Clinical significance of DNA damage response mutations in stage I and stage IIIa NSCLC

DNA damage response (DDR) pathways are essential to sustain genomic stability and play a critical role in cancer development and progression. Here, we investigated the profile of DDR gene mutations in early-stage non-small cell lung cancer (NSCLC) and their prognostic values.

We first examined 74 DDR genes involved in seven DDR pathways and then focused on six specific genes: ATM, BRCA1, BRCA2, CHEK1, BARD1, and BRIP1. A total of 179 stage I and IIIa NSCLC patients who received curative resection in Peking Union Medical College Hospital and their corresponding samples were collected for DNA sequencing, immunohistochemistry and survival analysis.

A total of 167 eligible patients were finally analyzed. Mutation frequencies were 82% and 26.3% for the selected 74 genes and six genes, respectively. Mismatch repair (MMR) and nucleotide excision repair (NER) alterations were observed more frequently in lung squamous cell carcinoma (LUSC) and smokers were more likely to develop the selected six DDR gene mutations than those who never smoked. Deleterious mutations in the six genes were independent prognostic indicators of significantly longer disease-free survival and overall survival. No association was found between DDR gene status and PD-L1 expression, CD8 positive lymphocyte and tumor-associated macrophage infiltration in tumor area. However, numbers of mutations were significantly increased among patients with DDR alterations.

Deleterious mutations of these six genes were common in resected NSCLC and could serve as prognostic biomarkers.