This is a Phase II, open-label, multicenter, single-arm, exploratory "proof of concept" study. Diflomotecan (7 mg fixed dose) will be administered as a 20-minute IV infusion once every 3 weeks in patients with sensitive small cell lung cancer (SCLC) with progressive disease after first-line treatment with a platinum-based regimen.
Main Inclusion Criteria: * Documented small cell lung cancer (SCLC) * Measurable disease * One line of previous chemotherapy, including any platinum analogue, and excluding any camptothecin analogues, with objective response and relapsed no less than 3 months Main Exclusion Criteria: * Uncontrollable brain metastasis * Treated with an investigational drug within 30 days