Abstract LB081: GAS6-AXL inhibition by AVB-500 overcomes resistance to paclitaxel in endometrial cancer by decreasing tumor cell glycolysis

Abstract Objective/Background: Chemotherapy is often ineffective in advanced stage and aggressive histologic subtypes of endometrial cancer. Overexpression of the receptor tyrosine kinase AXL has been found to be associated with therapeutic resistance, metastasis, and poor prognosis in endometrial cancer. Our objective was to identify whether inhibition of AXL through a novel, selective targeted agent, AVB-500, would improve sensitivity to paclitaxel. Additionally, we sought to determine whether the mechanism for this improved sensitivity was through metabolic regulation. Methods: Immunohistochemistry (IHC) was performed on a tissue microarray containing specimens from patients with primary and metastatic uterine serous carcinoma. Blind scoring was performed by two reviewers. Kaplan-Meier methods were used to generate time-to-event curves. Cell viability was performed with high-grade endometrial, chemo-resistant cell lines, ARK1 and PUC198. Cells were treated with paclitaxel and with AVB-500+paclitaxel. Intraperitoneal (IP) ARK1 or PUC198 tumors were treated with vehicle, AVB-500, paclitaxel, or AVB-500+paclitaxel. A Seahorse Analyzer was used for glycolytic rate assays. Isotope tracing was used for in vivo metabolite abundance quantification. Results: We found that both GAS6 and AXL expression were higher by IHC in tumors with a poor response to chemotherapy compared to tumors with a good response to chemotherapy (GAS6: 40.9% vs. 30.4%, P=0.012; AXL: 60.7% vs. 42.7%, P=0.013). Median PFS and OS were longer in patients with low GAS6 expressing tumors compared to high GAS6 expressing tumors (PFS: 33.6 mo vs. 10.6 mo, P=0.003; OS: 39.5 mo vs. 27.7 mo, P=0.003). We showed that chemotherapy resistant endometrial cancer cell lines, ARK1 and PUC198 had improved sensitivity and synergy with paclitaxel when treated in combination with AVB-500. ARK1 and PUC198 in vivo IP models had significantly fewer tumors (ARK1: P=0.007; PUC198: P=0.029) and decreased tumor weight (ARK1: P<0.001; PUC198: P=0.006) when treated with AVB-500+paclitaxel vs. paclitaxel alone. Treatment with AVB-500 + paclitaxel decreased AKT signaling which resulted in a decrease in basal glycolysis. Finally, treatment with AVB-500 + paclitaxel decreased multiple glycolytic metabolites, including fructose-1,6-bisphosphate (P=0.002), 3-phosphoglyceric acid (P=0.014), phosphoenolpyruvate (P=0.013), and lactate (P=0.024) vs. treatment with paclitaxel alone. Conclusions: Our study provides strong pre-clinical rationale for combining AVB-500 with paclitaxel in aggressive endometrial cancer models. Additionally, continued identification of viable biomarkers is critical to the success of targeted therapies such as AVB-500. Given AXL’s role in glucose homeostasis, one or more glycolytic intermediates may prove to be a useful biomarker to help predict sensitivity in patients, thus tailoring who would benefit from this treatment combination. Citation Format: Shaina F. Bruce, Kevin Cho, Hollie Noia, Elena Lomonosova, Elizabeth Stock, Alyssa Oplt, Barbara Blachut, Mary M. Mullen, Lindsay M. Kuroki, Andrea R. Hagemann, Carolyn K. McCourt, Premal H. Thaker, Dineo Khabele, Matthew A. Powell, David G. Mutch, Leah P. Shriver, Gary J. Patti, Katherine C. Fuh. GAS6-AXL inhibition by AVB-500 overcomes resistance to paclitaxel in endometrial cancer by decreasing tumor cell glycolysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB081.