Observational Study to Evaluate the Safety and Efficacy of Zepzelca™ Injection

Inclusion Criteria: * Patients who voluntarily provide written consent for personal information collection and utilization after receiving an explanation about the objective and methods of the study * Patients who have received or are scheduled to receive Zepzelca™ inj., according to domestic approval indications * Patients with metastatic SCLC who have failed first-line platinum-based chemotherapy Exclusion Criteria: * Patients with no prior history of platinum-based anticancer chemotherapy for cancer treatment * Patients with a history of hypersensitivity reactions to this drug or its components * Pregnant, potentially pregnant, or lactating women * Patients currently participating in another clinical trial (drug or medical device) or planning to participate in another clinical trial during the study period (except for non-interventional clinical studies or cases where the clinical trial drug administration has ended and only follow-up is remaining) * Patients who are judged by the principle Investigator or sub-Investigator to be ineligible to participate in the study.