RecruitingPhase 3Drug trialPhase 3 Trial of Tarlatamab (SC vs IV) in Extensive-Stage Small Cell Lung Cancer After Platinum Based First-line Chemotherapy (ES-SCLC)The primary objective of this study is to demonstrate non-inferiority in pharmacokinetic (PK) parameters of subcutaneous (SC) vs intravenous (IV) tarlatamab administration and to characterize the efficacy, safety, and tolerability of SC tarlatamab in participants with relapsed extensive-stage small-cell lung cancer (ES-SCLC) after platinum-based chemotherapy.