INTRODUCTION: Tarlatamab demonstrated a durable response and promising survival outcomes in patients with previously treated small cell lung cancer (SCLC) in the phase 2, open-label DeLLphi-301 trial. Patient-reported outcomes (PROs) were evaluated to assess the benefit-risk profile of tarlatamab. METHODS: Patients received tarlatamab intravenously every 2 weeks at a dose of 10 mg (regulatory approved dose) or 100-mg until progression or loss of benefit. PROs, including European Organization for Research and Treatment of Cancer 30-item Quality of Life Questionnaire (EORTC-QLQ-C30) and 13-item lung cancer module (LC13), Patient-Reported Outcomes Version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), and the GP5 question of the Functional Assessment of Cancer Therapy - General Form (FACT-GP5), were collected at Cycle 1 (days 1, 8, 22), Cycle 2 (days 1, 15) and every 6 weeks from Cycle 3 onwards. PROs were summarized descriptively alongside the amount and reason for missing data and analyzed using a mixed model for repeated measures. In addition, median time to deterioration (TTD) for symptom and functional scales was analyzed. RESULTS: A total of 100 patients were PRO-evaluable at the selected target dose (10 mg). EORTC-QLQ-C30 and LC13 completion rates (proportion of PRO assessments expected to be completed) were high (>
80%) throughout the study. Least square mean changes from baseline showed a trend towards improvement for the QLQ-C30 subscale of global health status and stabilization for physical functioning. Patients experienced reduced symptom burden for dyspnea which was more pronounced for patients at later cycles (≥ 10 points), and stabilization for chest pain and cough. Median TTD exceeded 6 months for cough and dyspnea and was not estimable for chest pain. Overall, tarlatamab was well tolerated with the majority of patients reporting no bother or a little bit of bother from side effects post baseline. Patient-reported adverse events were generally of mild to moderate severity occurring rarely or occasionally. CONCLUSION: Alongside previously reported antitumor activity, tarlatamab demonstrated a positive benefit-risk profile in previously treated SCLC with favorable PROs across a range of functional outcomes and symptoms, while showing manageable and sustained tolerability. GOV NUMBER: NCT05060026.