RecruitingPhase 2Drug trialEfficacy and Safety Evaluation of Tarlatamab in Advanced Extrapulmonary Neuroendocrine Carcinoma PatientsThis is a phase 2 single-arm, open-label clinical trial designed to evaluate the efficacy and safety of tarlatamab in patients with relapsed extrapulmonary neuroendocrine carcinoma (EPNEC) who have previously received platinum-based first-line chemotherapy. Participants will receive tarlatamab on Cycle 1 Day 1 (C1D1), Day 8 (C1D8), and Day 15 (C1D15), followed by administration every two weeks thereafter. No placebo control is included in this study.