Targeted Liquid Biopsy Detects Tumor-Specific TP53 Mutations in Early and Late Stage Ovarian Cancer [29O

Abstract

INTRODUCTION: Ovarian cancer (OvCa) is the most lethal female reproductive tract malignancy. Despite the immediate need to detect these cancers at an earlier stage, there is no effective screening methodology or protocol. We hypothesized that the use of ultra-deep, targeted gene sequencing could detect somatic mutations in uterine lavage fluid, a next generation of liquid biopsy, as a means of molecular screening and diagnosis. METHODS: Paired tumor, uterine lavage and blood samples were collected and analyzed from patients undergoing debulking surgery. Lavage fluid was separated into cellular and acellular fractions and DNA isolated. A targeted next-generation (NGS) 56 gene panel was used. To rule out potential NGS-based errors, orthogonal mutation validation was performed using dPCR and Sanger sequencing. RESULTS: Tumor sequencing defined the distinct mutation profiles for all 9 patients; shared between all patients was TP53 mutations. We therefore focused our efforts on detecting TP53 mutations in the collected lavage samples. Using ultra-deep sequencing, and then a combination of mutation validation technologies, the identical TP53 mutation identified in the patients' tumor was detectable in 7/9 (77.8%) of the uterine lavage samples. Notably, both stage I cancers were detected by molecular analysis of the lavage fluid. CONCLUSION: Using a combination of molecular assays, all based on the analysis of uterine lavage fluid, we were able to detect tumor-specific TP53 mutations from 7/9 ovarian tumors including stage I cancers. The sensitivity of this approach to detect tumor-specific mutations, even in early stage disease, highlights the potential for a molecular screening test for OvCa.