ObjectiveTreatment of high-grade serous ovarian carcinomas relies on surgery and chemotherapy, potentially followed by bevacizumab and/or poly (ADP-ribose) polymerase inhibitors (PARPi). The modeled CA-125 ELIMination rate constant K (KELIM) is a pragmatic indicator of tumor primary chemosensitivity. Although it is well established thatBRCAmutations are associated with platinum sensitivity, the relationship betweenBRCAstatus and KELIM score has yet to be elucidated. This study aimed to evaluate the interactions betweenBRCAand KELIM, and their respective prognostic values.MethodsWe retrospectively collected data from 743 patients with high-grade serous ovarian carcinomas included in a French nationwide registry (NCT03275298) treated with neoadjuvant platinum-based chemotherapy followed by surgery. We analyzed the interactions betweenBRCAand KELIM, and their impacts on progression-free survival and overall survival.ResultsBRCA-mutated(BRCAm) patients had higher standardized KELIM thanBRCA-wild type (BRCAwt) tumors (median 1.16 vs 1.06, respectively; p=0.001). The prognostic value of the KELIM score was independent ofBRCAin multivariate analyses. KELIM score andBRCAcould be combined to define three prognostic groups: (1) an unfavorable prognostic group with bothBRCAwt and unfavorable KELIM (median progression-free survival 12.0 months); (2) an intermediate prognostic group with eitherBRCAm and unfavorable KELIM, orBRCAwt and favorable KELIM (median progression-free survival of 16.0 and 18.8 months, respectively; HR 0.64 compared with the unfavorable group, p<0.001); and (3) a favorable prognostic group with bothBRCAm and favorable KELIM (median progression-free survival 28.8 months; HR 0.37 compared with the unfavorable group, p<0.001).ConclusionsThe KELIM score provides complementary prognostic information with respect toBRCA,and discriminates different prognoses withinBRCAm orBRCAwt patients. Patients with bothBRCAwt/unfavorable KELIM have a poor prognosis, underscoring the urgent need for novel therapeutic strategies.