TP53 and CHEK2 germline mutations in malignant solid tumors.

3119 Background: Li-Fraumeni syndrome (LFS, OMIM #151623) is an autosomal dominant cancer predisposition syndrome. Typical LFS tumors comprise adrenocortical carcinomas, sarcoma, breast cancer and central nervous system tumors. LFS is also associated with an increased risk of a multitude of other common types of cancer, such as prostate cancer, lung cancer, gastric cancer, colorectal cancer, ovarian cancer, melanoma, etc. TP53 germline mutations are the most common gene with LFS. Germline mutations of CHEK2 have been identified as another predisposing gene and associated with a range of cancer types. However, the pattern of TP53 and CHEK2 germline mutations in malignant tumors remains unknown. Methods: We identified 8535 malignant solid tumors patients without selecting age or family history in a retrospective cohort. Germline mutations were categorized based on ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity. The patients were divided into three groups, P group (with pathogenic mutations), LP group (with likely-pathogenic mutations) and Non_P group (neither pathogenic nor likely-pathogenic mutation). Statistical significance was defined as P-value less than 0.05. Results: A total of 461 (461/8535) patients carried TP53 or CHEK2 germline mutations were identified, in which 15 patients with pathogenic mutations and 17 patients with likely-pathogenic mutations. One patient with lung cancer in LP group carried TP53 homozygous mutation ( p. Ser215Ile), and the remaining 31 patients all carried heterozygous mutations. Among these 31 carriers, 16 (51.6%) carried nonsense or missense mutations (10 for nonsense and 6 for missense mutations). 3 patients in the P group carried CHEK2 p. Y139* (one liver cancer patient and two lung cancer patients) were identified. The median age of group P, LP and Non_P was 55 (39 for TP53, 61 for CHEK2), 63 (52 for TP53, 66 for CHEK2) and 59, respectively. Somatic mutation analysis found no significant difference in tumor mutation burden (TMB) among three groups. The SNV/INDEL mutation frequency of LRP1B in the P or LP group was significantly lower than the Non_P group. Conclusions: Our data showed that 0.375% (32/8535) malignant solid tumor patients carried TP53 (16/8535) or CHEK2 (16/8535) germline pathogenic or likely-pathogenic mutations. The relationship between germline mutations and cancer susceptibility will be studied in the future.[Table: see text]