KMT2C as a positive predictor for treatment of immune checkpoint inhibitor and correlation with immune infiltrates in colorectal cancer (CRC).

Abstract

3538 Background: Lysine Methyltransferase 2C (KMT2C), a member of the myeloid/lymphoid or mixed-lineage leukemia (MLL) family, possesses histone methylation activity and is involved in transcriptional co-activation. Present study has shown that KMT2C is positive correlated with better efficacy of Immune checkpoint inhibitor (ICI) in NSCLC. However, the role of KMT2C in treatment of ICI on colorectal cancer (CRC) is still unknown. Methods: NGS (Next Generation Sequencing) was performed on 1628 CRC patients. TMB of these patients were analyzed. A public accessible cohort (Samstein2018) with data from 130 CRC patients were used to investigate the correlation between KMT2C mutation and efficacy of ICI. WES and survival data of TCGA database (1099 CRC) was used to analyze prognostic effect of KMT2C mutation. Furthermore, CIBERSORT was used to analyze the tumor-infiltrating immune cells present in COAD（colon adenocarcinoma, 404 patients）from TCGA database. Results: Among 1628 CRC patient, 230(14.1%) had KMT2C mutation. TMB was positive correlated with KMT2C mutation (Mut vs. WT, 30.75 vs. 7.26 mut/Mb, p < 0.0001). The Samstein2018 cohort showed that KMT2C mutations (15.4%, 20/130) were significantly associated with better OS (Mut vs. WT, 11.5 vs. 7.5 month, HR = 0.29; 95% CI, 0.1-0.81; P = 0.012), and a higher TMB was also observed in KMT2C-Mut group (p = 1.98e-08). In TCGA, no association between KMT2C mutation and OS was observed (P = 0.23), suggesting that was not prognostic factor. Moreover, we analyzed the relationship between KMT2C mutation and immune cell infiltration through CRC TCGA database. The results showed, in COAD, KMT2C mutation was positively correlated with the abundance of CD8+ T cells (P = 0.0014), B cells (P = 0.014), M1 macrophages (P = 0.015), neutrophil (P = 0.0019) and NK cells (P = 0.043), and negatively correlated with Treg cells (p = 0.0063). Conclusions: KMT2C has an impact on the immune microenvironment and may be used as a potential positive predictor for treatment of ICI on CRC patients. The role of KMT2C in immunotherapy warrant further studies.