Luo, Xin

Abstract Description Cholangiocarcinoma (CCA) is an aggressive epithelial malignancy of the bile duct, with rising global incidence and poor prognosis. Current treatments achieve only 20-30% response rates in advanced cases, highlighting the need for novel therapeutic approaches. The tumor microenvironment (TME) has emerged as a critical focus for innovative therapies. Sulfatase 2 (SULF2) is a heparan sulfate (HS)-editing enzyme that alters HS chain affinity for growth factors and receptors, modulating heparan sulfate proteoglycans (HSPG) in cell signaling pathways. Specific sulfatases in HSPGs have been implicated as therapeutic targets in CCA. This study investigates the potential of anti-SULF2 antibodies to modulate immune cells within the TME using a C57BL6 syngeneic mouse model. Anti-SULF2-treated mice were compared to untreated controls, with tumors analyzed via CyTOF. Treatment resulted in reduced immunosuppressive cells and increased anti-tumor immune cells, suggesting that SULF2 inhibition shifts the TME toward an anti-tumorigenic state. These findings highlight SULF2 as a promising target for therapeutic intervention. Future studies will explore spatial transcriptomic and proteomics to elucidate the interplay between SULF2 expression in the TME makeup. We will also explore the molecular mechanisms of SULF2 suppression and its influence on cytokine signaling pathways within the TME. Funding Sources Supported by CTSA Grant Number TL1 TR002380 from the National Center for Advancing Translational Science (NCATS). Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Upamostat is an orally available small-molecule serine protease inhibitor that is a highly potent inhibitor of trypsin 1, trypsin 2, trypsin 3 (PRSS1/2/3), and the urokinase-type plasminogen activator (uPA). These enzymes are expressed in many cancers, especially during tissue remodeling and subsequent tumor cell invasion. Opaganib (ABC294640), a novel, orally available small molecule is a selective inhibitor of the phosphorylation of sphingosine to sphingosine-1-phosphate (S-1-P) by sphingosine kinase 2 (SPHK2). Both sphingosine kinase 1 (SPHK1) and SPHK2 are known to regulate the proliferation-inducing compound S-1-P. However, SPHK2 is more critical in cancer pathogenesis. The goal of this project was to investigate the potential antitumor effects of upamostat and opaganib, individually and in combination, on cholangiocarcinoma (CCA) xenografts in nude mice. PAX165, a patient-derived xenograft (PDX) from a surgically resected CCA, expresses substantial levels of SPHK2, PRSS1, PRSS2, and PRSS3. Four groups of 18 mice each were treated with upamostat, opaganib, both, or vehicle. Mouse weights and PAX165 tumor volumes were measured. Tumor volumes in the upamostat, opaganib, and upamostat plus opaganib groups were significantly decreased compared to the control group.

Background and Aims Existing therapeutic approaches to treat cholangiocarcinoma (CCA) have limited effectiveness, prompting further study to develop therapies for CCA. We report a mechanistic role for the heparan sulfate editing enzyme sulfatase 2 (SULF2) in CCA pathogenesis. Approach and Results In silico analysis revealed elevated SULF2 expression in human CCA samples, occurring partly through gain of SULF2 copy number. We examined the effects of knockdown or overexpression of SULF2 on tumor growth, chemoresistance, and signaling pathway activity in human CCA cell lines in vitro. Up‐regulation of SULF2 in CCA leads to increased platelet‐derived growth factor receptor beta (PDGFRβ)–Yes‐associated protein (YAP) signaling activity, promoting tumor growth and chemotherapy resistance. To explore the utility of targeting SULF2 in the tumor microenvironment for CCA treatment, we tested an anti‐SULF2 mouse monoclonal antibody, 5D5, in a mouse CCA xenograft model. Targeting SULF2 by monoclonal antibody 5D5 inhibited PDGFRβ–YAP signaling and tumor growth in the mouse xenograft model. Conclusions These results suggest that SULF2 monoclonal antibody 5D5 or related agents may be potentially promising therapeutic agents in CCA.