815MO The impact of chemosensitivity assessed by modeled CA-125 KELIM on the likelihood of long progression-free survivorship (PS) after 1st line treatment in ovarian cancer: An analysis of 4,450 patients

Primary tumor chemosensitivity plays an important but poorly understood role in the ovarian cancer patient prognosis. The modeled CA-125 kinetic parameter (KELIM) is an indicator of chemosensitivity, and is associated with survival (Clin Cancer Res 2019 & 2020; JNCI CS 2020). The objective was to assess the role of KELIM regarding the probability of long progression-free survivorship (PS) > 5 years after 1st line treatment. The datasets from 3 phase III trials in adjuvant setting (AGO-OVAR 9; AGO-OVAR 7 and ICON 7) were analyzed to explore the prognostic role of KELIM regarding the probability of PS in 2,868 stage (st) I-IV patients. An independent population-based cohort of 1,582 st II-IV patients in neo-adjuvant setting from The Netherlands Cancer Registry (NCR) was used as a validation dataset. Of 2,868 patients in the learning set (median 45-month follow-up), 82 patients (2.8%) were PS: 48 st I-II (PS probability (PSp) = 9.5%); 32 st III (PSp = 1.6%); 2 st IV (PSp = 0.5%). With favorable KELIM > 0.06 days-1, PSp increased to 12.0% for st I-II, 2.9% for st III & 2.1% for st IV. In multivariable logistic regression, higher FIGO stage (st I-II reference; st III, OR = 0.18 and st IV: OR = 0.06) and KELIM (OR = 2.35 [1.51-3.59]) were predictors of PS. Of 1,582 patients in the NCR dataset (median 95-month follow-up), 36 patients (2.7%) were PS: 2 st II (PSp = 22.2%); 26 st III (PSp = 2.8%); 8 st IV (PSp = 1.2%). With favorable KELIM, PSp increased to 5.4% for st III, and 2.4% for st IV. In multivariable regression, completeness of interval debulking surgery (OR = 6.25 [2.40-21.41]) and KELIM (OR = 3.82 [1.49-9.65]) were predictors of PS. PSp was 12% for st III with favorable KELIM and complete surgery. In an explorative set with 509 patients, the KELIM prognostic impact was more marked in BRCA wild-type and BRCA1 mutated patients, than in BRCA2. KELIM is an independent prognostic factor of progression-free survivorship > 5 years after 1st line treatment. The PSp is doubled in patients with favorable KELIM. The respective impacts of chemosensitivity and surgery relative to chance of potential cure are better understood.