Gemcitabine and Imatinib Mesylate in Treating Patients With Recurrent or Metastatic Non-Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed non-small cell cancer * Recurrent disease after adjuvant treatment OR progressive disease after 1 prior treatment for recurrent or metastatic disease * Received at least 1 prior chemotherapy regimen and meets the following criteria: * No more than 1 prior chemotherapeutic regimen in the recurrent or metastatic setting * Patients who received prior chemotherapy in the adjuvant setting are eligible when 1 of the following criteria is met: * In first recurrence (after 1 prior regimen) * Received first-line chemotherapy in the recurrent setting after 2 prior regimens * Measurable disease * Must have ≥ 1 measurable target lesion outside prior radiotherapy field OR radiologic confirmation of disease progression within a prior radiotherapy field * No known or untreated brain metastases or carcinomatous meningitis * Clinically stable, treated brain metastases allowed provided it has been \> 7 days since prior steroids PATIENT CHARACTERISTICS: * ECOG performance status 0-1 * 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 contraception during and for 3 months after completion of study treatment * Able to swallow oral medication * No concurrent medical condition that would preclude study compliance * No history of allergic reaction to compounds of similar chemical or biological composition to gemcitabine hydrochloride or imatinib mesylate * No uncontrolled illness that would preclude study compliance, including any of the following: * Symptomatic congestive heart failure * Unstable angina pectoris * Cardiac arrhythmia requiring therapy * Myocardial infarction within the past 6 months * Active infection * No New York Heart Association class III-IV congestive heart failure * No chronic liver disease (i.e., chronic active hepatitis, cirrhosis) * No HIV positivity * No other primary malignancies within the past 5 years, except carcinoma in situ of the cervix or nonmelanoma skin cancer PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) * At least 3 weeks since prior anti-vascular endothelial growth factor therapy and recovered * At least 3 weeks since prior radiotherapy and recovered * More than 28 days since prior and no other concurrent investigational or commercial agents * More than 2 weeks since prior major surgery * No prior gemcitabine hydrochloride or imatinib mesylate for metastatic disease * No prior tyrosine kinase inhibitor, except for gefitinib or erlotinib hydrochloride * No concurrent therapeutic warfarin (prophylactic warfarin therapy ≤ 1 mg daily allowed) * No other concurrent medications that would preclude study compliance * No concurrent chronic systemic corticosteroids