Imatinib Mesylate, Gemcitabine, and Capecitabine in Treating Patients With Advanced Solid Tumors

Inclusion Criteria: * Histologically confirmed solid tumor, meeting 1 of the following criteria: * Failed standard therapy and subsequent line therapy * Disease for which no standard therapy exists * Any number of prior therapies are allowed provided standard treatment options have either been exhausted or are unable to be administered, in the opinion of the treating physician * Measurable or nonmeasurable disease * Measurable disease is defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by CT scan or ≥ 10 mm by spiral CT scan * Nonmeasurable disease is defined as all other lesions, including small lesions (\< 20 mm by conventional techniques or \< 10 mm by spiral CT scan) and truly nonmeasurable lesions, including the following: 1. Leptomeningeal disease 2. Bone lesions 3. Ascites 4. Pleural or pericardial effusion 5. Lymphangitis cutis/pulmonis 6. Abdominal masses that are not confirmed and followed by imaging techniques 7. Cystic lesions * Brain metastases allowed provided both of the following are true: * Patient has undergone resection and/or radiotherapy and does not require steroids * No evidence of disease progression by CT scan or MRI at least 4 weeks after completion of steroids, surgery, and/or radiotherapy * ECOG performance status 0-2 * Absolute neutrophil count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Hemoglobin ≥ 8.5 g/dL (epoetin alfa supplementation allowed) * Bilirubin ≤ 1.5 times upper limit of normal (ULN) (except if due to Gilbert's syndrome) * AST and ALT ≤ 2.5 times ULN * Creatinine \< 1.5 times ULN * Fertile patients must use effective barrier method contraception during and for 3 months after completion of study treatment * Must be able to tolerate oral intake for the administration of imatinib mesylate and capecitabine * Prior treatment with gemcitabine hydrochloride, capecitabine, or imatinib mesylate allowed provided all three drugs were not used in combination simultaneously * Prior radiotherapy allowed provided the lesion treated is not used to assess response and has not demonstrated progression after treatment * At least 2 weeks since prior radiotherapy * More than 2 weeks since prior major surgery * At least 4 weeks since prior systemic therapy (6 weeks for nitrosoureas) and recovered * More than 4 weeks since prior packed red blood cell transfusions * Concurrent bisphosphonate therapy allowed for skeletal metastases provided therapy is started before study entry Exclusion Criteria: * Not pregnant or nursing/negative pregnancy test * No active serious infections * No known allergy or hypersensitivity to study drugs or their formulation * No comorbidity or condition which would preclude study participation * No other primary malignancy within the past 5 years except basal cell skin cancer, cervical carcinoma in situ, or another primary malignancy that is not currently clinically significant or requires active intervention * No prior radiotherapy to ≥ 25% of the bone marrow * No concurrent anticoagulation therapy with warfarin * Therapeutic anticoagulation with low-molecular weight heparin or heparin allowed * Mini-dose warfarin (e.g., 1 mg/day) for prophylaxis of central venous catheter thrombosis allowed at the discretion of the treating physician * No other concurrent anticancer agents, including chemotherapy and biologic agents * No other concurrent investigational drugs * No concurrent routine systemic corticosteroid therapy (corticosteroid therapy may only be administered after consultation with the principal investigator) * No other malignant disease * No New York Heart Association class III-IV cardiac disease * No congestive heart failure * No myocardial infarction within the past 6 months * No known chronic liver disease (e.g., chronic active hepatitis or cirrhosis) * No known HIV infection * No prior radiotherapy to ≥ 25% of the bone marrow * No concurrent anticoagulation therapy with warfarin * Therapeutic anticoagulation with low-molecular weight heparin or heparin allowed * Mini-dose warfarin (e.g., 1 mg/day) for prophylaxis of central venous catheter thrombosis allowed at the discretion of the treating physician * No other concurrent anticancer agents, including chemotherapy and biologic agents * No other concurrent investigational drugs * No concurrent routine systemic corticosteroid therapy (corticosteroid therapy may only be administered after consultation with the principal investigator)