 - Phase II: extensive stage small cell lung cancer with progression or recurrence after exactly one platinum-containing regimen. Patients who progressed during or within one month of completing platinum-based chemotherapy will be excluded. Patients who received primary curative chemoradiation therapy for limited disease, but who recur within the primary tumor site, previously radiated field or with distant metastases are also allowed to participate. Patients who have clinical evidence of recurrent small cell lung cancer do not require a confirmatory biopsy to be eligible for this trial. Prior irinotecan is not allowed. 