793P Strong relationships between the CA-125 KELIM score and the tumor biological effects after neo-adjuvant chemotherapy in advanced ovarian cancer patients: CHIVA trial (GINECO)

The modeled CA-125 longitudinal kinetic parameter KELIMTM during 1st-line chemotherapy is as a pragmatic indicator of the tumor primary chemosensivitiy. However, the links between KELIMTM and the beneath chemotherapy-induced tumor biological effects had to be explored. We studied the links between KELIMTM values and pathological response, and changes in TILs, in ovarian cancer patients treated with neo-adjuvant chemotherapy (NACT) +/- interval debulking surgery (IDS). In the randomized phase II trial CHIVA (NCT01583322), 188 patients were treated with NACT carboplatin-paclitaxel +/- nintedanib, +/- IDS. Patient KELIMs were previously calculated. The pathological response was assessed with the Chemotherapy Response Score on the omentum (CRS 1-3), and with an enriched pathological response pR score based on the available tumor tissue block when omentum was lacking (pRS 1-3), obtained after NACT. Changes in stromal TILs (sTILs, % of the stromal surface on lymphocytes) and intra-epithelial TILs (ieTILs, qualitative appreciation, 0-2) in baseline tissue and after NACT were analyzed. A strong association was found between patient KELIMTM value and the omentum CRS after NACT (n=67; median KELIMTM, 0.71 for CRS-1; 1.26 for CRS-2; 1.66 for CRS-3; P<0.01). Consistent, a correlation was observed between KELIM and tumor pRS (n=103; median KELIMTM, 0.73 for pRS-1; 1.25 for pRS-2; 1.61 for pRS-3; P <0.01). At baseline before NACT, no relationships between KELIMTM and TILs were found. After NACT, a significant association was observed between higher patient KELIMTM values and higher intra-epithelial TILs infiltrate after NACT (n=99; median KELIM, 0.88 for ieTILs score 0-1; vs 1.26 for ieTILs score 2; P = 0.03). High consistency was found between patients KELIMTM and the pathological response after neo-adjuvant chemotherapy, assessed with the omentum CRS score, or the larger tumor pRS score. Omentum may not necessarily needed to assess the pathological response. Intra-epithelial TILs change after NACT was strongly associated with KELIMTM-assessed chemosensitivity, thereby opening hypotheses about mechanisms of platinum-sensitivity.