Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed small cell lung cancer (SCLC)

- Limited or extensive stage disease

- Progressive or recurrent disease after an initial response to first-line treatment
with a platinum-based chemotherapy with or without concurrent definitive radiotherapy
to the chest

- Chemotherapy must have been completed at least 90 days prior to documentation of
relapse

- Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by
conventional techniques OR ≥ 10 mm by spiral CT scan

- Lesions that are not considered measurable include the following:

- Bone lesions

- Leptomeningeal disease

- Ascites

- Pleural or pericardial effusion

- Abdominal masses that are not confirmed and followed by imaging techniques

- Cystic lesions

- Tumor lesions situated in a previously irradiated area, unless progression
after radiotherapy is documented in these lesions

- No known brain metastases

- Previously treated brain metastases allowed provided they are neurologically
stable for ≥ 4 weeks

PATIENT CHARACTERISTICS:

- ECOG performance status 0-1

- Platelet count ≥ 100,000/mm^3

- WBC ≥ 1,500/mm^3

- Bilirubin ≤ 1.5 times upper limit of normal (ULN)

- Creatinine ≤ 1.5 times ULN OR creatinine clearance ≥ 60 mL/min

- AST ≤ 2.5 times ULN

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception during and for ≥ 6 weeks after
completion of study therapy

- No significant cardiac disease, including any of the following:

- New York Heart Association class III-IV heart disease

- Myocardial infarction or ventricular tachyarrhythmia within the past 6 months

- Prolonged QTc > 480 msec (Fridericia correction)

- Major conduction abnormality (unless a cardiac pacemaker is present)

PRIOR CONCURRENT THERAPY:

- No more than 1 prior chemotherapy regimen

- No prior dasatinib or compounds of similar chemical composition or similar biologic
therapeutic activity including, but not limited to, any inhibitors of SRC, BCR-ABL,
c-KIT, EPHA2, or PDGFRβ kinases

- At least 2 weeks since prior definitive or palliative radiotherapy

- Prior radiotherapy allowed in the context of combined modality treatment with
curative intent for limited stage disease; prophylactic cranial radiotherapy; or
palliative radiotherapy initially or at relapse

- At least 2 weeks since prior surgery and recovered

- At least 1 week since prior and no concurrent agents with proarrhythmic potential

- At least 1 week since prior and no concurrent CYP3A4 inhibitors or inducers

- At least 1 week since prior and no concurrent grapefruit concentrate

- No concurrent palliative radiotherapy

- No concurrent hormones or other chemotherapeutic agents, except steroids for adrenal
failure, hormones for noncancer-related conditions (e.g., insulin for diabetes), or
intermittent dexamethasone as an antiemetic

- No concurrent combination antiretroviral therapy for HIV-positive patients

- No other concurrent chemotherapeutic or investigational agents