This study will gather information on the effectiveness and safety of a treatment program for small cell lung cancer (SCLC) that uses an FDA approved chemotherapy combination, radiation therapy, and an oral investigational drug that may enhance the effects of radiation therapy. Study patients will receive two additional courses of the standard chemotherapy combination after completing radiation therapy.

Inclusion Criteria:

• Patients must have newly diagnosed, limited stage SCLC (small cell lung cancer), with no prior radiotherapy. Patients are allowed to have had a resection or biopsy.
• Women of reproductive potential must have a negative serum pregnancy test at the study screening visit.
• Patients must give written informed consent to participate in the study.
• Patients must be able to take oral medication.
• Patients should be completely recovered from recent surgery.
• Laboratory criteria: Patients must have adequate bone marrow reserve and adequate kidney and liver function.
• Patients must be evaluated by the radiation oncologist prior to study entry.

Exclusion Criteria:

• Extensive Stage SCLC.
• Women who are pregnant or lactating.
• Use of an investigational drug within 30 days prior to the first dose of study medication.
• Any medically/clinically significant active infection.
• Symptoms of the SCLC spreading to the brain.
• Patients with limited stage SCLC who have undergone complete resection with no measurable disease prior to starting chemotherapy.
• Severe medical problems, unrelated to SCLC, that would limit the patient's full ability to follow all study rules and procedures, or that would expose the patient to extreme risk.
• Other ongoing, immunotherapy or radiotherapy being administered at the time as study participation.