A Multinational, Retrospective, Real-World Study: Treatment Patterns in Patients With HER2-Positive Locally Advanced
Do-Youn Oh1, Winnie Yeo2, Jen-Shi Chen3
1Division of Medical Oncology, Seoul National University Hospital, Cancer Research Institute, Seoul National University College of Medicine, Integrated Major in Innovative Medical Science, Seoul National University Graduate School, Seoul, Korea. ohdoyoun@snu.ac.kr.
Purpose:
East Asia has the highest gastric cancer incidence globally [1]. Real-world (rw) treatment patterns and outcomes for HER2-positive (HER2+) advanced gastric or gastroesophageal junction cancer (aGC/GEJC) remain poorly understood.
Materials And Methods:
This study enrolled adults with HER2+ aGC/GEJC diagnosed since January 2016 who received ≥2 lines of therapies (LOTs) with ≥6 months of follow-up across 31 centers in South Korea (KR), China (CN), Taiwan (TW), and Hong Kong (HK). Data were collected through November 2023. Treatment patterns, rw-efficacy outcomes, and adverse events of interest were analyzed descriptively.
Results:
Of 356 eligible patients (KR: 119, CN: 137, TW: 75, HK: 25), chemotherapy plus HER2-targeted monoclonal antibody was the most common 1st LOT regimen (61.0%), although utilization varied across countries/regions. Cross-country/region heterogeneity in treatment patterns emerged from the 2nd LOT onward. Median rw-overall survival varied across countries/regions (KR: 37.1; TW: 13.7; HK: 18.1 months); reliable survival estimation was precluded in CN due to ~50% loss to follow-up. Exploratory analyses suggested no survival benefit with trastuzumab use across multiple versus single LOT(s) (nominal p=0.96); however, sequential use of ≥2 HER2-targeted therapy types with distinct mechanisms of action (MoAs) may be associated with longer survival compared to a single type (nominal p=0.009).
Conclusion:
Cross-country/region heterogeneity in HER2+ aGC/GEJC treatment exists, likely driven by differential drug accessibility. Exploratory analyses suggested possible associations between HER2-targeted therapy and improved outcomes; however, inherent biases preclude causal inference. The sequential use of HER2-targeted therapies with distinct MoAs may be associated with clinical benefit, requiring prospective validation (NCT05606094).
