Abstract LB109: Detection of high grade intraepithelial neoplasia in colorectal cancer using a new blood-based multiplex septin9 methylation assay

Abstract Colorectal cancer (CRC) is the third most common cancer worldwide, and regular screening is effective in reducing its mortality. Epi proColon was the first blood-based Septin9 gene methylation assay approved by the US FDA for CRC screening. However, the broader application of this assay has been hindered by its relatively lower sensitivity in detecting early-stage CRC and precancerous lesions. In this study, we developed a new multiplex Septin9 methylation assay, named ColonUSK, which simultaneously detects two CpG-rich subregions in the promoter of the Septin9 gene and an internal control in a single reaction. In comparison with the Sepin9 assay targeting only one CpG-rich subregion, this new assay demonstrated improved sensitivity, with a detection limit as low as 12pg of the positive DNA. To assess its value in CRC screening, we conducted an opportunistic screening study involving a total of 1366 subjects. Blind testing was performed to evaluate ColonUSK in comparison with clinical diagnosis using colonoscopy and pathological examination (the clinical gold standard). The clinical sensitivities of ColonUSK for detecting CRC and advanced adenoma were 77. 34% (95% CI: 72. 89%-81. 26%) and 25. 26% (95% CI: 17. 16%-35. 41%), respectively. The clinical specificity of the assay for non-CRC cases was 95. 95% (95% CI: 94. 36%-97. 13%). Notably, ColonUSK was able to detect 54. 29% of cases with high-grade intraepithelial neoplasia. The Kappa test value for this experiment was 0. 76, indicating a high degree of consistency between ColonUSK and pathological diagnosis. Our results suggest that ColonUSK holds potential as a non-invasive screening tool for colorectal cancer. Citation Format: Youming Wu, Yongqin Tong Tong, Haitao Zhang, Yun Li, Ming Li, Lili Qiu, Wenlan Liu, Siqing Mei, Yu Mao, Yanhua Cao, Caiyan Su, Wentao Yu, Junli Wang, Taizhong Wang, Zhongyuan Zhu, Dehua Derek Yu. Detection of high grade intraepithelial neoplasia in colorectal cancer using a new blood-based multiplex septin9 methylation assay abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr LB109.