Oligometastatic prostate cancer patients stratification: A molecular signature identified by liquid biopsy.

Abstract

TPS400 Background: Oligometastatic prostate cancer (OPC) may represent the initial step of an unavoidable, rapid progression to a polymetastatic state, or the expression of a real oligometastatic phenotype related to a condition of stable disease for a long time. In the last scenario, stereotactic body radiation therapy (SBRT) can be considered as a potentially curative treatment option for hormone-naïve OPC. We propose a prospective, explorative trail with the aim of identifying by liquid biopsy a molecular signature (genes or differential expression of miRNA), and related clonal evolution, underlying metastatic prostate cancer progression after a course of SBRT. Methods: Study population will be 30 adult, hormone-naïve OPC undergoing SBRT. Table 1 summarizes gene and miRNA panel for molecular analysis. For each patient, 15 ml of peripheral blood will be collected before and at the end of SBRT, every 3 months for the first year, then every 6 months until disease progression, when another blood sample will be collected in case of instrumental evidence of failure (using PET-Choline or CT-scan plus bone scintigraphy). 7.5 ml of peripheral blood will be centrifuged to separate sera and 7.5 ml of peripheral blood will be centrifuged to separate plasma from the other blood components, respectively. Sera and plasma will be stored at -20°C and centralized to CREA Laboratory at our Institution, then immediately processed for cell free DNA (cfDNA) and miRNA extraction for NGS of target genes (by Illumina platforms MiSeq and MiniSeq) and dPCR analysis. Study duration will be 36 months. This protocol has been written and will be conducted in agreement with either the Declaration of Helsinki and subsequent amendments and ICH Harmonized Tripartite Guideline for Good Clinical Practice, and has received approval of local Ethics Committee. Panel for analysis. [Table: see text]