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