2256P - The microenvironment of normal mucosa could predict recurrence in the stage II/III colorectal cancer: Multicenter, multiomics study

Background

In this study, we aimed to investigate the microenvironment of normal mucosa to predict prognosis of stage II/III colorectal cancer (CRC), after surgery.

Methods

We divide the groups using transcriptome sequencing data of prospectively collected tumors and paired normal tissue, obtained from the margins of the resected specimens from 111 patients at Samsung medical center. Groups were defined as follows: tumor-like microenvironment in normal mucosa group (tNME): high tumor signature in normal mucosa; normal microenvironment group (NME): low tumor signature in normal mucosa. The impact of this classification was further evaluated in two independent cohorts (Korean multi-center cohort and TCGA cohort). The microbial, and biological differences between groups were investigated based on 16s rRNA metagenomics and single-cell RNA sequencing.

Results

A total of 38 (34%) were classified as tNME. There were no significant differences in age, sex, TNM stage and CMS between subgroups. With a median follow-up of 57.9 months, tNME showed poorer 3-year recurrence-free survival (RFS) (56.0 % vs. 78.9 %, P=0.008) and 3-year overall survival (OS) (79.0 %vs. 87.7%, P=0.095) compared to NME. These were validated in the Korean multi-center validation cohort (3-year RFS: 55.3% vs. 74.5%, P=0.045), and TCGA cohort (3-year OS: 62.2% vs. 91.7%, P=0.071). Metagenomics exhibited a significantly lower proportion of carcinogenic genus including Fusobacterium, Bacteroides in normal of NME. There were significant differences in beta diversity between tumor and normal in NME, while no significant differences were noted in tNME, which suggests the feature of bacterial biofilm. PathSeq-based computational method of single-cell RNA sequencing revealed more proportion of infected cancer cells in tNME. EMP1 +epithelial cells were correlated with recurrence, and more proportion of this cluster, along with GZMK high CD8 T cells, inflammatory cancer-associated fibroblasts were noted in tumor of tNME, while more proportion of neutrophil was noted in normal of tNME.

Conclusions

The microenvironment of normal mucosa status could be a prognostic biomarker for CRC. The bacterial biofilm with weak intestinal barrier were related to tNME.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Bio & Medical Technology Development Program of the National Research Foundation funded by the Ministry of Science & ICT (grant no. NRF2017M3A9A7050803.

Disclosure

All authors have declared no conflicts of interest.