46MO What are the predictors of the success of interval debulking surgery (CC0-IDS) in patients with advanced ovarian cancers? Consistent data from two large independent datasets

Over 50% of advanced epithelial ovarian cancer patients undergo neoadjuvant chemotherapy (NACT), aiming to achieve a complete interval debulking surgery (IDS). Understanding the factors that can predict IDS success is crucial. The French GINECO and the Gemelli (Italy) groups analyzed two independent datasets, separately. The French dataset included 133 patients from the CHIVA (C) randomized phase II trial (NCT01583322). The Italian dataset was built with the Policlinico GEMELLI (G) real-life registry with 357 patients (ID5936–ProtN45). Univariate/multivariate logistic regression models were performed to examine the clinical and biological covariates associated with: 1) low peritoneal carcinomatosis index (PCI) after 3/4 NACT cycles (Sugarbaker PCI ≤ 10 or Fagotti score at IDS ≤ 2); 2) IDS with no macroscopic residual lesion (CC0), 3) Complete or near-complete pathological response according to chemotherapy response score (CRS3). The assessed predictor factors were the modeled CA-125 longitudinal kinetics parameter KELIM, considered as a continuous (KCont) value or as Favorable (≥ 1; FavK) vs Unfavorable (<1; UnFavK); best radiological response according to RECIST 1.1; and BRCA mutation/homologous recombination deficiency (HRD) status (C: Shallow HRD; G: Myriad O.R. FavK vs UnFavK: (C) 4.19 1.76-10.71 - (G) 2.92 1.58-.39 - higher rates of complete IDS-CC0: O.R. KCont: (C) 7.29 3.38-17.13 - (G) 4.66 1.89-11.48; O.R. FavK vs UnFavK: (C) 4.24 2.07-8.99 - (G) 3.66 1.67-8.01 - higher probability of CRS3: O.R. KCont: (C) 12.43 3.75-55.5 - (G) 2.97 1.82-4.84; O.R. FavK vs UnFavK: (C) 21.44 4.15-394.01 - (G) 2.36 1.51-3.70. The best radiological response was inconsistently significant. The BRCA/HRD status was not predictive of IDS success. Across 2 independent international datasets, the primary tumor's chemosensitivity, assessed by CA-125 KELIM, was the sole consistent predictor of IDS success after NACT.