Abstract 4628: Exploring the differences in immunotherapy efficacy and immune microenvironment characteristics among colorectal cancer patients with different notch receptor gene subtypes

Abstract Background: The NOTCH signaling pathway is a highly conserved signaling system regulated by close-range cell-to-cell interactions. The interaction between NOTCH receptors (NOTCH1-4) and "classical" ligands, or the activation of other non-classical pathways, is associated with the occurrence and progression of various tumors. Although some studies have confirmed a correlation between the efficacy of immunotherapy and NOTCH gene mutations, no definitive conclusion has been reached in colorectal cancer. Exploring the tumor immune microenvironment may help us find better answers. Methods: An independent cohort (MSKCC) comprising next-generation sequencing (NGS) data from 109 pan-cancer colorectal cancer (CRC) patients on immunotherapy outcomes. Tumor tissue samples from 249 Chinese CRC patients were analyzed using NGS and multiplex immunohistochemistry (mIHC). The mIHC were stained using the Detection Kit (Akoya), targeting 13 markers Results, showing immune cell percentages of total cells, provided insights into cell subpopulation distributions in tumor and stroma. Result: In the MSKCC cohort revealed that CRC patients with NOTCH3 mutations had significantly longer overall survival (OS) following immunotherapy (11.5 m VS 8 m; P = 0.008). In contrast, although patients with mutations in other NOTCH pathway genes showed numerically longer OS compared to the wild-type group, the differences were not statistically significant. In Chinese patients, Among the 249 Chinese CRC patients included in the study, 21.7% (54/249) carried NOTCH gene mutations, with mutation rates of 12.0% for NOTCH1, 7.6% for NOTCH2, 11.6% for NOTCH3, and 7.2% for NOTCH4. Further analysis of the immune microenvironment characteristics revealed that patients with NOTCH1 (P=0.002), NOTCH2 (P=0.003), and NOTCH3 (P=0.0192) mutations had significantly higher levels of CD8+ T-cell infiltration in the tumor parenchyma compared to the wild-type, while no significant differences were observed for the other mutations. An additional analysis of differences between the tumor parenchyma and stroma showed that the percentage of CD8+ T cells in the tumor stroma was significantly higher than in the parenchyma for patients with NOTCH3 mutations (P=0.0307), whereas no significant differences were observed for the other three mutation subtypes. Similarly, patients with NOTCH3 (P=0.0446) and NOTCH4 (P=0.0285) mutations exhibited significantly higher levels of NK cell infiltration in the tumor parenchyma compared to the stroma. Conclusions: NOTCH pathway genes have a better immune microenvironment, which may be the reason for the better immune efficacy of patients with Notch pathway mutations. In particular, NOTCH3 has more CD8+ T cell reserves in stroma and more NK into the tumor parenchyma, which shows significantly better immune efficacy. Citation Format: Junyi Chen, Jiahui Fang. Exploring the differences in immunotherapy efficacy and immune microenvironment characteristics among colorectal cancer patients with different notch receptor gene subtypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4628.