214eP Exploratory biomarkers evaluation to enhance characterization and explore treatment response prediction in metastatic ovarian cancer patients undergoing therapy with EVT801, a highly selective VEGFR-3 inhibitor
Résumé
Background EVT801 is a potent (IC50 = 11 nM) and selective inhibitor of VEGFR3 (10-fold selectivity over other VEGF receptors). Methods NCT05114668 is a phase 1 study to evaluate the safety, tolerability and pharmacokinetics of EVT801 in patients with advanced solid tumors. Dose escalation followed a 3+3 design, with a starting dose of 50 mg QD. Eligible patients had advanced pretreated solid tumors, with good performance status (ECOG 0-1), adequate organ function and evaluable disease. The Dose Limiting Toxicity (DLT) period was 28 days. Results Twenty-six patients were treated by EVT801 between October 2021 and November 2024 (LPLV) at two French clinical centers. Most common tumor type was ovarian cancer (11/26). The median age was 66 (range 40-76) years. The most common adverse events were fatigue, diarrhea, nausea and vomiting. One patient experienced a DLT at 400 mg BID. 500 mg BID was the maximum tolerated dose (MTD) and 400 mg BID was selected as the recommended phase 2 dose (RP2D) for monotherapy based on the incidence of TEAE beyond the DLT period. Partial response was seen in 1/26 patients, with 10 patients having SD for 3 months or longer. Volumetric assessment analysis of metastases by an external imaging research organization (Radiomics.bio) has demonstrated that liver lesions showed a stronger response to the therapy as compared to lung lesions. Moreover, patients with stable disease (SD) after one cycle of treatment showed an increase of circulating CD8+ T-cells and a decrease of CD4+ Treg-cells in comparison to patients with progressive disease. We have also observed that for patients with High Grade Serous Ovarian Cancer, levels of VEGFR3 expression had a negative correlation with CD8+ T-cells infiltration in the tumor microenvironment and a tendency to positive correlation with a PD1 mAb resistance signature. Conclusions EVT801 showed encouraging signs of clinical activity in advanced ovarian cancer patients. These data support future biomarker-driven clinical development as monotherapy or in combination with established therapies for high-grade serous ovarian cancer.
