Prognostic Role of CA-125 Elimination Rate Constant (KELIM) in Patients with Advanced Epithelial Ovarian Cancer Who Received PARP Inhibitors

Simple Summary Prior research has identified various prognostic markers in epithelial ovarian cancer (EOC), including BRCA mutation status and a response to platinum-based chemotherapy, to predict outcomes in patients undergoing PARP inhibitor maintenance therapy. The role of CA-125 elimination rate constant K (KELIM), although recognized as a prognostic indicator, has not been fully investigated. This study underscores the prognostic significance of KELIM, revealing that a favorable KELIM score significantly correlates with better PFS in patients treated with primary cytoreductive surgery (PCS) followed by PARP inhibitor therapy. It also shows that KELIM's predictive value varies with the timing of surgery, extending a different view of its utility in real-world practice. KELIM could be integrated into clinical decision-making processes, potentially informing future clinical guidelines and research into optimal treatment strategies for targeted use of PARP inhibitors in advanced EOC patients.Abstract Background: This multicenter retrospective study aimed to investigate the prognostic value of the CA-125 elimination rate constant K (KELIM) in EOC patients who received platinum-based chemotherapy followed by PARP inhibitors, in either upfront or interval treatment settings. Methods: Between July 2019 and November 2022, we identified stage III-IV EOC patients who underwent primary or interval cytoreductive surgery and received olaparib or niraparib. Individual KELIM values were assessed based on validated kinetics and classified into favorable and unfavorable cohorts. Results: In a study of 252 patients undergoing frontline maintenance therapy with olaparib or niraparib, favorable KELIM (>= 1) scores were associated with a higher PFS benefit in the primary cytoreductive surgery (PCS) cohort (hazard ratio (HR) for disease progression or death 3.51, 95% confidence interval (CI); 1.37-8.97, p = 0.009). Additionally, within the interval cytoreductive surgery (ICS) cohort, a favorable KELIM score (>= 1) significantly increased the likelihood of achieving complete resection following cytoreductive surgery, with 59.4% in the favorable KELIM group compared to 37.8% in those with unfavorable KELIM. Conclusions: A favorable KELIM score was associated with improved PFS in patients with advanced EOC undergoing PCS. Furthermore, in the ICS cohort, a favorable KELIM score increased the probability of complete cytoreduction.