Introduction/Background BRCA mutation and homologous recombination deficiency (HRD) are used to administrate PARPi maintenance therapy. It is known that PARPi efficacy and platinum sensitivity have some relationship and that the latter can be demonstrated from the CA-125 elimination rate constant (KELIM). KELIM is a modeled kinetic parameter based on CA-125 values measured during the first 100 days of neoadjuvant or adjuvant chemotherapy. This study aims to investigate if KELIM can be another tool in the identification of patients that benefit from PARPi therapy.

Methodology We retrospectively analyzed the records of patients with high-grade serous advanced ovarian cancer that were treated in the 1st Department of Obstetrics – Gynecology Clinic and further tested for HRD status. The HRD status was tested either by myChoice HRD CDx assay or by RediScore assay. KELIM score was measured in both neoadjuvant and adjuvant settings with the online tool biomarker-kinetics.org.

Results Thirty-nine patients had available data for both HRD and KELIM. The mean age of the patients was 60 years old and 22 (56.4%) underwent neoadjuvant, while 17 (43.6%) underwent adjuvant chemotherapy. From the available data, 27/31 (87%) had complete or optimal cytoreduction. When assuming KELIM as a binary index test with the value 1 as the cut-off point, the sensitivity was 0.86, 95% CI (0.64–0.97), and the specificity 0.83, 95% CI (0.59–0.96). On the other hand, when assuming KELIM as a continuous index test, the AUC was 81% and the optimal threshold, using the Youden index, was identified as 1.03 with a sensitivity of 85.7%, and a specificity of 83.3%.

Conclusion KELIM score seems to be a new, cheaper and faster tool to identify patients that can benefit from PARPi maintenance therapy. Further prospective trials are needed to validate these results.

Disclosures No disclosures