A Prospective, International, Multi-center, Interventional Trial of Advanced Epithelial Ovarian Cancer Patients Offered Three Cycles of Neoadjuvant Chemotherapy (NACT) and Triaged With KELIM Score. Patients With Favorable Score Will Undergo Interval Debulking Surgery (IDS) Followed by Another 3 Cycles of NACT, While Those With Unfavorable Will Undergo Another 3 Cycles of NACT Followed by Delayed Interval Debulking Surgery (DIDS).

Primary debulking surgery (PDS) followed by adjuvant chemotherapy is the cornerstone of advanced ovarian cancer treatment. However, frail patients, patients with high tumor burden in the upper abdomen or extra-abdominal metastases may benefit from neoadjuvant chemotherapy (NACT) followed by interval debulking surgery (IDS). In recent years, three randomized non-inferiority trials have demonstrated that NACT is a valid alternative to PDS. Similarly, the preliminary results from the TRUST trial showed that the primary endpoint of overall survival (OS) was not met, with numerical longer OS in PDS group compared to NACT in non-frail ovarian cancer patients. The optimal number of NACT cycles has not yet been established. Most studies in the literature recommend 3-4 cycles. However, in real-world clinical practice some patients receive more than 5 cycles before surgery, so delayed interval debulking surgery (DIDS) is proposed as an alternative. The rationale is to allow for maximal tumor shrinkage and improved likelihood of complete gross resection, while reducing perioperative morbidity. Retrospective data show that DIDS may be considered as an alternative for advanced ovarian cancer patients with a high tumor burden, when complete gross resection cannot be achieved during IDS.

Furthermore, the success of the above-mentioned treatment plans depends on tumor chemosensitivity and the ability to achieve complete gross resection, because residual disease after cytoreduction remains the most important prognostic factor. On the other hand, 15-20% of patients with advanced ovarian cancer will be poor responders to chemotherapy, so there is the need for accurate non-invasive chemo-sensitivity predictors to guide treatment decisions in the first-line setting, which is acknowledged by ESGO and ESMO. Monitoring of CA-125 decline during chemotherapy for the prediction of treatment response (13) and as a way to overcome imaging limitations, has been one of the main points of research in ovarian cancer patients. The ELIMination rate constant K (KELIM), a modeled kinetic parameter based on CA-125 measurements during the first 100 days of systemic therapy (adjuvant of neoadjuvant chemotherapy), has emerged as a valuable predictor. It is a mathematical modeling method based not on absolute values of the biomarker, but on the longitudinal kinetics (CA-125 elimination) during treatment, completely independent of renal function. Retrospective data show that KELIM score is an independent prognostic biomarker for survival outcomes, that can predict chemosensitivity, and that can safely triage patients undergoing NACT and guide who will benefit from IDS and DIDS, respectively.