Abstract 3288: Identification of Annexin A1 as a novel driver of lenvatinib resistance in hepatocellular carcinoma

Abstract Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. Lenvatinib has recently been approved by the FDA for front-line treatment of HCC patients at advanced stages. However, the survival benefit of lenvatinib is modest due to the development of acquired drug resistance. In this study, we aimed to investigate the mechanisms underlying lenvatinib resistance in HCC and to identify potential therapeutic targets to combat lenvatinib resistance. For this purpose, we established a lenvatinib-resistant (LenR) HCC patient-derived tumor xenograft (PDTX) by administering four rounds of lenvatinib treatment, and their genetic profiles were analyzed using single-cell RNA sequencing (scRNA-seq). Based on single-cell regulatory network inference and clustering (SCENIC) analysis, Annexin A1 (ANXA1), the top gene that was enriched in the HCC cell-like cluster of LenR tumors, was identified and was consistently observed in LenR HCC cell lines and LenR tumors derived from Tp53KO/C-MycOE and RIL175 HCC mouse models. Using an in vitro differentiation model, limiting dilution assay, apoptosis assay and correlation analysis, we demonstrated the role of ANXA1 in the regulation of cancer stemness-driven lenvatinib resistance. Mechanistically, ANXA1 regulates cancer stemness and drug resistance by driving the STAT3/S100A6 signaling cascade, and ANXA1 expression is regulated by SOX2 via promoter activation, as demonstrated by a chromatin immunoprecipitation (ChIP) assay. Using the same set of scRNA-seq data, we showed that LenR HCC tumors reshaped the tumor microenvironment (TME) by inducing M2 macrophage polarization, as evidenced by a higher M2/M1 ratio of tumor-associated macrophages (TAM) in LenR HCC tumors than in their mock counterparts. Based on this observation, we further demonstrated the in vitro role of secretory ANXA1 in LenR HCC cells in inducing macrophage polarization towards the M2 phenotype. In conclusion, ANXA1 may regulate lenvatinib resistance intrinsically via the promotion of cancer stemness and extrinsically via the induction of an immunosuppressive TME. Citation Format: Catherine Yujia GU, Carmen Oi Ning LEUNG, Terence Kin Wah LEE. Identification of Annexin A1 as a novel driver of lenvatinib resistance in hepatocellular carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3288.