Inclusion Criteria:

- Histologically or cytologically confirmed small cell lung cancer (SCLC). Mixed
histology will not be eligible.

- Progression of disease after only one prior platinum containing chemotherapy regimen.
Prior Regimen must not have contained irinotecan

- All patients must have measurable disease.

- Patients may have received prior radiation therapy but they must have recovered from
all treatment-related toxicities.

- ECOG performance status 0-1

- Adequate hematologic function

- Adequate liver and renal function

- Ability to swallow oral medication

Exclusion Criteria:

- Patients with more than one prior regimen of chemotherapy or prior regimen that did
not contain a platinum agent. Note: Patient who stopped prior therapy due to
toxicity or had less than 2 cycles of platinum based therapy would not be eligible
for the phase II portion of this study.

- Prior chemotherapy regimen containing irinotecan.

- Active secondary malignancy.

- Unstable or progressive brain metastases.

- Prior history of radiation therapy to > 25% of the bone marrow.

- Uncontrolled concurrent illness including, but not limited to: serious uncontrolled
infection, symptomatic congestive heart failure (CHF), unstable angina pectoris,
cardiac arrhythmia, or psychiatric illness/social situations that would limit
compliance with the study requirements.

- Failure to recover from toxicities related to prior therapy (e.g., surgery,
radiation, chemotherapy).