Real-world applications of tumor mutation burden (TMB) analysis using ctDNA and FFPE samples in various cancer types of Turkish population

Abstract

Tumor mutation burden (TMB) has become one of the most popular approaches in the last decade as a molecular genetic testing strategy for cancer therapeutics that represents the somatic variations per Mbase in coding regions of the genome and which can be performed via comprehensive genomic profiling (CGP) by next generation sequencing (NGS). TMB is most commonly used to stratify the patients for immunotherapy as well as the actionable variant detection for possible other therapeutics. In this context, within this study, we share our results of the TMB score distribution of cancer patients together with distinctive diagnoses and specimens. The study was conducted from a total of 278 samples. One hundred seventy six (176) of them were formalin-fixed paraffin-embedded (FFPE) tissue samples and 102 liquid biopsy samples.  Samples were sequenced using a multi-gene NGS panel consisting of 486 cancer-related genes (Illumina-NextSeq500/550). Bioinformatics analyzes were performed using an optimized in-house bioinformatics pipeline. As a result, the studies of 91.7% (n=255) among all samples were successfully performed in which total of 21 different cancer types were included. The lung cancer group was the most frequent (n=43 patients), followed by 31 colorectal cancer and 22 ovarian cancer patients. The classification of TMB scoring was very high (>50), high (20-50), moderate (5-20) and low (<5). The shared data of this study represents a cancer genome atlas-like data set for TMBs of Turkish cancer patients in relation to various cancer types and specimens in comparison with The Cancer Genome Atlas (TCGA) data.