Introduction/Background CA125 decline, assessed by the CA-125 elimination rate constant K (KELIM) model, is associated with HGSOC intrinsic chemosensitivity. KELIM score is correlated with benefit of adding bevacizumab to chemotherapy after primary debulking surgery in the ICON7 and GOG218 trials. However, benefit of bevacizumab after interval debulking surgery according to KELIM score has not yet been explored.

Methodology Data from FIGO stage III/IV HGSOC patients treated with neo-adjuvant chemotherapy were extracted from the real-life French ESME OC registry (NCT03275298). KELIM scores were calculated, standardized and scored as unfavorable if ≤ 1 or favorable if >1.

Results Of the 10,263 patients in the ESME OC cohort, KELIM was assessable in 743 HGSOC patients meeting the inclusion criteria, including 124 BRCA-mutated (BRCAm), 324 BRCA-wild type (BRCAwt) and 295 non-tested. Median follow-up was 50.3 months (mo). In PFS and OS multivariate analyses, FIGO stage, BRCA mutation, KELIM score and use of bevacizumab were significant (except bevacizumab which was only associated with PFS). Amongst the BRCA tested population, three different prognostic groups according to BRCA and KELIM statuses were identified: good prognosis associating BRCAm with KELIM>1 (median PFS 28.8 mo), poor with BRCAwt and KELIM≤ 1 (median PFS 12.0 mo), intermediate with either BRCAm/KELIM≤ 1 (median 16.1 mo) or BRCAwt/KELIM>1 (median 18.8 mo; with no significant PFS difference between those two intermediate prognosis groups; p = 0.58). Similar groups were identified according to OS. Bevacizumab was associated with a benefit in PFS in the overall population but the benefit in OS was only observed for patients with KELIM≤ 1 (median OS 47.2 mo versus 33.6 without bevacizumab; HR= 0.68; p = 0.014).

Conclusion KELIM and BRCA statuses are complementary prognostic tools in HGSOC patients. KELIM provides important information on the tumor intrinsic chemosensitivity beyond BRCA status that might help guide the optimal maintenance treatment including use of bevacizumab.