Introduction/Background Advanced ovarian carcinomas (AOC) not amenable to up-front surgery are treated with neoadjuvant chemotherapy (NACT) before interval debulking surgery (IDS). Based on a semi-mechanistic model, the CA125 ELIMination rate constant K (KELIM) is a reproducible indicator of the tumor-primary chemosensitivity: KELIM >1 is linked with good response to platinum and favorable prognosis. The 3-tier system chemotherapy response score (CRS) is a scoring system based on post-NACT histopathological evaluation, with significant correlation to progression free survival and mixed results for overall survival.

Methodology This is a monocentric retrospective case series. We recorded KELIM (3 CA125 values during the first 100 days of NACT with Carboplatin AUC5 plus Paclitaxel 175 mg/mq q21) and CRS score (1: minimal response; 2: moderate response with residual neoplastic foci; 3: complete or near-complete response, with no residual neoplastic cells or minimal residual up to 2 mm in maximum size). The ordinal logistic regression model was used to detect and estimate statistical correlation between KELIM and CRS.

Results From 11/2019 to 11/2022, 29 women with AOC were treated with NACT followed by IDS at National Cancer Institute of Milano. Median age was 60,5(53–80) years. All patients had a high-grade serous carcinoma; 62% patients had BRCA 1/2 mutations. All patients performed at least 3 cycles of NACT and underwent IDS within 30 days to the end of CT. Six (21%), 16(55%) and 7(24%) patients had CRS equal to 1, 2 and 3 respectively. For the three groups the median value of KELIM was respectively 0.41, 1.07 and 1.92 (Odds Ratio: 10.5, p-value: 0.002).

Conclusion Although the case series was small, we detected a straight correlation between KELIM and CRS in neoadjuvant setting. The tumor chemosensitivity assessed by KELIM during NACT could be a decision-making factor to consider before IDS. Mathematical modeling of KELIM is feasible and reproducible in real life.

Disclosures No disclosure to declare