Abstract LB067: Extracellular enolase-1 drives cancer-associated fibroblast differentiation in the tumor microenvironment to enhance tumor growth of multiple myeloma: Development of the therapeutic antibody, HuL001

Abstract Multiple myeloma (MM), the second most prevalent hematologic malignancy, is driven by plasma cell proliferation within the bone marrow. Drug resistance in MM remains a significant challenge and the tumor microenvironment (TME) is generally believed to play a crucial role in the failure of drug treatment. This study aims to investigate extracellular enolase-1 (ENO1) as a dual-function regulator of MM progression and TME-driven resistance, with the goal of evaluating its therapeutic potential in MM. ENO1, initially recognized as a critical cytosolic enzyme in glycolysis, has emerged as a therapeutic target due to its “moonlighting” extracellular functions (in its surface-bound or secreted forms) for cancer treatments. Analysis of clinical MM samples revealed that high ENO1 expression correlates with poor patient prognosis, underscoring its clinical relevance. In vitro, we examined the effects of ENO1 on cell growth, cell migration, glycolysis, hypoxia-inducible factor 1-Ƈ (HIF-1Ƈ) expression, and cytokine secretion in MM cells. Co-culture systems of MM cells (or conditioned medium) and bone marrow stromal cells made it possible to assess the ENO1-mediated change of TME and its effects on glycolysis, cytokine secretion, and cancer-associated fibroblast (CAF) differentiation. ENO1-specific monoclonal antibody HuL001, which has completed a phase I safety trial (NCT04540770) was employed to explore the role of ENO1 in MM growth and its interaction with the TME. We demonstrated that extracellular ENO1 enhanced MM cell survival and migration via HIF-1Ƈ-mediated glycolysis. By using co-culture systems, we also concluded that ENO1 drove CAF differentiation to alter the TME by upregulating fibroblast activation protein (FAP), TGF-ƈ, and cytokines such as IL-6 and VEGF. In vivo, blocking ENO1 with HuL001 inhibited CAF-mediated tumor progression and enhanced lenalidomide efficacy in bortezomib (BTZ)-resistant MM xenograft model, probably by altering the TME and its interaction with MM cells. This is the first study to demonstrate that targeting extracellular ENO1 could reprogram the TME via inhibiting CAF to suppresses MM progression and overcome BTZ resistance. Given the satisfactory safety profile of ENO1 antibody (HuL001), these findings further support the ongoing clinical investigations of ENO1 as a therapeutic target to advance MM treatments. Citation Format: Maisie Huang, I-Che Chung, Yu-Tung Ko, Mao-Lin Chen, Tung-Yueh Chuang, Yung-Tsang Huang, Po-Yang Hsu, Ta-Tung Yuan. Extracellular enolase-1 drives cancer-associated fibroblast differentiation in the tumor microenvironment to enhance tumor growth of multiple myeloma: Development of the therapeutic antibody, HuL001 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB067.