Targeted Genomic Sequencing Reveals Novel TP53 In-frame Deletion Mutations Leading to p53 Overexpression in High-grade Serous Tubo-ovarian Carcinoma.

Abstract

High-grade serous carcinoma (HGSC) is the most common histological subtype of ovarian carcinoma. Somatic mutation of tumor protein 53 (TP53) is a hallmark of tubo-ovarian HGSC and is observed in almost all such cases. Highly sensitive targeted genomic sequencing can be used to identify novel mutations that may become potential druggable targets and aid in therapeutic decisions. The aim of this study was to describe the clinicopathological and molecular characteristics of HGSCs with novel somatic TP53 mutations identified by next-generation sequencing (NGS). A commercial NGS panel comprising 170 genes, including TP53, was used to analyze the genetic profiles of 132 ovarian carcinoma cases. The clinicopathological characteristics and p53 immunostaining results of two HGSCs exhibiting novel TP53 mutations were investigated. Eighty-eight (66.7%) out of 132 ovarian carcinoma cases were diagnosed as HGSC. Novel TP53 in-frame deletion mutations c.719_727delGTTCCTGCA (p53 p.Ser240_Cys242del) and c.634_642delTTTCGACAT (p53 p.F212_H214del) were detected in a single case of HGSC each. Both patients were postmenopausal women. Imaging and laboratory studies revealed peritoneal carcinomatosis and elevated levels of serum tumor markers. The patients underwent primary debulking surgery and were diagnosed as having stage IIIC HGSC. In both cases, p53 immunostaining revealed uniform nuclear immunoreactivity in 90% or more of tumor cells at a very strong intensity. Targeted genomic sequencing revealed novel in-frame deletion mutations of TP53 leading to p53 overexpression in tubo-ovarian HGSC. This discovery of previously unreported somatic TP53 mutations provides insight into the translation of NGS technology into personalized medicine and identifies new potential targets for therapeutic applications.