Abstract 6899: Investigating the impact of CXCR6 antagonism on Wnt/β-catenin signaling and sorafenib resistance development

Abstract Introduction: Due to its heterogeneity, hepatocellular carcinoma (HCC) has a high incidence of resistance and toxicity to its first-line therapy sorafenib. Combinations of drugs can be used to exploit synergistic effects to improve efficacy and reduce adverse events. Upregulation of C-X-C chemokine receptor type 6 (CXCR6) and its ligand has been observed in multiple cancers and has been used as a predictor of cancer recurrence and poor prognosis in HCC. Increased CXCR6 signaling has been shown to promote Wnt/β-catenin signaling, a pathway known to be dysregulated in 50% of HCC and involved in sorafenib resistance. We have developed SBI-457, an orally bioavailable small molecule CXCR6 inhibitor, which decreased tumor growth in a murine HCC model. In this study, we test the efficacy of combining SBI-457 and sorafenib in mitigating the development of resistance and increasing sensitivity to drug treatment in HCC. Experimental Procedure: An HCC cell line-derived xenograft model was generated by injecting HCC cell line SKHep1 subcutaneously in the flank of male NOD.Cg-PrkdcscidIL2rgtm1Wjl/SzJ (NSG) mice. Mice were treated with vehicle, sorafenib, SBI-457, or sorafenib and SBI-457 in combination; mouse tumor volumes and weights were tracked for the duration of study. Mice were all euthanized at study endpoint, and tissues collected for analysis, including assessment of tumor proliferation, invasion, and CXCR6 and β-catenin expression levels. Results: SKHep1 tumors treated with sorafenib and SBI-457 in combination were significantly reduced in tumor volume and weight compared to vehicle. Mice treated with SBI-457 alone or in combination with sorafenib maintained stable weight and had no observed toxicity due to treatment. CXCR6 expression was slightly elevated in the sorafenib only treated group and reduced in the groups treated with SBI-457 alone. Western blot and IHC analysis confirmed that treatment with SBI-457 increases active (non-phosphorylated) GSK-3β and decreases β-catenin expression, while sorafenib treatment resulted in an increased phosphorylated GSK-3β and (non-phosphorylated) active β-catenin expression. This sorafenib-induced increase in β-catenin was attenuated by combination treatment with SBI-457. Conclusion: This study demonstrated that treatment with CXCR6 antagonist, SBI-457, in combination with sorafenib was able to significantly reduce tumor burden compared to vehicle. Additionally, combination therapy seems to attenuate the sorafenib-induced increase in β-catenin expression, indicating that CXCR6 inhibition could help mitigate sorafenib resistance development. Citation Format: Anastasia G. Chambers, Abhishek Shrestha, Morgan Reeves, Alivia Cullu, Lauren Donohue, Sergio Duarte, Satyamaheshwar Peddibholta, Siobhan Malany, Ali Zarrinpar. Investigating the impact of CXCR6 antagonism on Wnt/β-catenin signaling and sorafenib resistance development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6899.