RecruitingPhase 2Drug trialTarlatamab in Advanced Delta-like 3 (DLL3)-Expressing Tumors Including Neuroendocrine NeoplasmsThis study is being done to learn more about the drug tarlatamab in people with your condition. The purpose of this study is to see the efficacy (how well something works) of study treatment (tarlatamab) and whether it causes any side effects. Tarlatamab is being developed as an anti-cancer drug for tumors and is FDA-approved for extensive-stage small cell lung cancer. Tarlatamab is investigational for the purpose of this study.