BRCA tumor test in ovarian cancers: The changing role of molecular pathology in the era of PARP inhibitor (PARPi) therapy.

Abstract

5572 Background: The PARPi Olaparib has been approved in maintenance setting of recurrent platinum-sensitive and BRCA mutated, ovarian cancer (OC) patients. However, according to the striking results of SOLO 1 trial, it could be shortly proposed even to newly diagnosed BRCA mutated OC women. We report the results of the implementation of tumor BRCA test in diagnostic setting within the frame of institutional workflow for the management of OC patients. Methods: 223 women with OC were consecutively referred over 25 months to tumor BRCA test. The test was requested by gynecologic oncologist at the diagnosis of non-mucinous and non-borderline OC, upon discussion on the implications of the test result and written consent collected for each patient. Formalin-fixed paraffin embedded (FFPE) specimens of OC were tested using the automatized “Oncomine BRCA Research Assay” Next Generation Sequencing (NGS) panel. The tumor BRCA test was also performed on 5 archetypal cytological samples from ascites. Results: All the cases were considered adequate for the NGS analysis according to the tumor cell content (more than 10%) and the DNA yield extracted (more than 10 ng). The tumor BRCA test had a successful rate of 99.1% . The median Turn-Around Time (TAT) was 17 calendar days, from 33 days of the first trimester to 14 days of the last trimester of this analysis. Overall BRCA1 or BRCA2 pathogenic (P)/likely pathogenic (LP) mutations were found in 62 (28.1%) cases and variants of uncertain significance (VUS) in 25 (11.3%) cases, including 3 cases with a BRCA1 P variant and a concurrent BRCA2 VUS alteration. In detail, 47 P/LP variants and 16 VUS were identified in BRCA1 whereas 15 P/LP mutations and 9 VUS occurred in BRCA2. Complete concordance in tumor BRCA test results were seen between ascites cytological samples and matched tumors. Conclusions: The tumor BRCA test could be implemented in routine diagnostic setting, at diagnosis of non-mucinous and non-borderline OC. The test could be performed on FFPE specimens, had an high successful rate and a TAT compatible with clinical needs. The promising data on cytological samples will be confirmed in larger series.