DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed small cell lung cancer

  • Recurrent disease after 1 prior platinum-based chemotherapy regimen
• Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan
• No known brain metastases

PATIENT CHARACTERISTICS:

Performance status

• ECOG 0-2 OR
• Karnofsky 50-100%

Life expectancy

• More than 12 weeks

Hematopoietic

• WBC ≥ 3,000/mm^3
• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• Hemoglobin ≥ 8 g/dL

Hepatic

• Bilirubin normal
• AST and ALT ≤ 2.5 times upper limit of normal

Renal

• Creatinine normal OR
• Creatinine clearance ≥ 60 mL/min
• No proteinuria > +1 on 2 consecutive dipsticks taken no less than 1 week apart

Cardiovascular

• QTc ≤ 470 msec by EKG (with Bazett's correction)
• No history of familial long QT syndrome
• No uncontrolled hypertension
• No symptomatic congestive heart failure
• No unstable angina pectoris
• No uncontrolled cardiac arrhythmia

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective double barrier-method contraception ≥ 1 week before, during, and ≥ 2 weeks after completion of study treatment
• Able to take oral medications on a regular basis
• No other uncontrolled illness
• No active or ongoing infection
• No psychiatric illness or social situation that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Chemotherapy

• See Disease Characteristics
• More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)
• No more than 1 prior chemotherapy regimen

Radiotherapy

• More than 4 weeks since prior radiotherapy

Surgery

• More than 4 weeks since prior major surgery

Other

• Recovered from prior therapy
• More than 30 days since prior participation in an investigational trial
• No other concurrent investigational agents
• No other concurrent anticancer therapy
• No concurrent medication that may markedly affect renal function (e.g., vancomycin, amphotericin, pentamidine)
• No concurrent combination antiretroviral therapy for HIV-positive patients