Gemcitabine With or Without Imatinib Mesylate in Treating Patients With Metastatic or Unresectable Kidney Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed renal cell carcinoma * Metastatic disease OR unresectable primary tumor * No known curative therapy exists * Documented progressive renal cell carcinoma as defined by RECIST criteria within the past 6 months * Measurable disease with ≥ 1 unidimensionally measurable lesion * No known symptomatic brain metastasis or untreated brain metastases or carcinomatous meningitis * Treated brain metastasis allowed provided the following criteria are met: * Clinically stable * More than 7 days since prior steroids PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Life expectancy ≥ 3 months * Absolute neutrophil count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * AST and ALT ≤ 2.5 times ULN * Creatinine ≤ 1.5 times ULN OR creatinine clearance ≥ 60 mL/min * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective nonhormonal contraception during and for 3 months after completion of study treatment * Must be able to swallow oral medication * No coexisting medical condition that would preclude study compliance * No history of allergic reaction to compounds of similar chemical or biological composition to gemcitabine hydrochloride and/or imatinib mesylate * No uncontrolled illness that would preclude study participation * No symptomatic congestive heart failure * No unstable angina pectoris * No cardiac arrhythmia requiring therapy * No myocardial infarction within the past 6 months * No active infection * No other malignancy within the past 5 years except carcinoma in situ of the cervix or nonmelanoma skin cancer * No New York Heart Association class III-IV congestive heart failure * No known chronic liver disease (i.e., chronic active hepatitis or cirrhosis) * No known HIV positivity * No significant history of noncompliance to medical regimens PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Recovered from all prior therapy * No more than 3 prior treatment regimens, including any of the following: * No more than 1 prior cytotoxic therapy * Immunotherapy regimens comprising interferon and/or aldesleukin * Therapy with molecular targets * Any combination of the above treatments to a maximum of 3 total therapies * No prior gemcitabine hydrochloride for metastatic disease * No prior imatinib mesylate for metastatic disease * More than 2 weeks since prior major surgery * At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) * At least 3 weeks since prior anti-vascular endothelial growth factor therapy * At least 3 weeks since prior radiotherapy * Must have evidence of ≥ 1 measurable target lesion outside the radiation fields OR radiologically confirmed disease progression within the radiation fields after completion of radiotherapy * At least 28 days since prior and no other concurrent investigational or commercial agents, unless disease is rapidly progressing * No concurrent therapeutic warfarin * Concurrent low molecular weight heparin or heparin allowed for therapeutic anticoagulation * Concurrent prophylactic warfarin therapy ≤ 1 mg daily to maintain catheter patency allowed * No concurrent filgrastim (G-CSF) for prevention of neutropenia * No other concurrent chemotherapy, immunotherapy, hormonal cancer therapy, radiation therapy, or cancer surgery * No concurrent routine use (i.e., daily or every other day) of systemic corticosteroid therapy (in supraphysiologic doses) * No concurrent medication that would preclude study compliance