Inclusion Criteria

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