies for this malignancy