1276 The Diagnostic landscape and clinical outcomes associated with homologous recombinant deficiency (indicator one): results and one-year trends from a survey of physicians and molecular pathologists

Introduction/Background About half of newly diagnosed high-grade serous and endometrioid epithelial ovarian cancers have homologous recombination deficiency (HRD). Tumors with HRD demonstrate synthetic lethality with poly(ADP-ribose) polymerase inhibitors (PARPi), and HRD testing is pivotal in management of advanced ovarian cancer (AOC) patients where PARPi treatment is considered. Treatment guidelines incorporate PARPi maintenance following first-line chemotherapy, highlighting HRD test value. This survey characterizes current HRD testing practices and shifts over time. Methodology This is a non-interventional, cross-sectional, web-based survey of US and European (UK, France, Germany, Austria) physicians and clinical laboratory heads/molecular pathologists. Two survey waves are complete (Wave 1: July-November 2022; Wave 2: June-September 2023). For wave 2, the survey was slightly amended. Recruitment was via a standing physician panel and clinical sites/laboratories. Results 347 participants completed wave 2 (278, 80.1% physicians; 69, 19.9% clinical laboratory heads/molecular pathologists; 105, 30.3% completed wave 1 and 2). A small numerical increase in the proportion of newly diagnosed AOC patients tested was reported. In wave 1, myChoice (Myriad Genetics) use was twice as frequent as FoundationOne (Foundation Medicine) in Europe, although use of these tests was similar in wave 2. In-house laboratory developed test use remained low. Of European participants using myChoice or FoundationOne, more reported sending tests to domestic centralized labs than in wave 1. In wave 2, fewer tests in Europe and more tests in the US were fully reimbursed/subsidized. Median time to receiving test results, although still longer than turnaround in the US, was reduced in Europe. Conclusion European wave 2 results differ slightly from wave 1, in terms of test types reported, and more tests performed domestically. Shifts in testing practices may be due to lower reimbursement/subsidization for tests in Europe. These changes in testing practices indicate the direction of future research and identification of potential areas of improvement to increase HRD testing. Disclosures RLC received research grants or support from AstraZeneca/Medimmune, Clovis Oncology, Merck, Immunogen, Mirati Therapeutics, Amgen, Pfizer, Lilly, Regeneron; served in consultant/advisory roles for Clovis Oncology, Genentech/Roche, AstraZeneca/Medimmune, Genmab, OncoMed, Immunogen, Abbvie, Agenus, Novocure, Merck, OncXerna Therapeutics, Alkermes, Gradalis, GSK, Eisai, GOG Foundation, Karyopharm Therapeutics; has a family member that received research funding from Roche/Genentech; is employed by US Oncology; has leadership roles with Onxeo; has had travel, accommodations, and expenses paid by Merck, AstraZeneca/Medimmune, Array BioPharma, Clovis Oncology, Roche/Genentech, Research to Practice, GOG Foundation, Sotio, Vaniam Group. MH, CI, EJ, and TS are employees of AstraZeneca. MH, CI, and EJ are stockholders at AstraZeneca; CI is also a stockholder of Bristol-Myers Squibb and Pfizer. BS and DRC are employees of ICON Commercial Solutions. AL served in consultant/advisory roles for AstraZeneca, Clovis Oncology, GlaxoSmithKline, MSD, Merck Serono, Ability, Zentalis, Agenus, and Blueprint Medicines; received research grants or support from AstraZeneca, Clovis Oncology, GlaxoSmithKline, MSD, Ability, Zentalis, Agenus, Iovance, Sanofi, Roche, OSEimmuno, and BMS; received travel/accommodation expenses from AstraZeneca, Clovis, and GlaxoSmithKline.