Immune signature as a potential marker for predicting response to immunotherapy in obesity-associated colorectal cancer

Background and Aim It remains unclear whether immunotherapy, which is not generally considered for microsatellite stable (MSS) colorectal cancer (CRC), can be used to effectively treat select CRC patients. We investigated the feasibility of obesity-associated MSS CRC patients for immunotherapy based on genomic alterations. Methods We evaluated differences in genomic alteration types and immune signatures between obese and non-obese patients with MSS CRC. We performed genomic analyses using 434 CRC patients from The Cancer Genome Atlas (TCGA). Patients with MSS CRC were stratified into subgroups based on their BMI and numbers of nonsynonymous single nucleotide variants (nsSNVs) and frameshift insertions and deletions (fs INDELs) using machine learning. Results The obese subgroup showed higher incidences of single nucleotide variants (SNV) and insertions and deletions (INDELs) in comparison with healthy weight patients with MSS CRC. The subgroup, who had higher numbers of nsSNVs and fs INDLEs, exhibited increased immune signatures, increased number of SNV-derived neoantigens, and had up-regulated two immune checkpoint genes in comparison with healthy weight patients with MSS CRC, reflecting interactions between the cancer genome and immune system. Conclusions This study suggests that immunotherapy may be suitable for some obesity-associated CRC patients.