Liquid Biopsy as a Powerful Therapeutic Tool in Veteran Patients with Prostate Carcinoma

Abstract

Abstract Introduction/Objective The National Comprehensive Cancer Network (NCCN) guidelines currently recommend somatic tumor molecular testing for alterations in homologous recombination (HR) DNA repair genes in patients with metastatic prostate cancer, which can be performed on either the sampled tumor tissue itself or by liquid biopsy. Particularly when the sampled tumor tissue may be limited, liquid biopsy with next generation sequencing is a recently available attractive alternative that is minimally invasive (requiring just phlebotomy). Based on the information gathered from circulating tumor cells (CTC), a tumor molecular profile can be obtained that can impact treatment, particularly if a HR DNA repair mutation is found as that may predict response to a poly (ADP-ribose) polymerase (PARP) enzyme inhibitor such as Olaparib. However, the literature of metastatic prostate cancers targeted by liquid biopsies and the mutations found is sparse, particularly for the veteran population. Methods/Case Report A retrospective review was performed of all patients with a submitted liquid biopsy specimen at a Veteran Affairs Medical Center (VAMC) October 23rd, 2019, to March 3rd, 2023 to examine those patients with metastatic prostate cancer. Information on mutations detected was collected. Results (if a Case Study enter NA) There were a total of 64 patient specimens with a history of metastatic prostate cancer, from which 56 had an available liquid biopsy report with the first liquid biopsy collection occurring on October 23rd, 2019. HR DNA repair mutations found included CHEK2 (6/56), ATM (4/56), and BRCA1 (1/56). Outside of HR DNA repair genes, relatively common detected mutations were found in TP53 (25/56), PTEN (6/56), BRAF (4/56), and an AR amplification (4/56). 7 of the 56 reports had no reportable genomic alterations detected. Conclusion Liquid biopsies continues to be a minimally invasive, highly useful powerful therapeutic tool in veteran patients with metastatic prostate carcinoma for molecular profiling. Not uncommonly in the Veteran population, these molecular findings include mutations in HR DNA repair genes that as noted by the NCCN may predict response to PARP inhibitor chemotherapy.