Effectiveness and Safety of Trastuzumab Deruxtecan in Chinese Patients with HER2-Mutant Metastatic Non-Small Cell Lung Cancer (RERUN): Study Protocol for a Real-World, Multicenter, Prospective, Observational Study.

INTRODUCTION: Trastuzumab deruxtecan (T-DXd) is a human epidermal growth factor receptor 2 (HER2)-targeting antibody-drug conjugate that has demonstrated encouraging efficacy and a manageable safety profile in the second-line or later setting for non-small cell lung cancer (NSCLC) harboring HER2 mutations. While T-DXd was approved for treating patients with locally advanced or metastatic HER2-mutant NSCLC in China, real-world data on its use in Chinese clinical practice are lacking. This study will collect real-world data on T-DXd to evaluate its effectiveness and safety in Chinese patients with HER2-mutant metastatic NSCLC, thereby providing additional evidence to the oncology community in China. METHODS: RERUN is a prospective, multicenter, observational cohort study conducted at approximately 30 sites in China. Approximately 150 adult patients (≥ 18 years) with pathologically documented unresectable and/or metastatic non-squamous NSCLC harboring any known activating HER2 mutation are currently being enrolled. The follow-up period will last approximately 6 months after the last patient is enrolled, when sufficient progression-free survival (PFS) maturity (approximately 60% of patients with events) is expected to be reached. All data will be prospectively collected and analyzed descriptively. PLANNED OUTCOMES: The primary outcome is real-world PFS assessed by investigators in patients receiving T-DXd as second-line or later therapy. Secondary outcomes include the time to treatment discontinuation or death, best overall response rate, overall survival, and safety and tolerability. This study will support treatment decision-making in routine oncology practice and improve outcomes for Chinese patients with HER2-mutant NSCLC across diverse healthcare settings. TRIAL REGISTRATION: Study registration number NCT06809764.