Abstract 7726: Expression profile of therapeutic target CDH17 in gastric cancer

Abstract Background: CDH17 has recently gained attention as a promising therapeutic target in gastric cancer (GC), driven by advances in antibody-drug conjugates and other targeted modalities designed to exploit its highly restricted expression in gastrointestinal tissues. Despite growing therapeutic interest, the real-world prevalence and staining characteristics of CDH17 in clinical GC samples are not well established. A clearer understanding of CDH17 expression patterns may help refine patient selection strategies, guide the development of CDH17-directed therapies, and support biomarker-driven clinical decision-making. Methods: Tissue microarrays from 73 patients with histologically confirmed gastric cancer were evaluated by immunohistochemistry (IHC). CDH17 staining was performed using the Celnovte IHC platform with CNT-PolyStacker secondary antibodies (clone C5A5), which enables high-specificity visualization of membrane-associated and cytoplasmic expression. Staining intensity was scored semi-quantitatively, and CDH17 positivity was defined as ≥50% of tumor cells demonstrating 2+ or 3+ intensity. All slides were reviewed independently by board-certified pathologists to ensure consistent interpretation. Results: CDH17 expression was identified in 15.1% (11/73) of gastric cancer cases. Positive tumors demonstrated strong, well-defined membranous and cytoplasmic staining, consistent with the known biology of CDH17 as an intestine-specific adhesion molecule. Within this cohort, CDH17-positive cases appeared across both intestinal and diffuse histologic subtypes, and no clear relationship with tumor differentiation, sample location, or patient demographic factors was observed. The overall expression rate aligns with reported ranges from prior smaller studies, suggesting that CDH17 may define a distinct molecular subset of GC patients potentially suitable for targeted therapeutic approaches. Conclusions: CDH17 expression was detected in approximately 15% of gastric cancer cases in this real-world cohort, reinforcing the relevance of CDH17 as a potential biomarker for targeted therapy development. As CDH17-directed agents continue to advance in early-phase clinical trials, reliable biomarker prevalence data will be essential for refining clinical trial eligibility criteria and informing market-wide testing strategies. Additional studies with larger and more diverse patient populations are warranted to validate the prevalence, biological implications, and potential predictive value of CDH17 expression in gastric cancer. Citation Format: Fei Chu, Jiaxing Zhao, Dan Huang, Hao Luo, Aaron Hong, Ye Tian, Chang Liu, David Chu, Jim Lu. Expression profile of therapeutic target CDH17 in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7726.