The approval of tarlatamab, the first-in-class delta-like ligand 3 (DLL3)-targeted TCE for extensive-stage small cell lung cancer (ES-SCLC), underscores the importance of sharing early clinical experience with this agent, particularly given its unique safety profile, specific monitoring requirements, and use in a population that often has multiple comorbidities. This evidence concerns the gene DLL3 and small cell lung carcinoma.