DNA damage and repair gene panel as a biomarker of immune checkpoint inhibitor response.

Abstract

e15052 Background: Immune checkpoint inhibitors (ICIs) have become the standard of care in various cancers, although predictive biomarkers for efficacy still remain largely unknown. Methods: This study aims to develop a novel gene panel by selecting DNA damage and repair (DDR) genes from the Catalogue of Somatic Mutations in Cancer (COSMIC) database and perform validation using publicly available cohorts. Association between the DDR gene panel and tumor mutation burden or microsatellite status were analyzed from The Cancer Genome Atlas (TCGA) database. To further improve the clinical accessibility of the DDR gene panel, we analyzed the feasibility of its predictive value using cell free DNA in from 64 patients receiving ICIs. Results: The 193 mutated DDR genes in various cancers were chosen from the COSMIC databank, and the DDR genes found to individually predict a response rate > 50% in publicly melanoma cohort (Van Allen, et al) were selected. Eighteen DDR genes were selected as the DDR gene panel. The prevalence of the DDR gene mutations and predicted response rate of ICIs were validated in other three publicly available cohorts (Hugo et al, Synder et al, and Rizvi et al.). Tumor mutational burden and high microsatellite instability were positively associated with mutations of the 18 DDR genes for most cancers. Further validation was performed using cell-free DNA from cancer patients receiving ICIs. This DDR gene panel was detected in approximately 30% of various cancers, achieving a predicted response rate of approximately 60% in patients receiving ICIs. Conclusions: Our developed DDR gene panel can serve as a novel and reliable biomarker that can provide critical information for predicting the response to ICIs in cancer patients and guide the appropriate administration of ICIs in clinical practice.