Kristopher Sarosiek

Hypoxia induced VEGF secretion promotes resistance to bispecific T-cell engagers

Abstract Bispecific T-cell Engagers (BITEs) are a novel form of immunotherapy that overcome a deficiency of immune checkpoint inhibitors (ICI) by targeting a preidentified tumor associated antigen and redirecting a polyclonal population of effector T-cells against the tumor. High grade serous ovarian cancer is a lethal disease in the recurrent setting and has not been amenable to ICI therapy. MUC16/CA125 is overexpressed in high grade serous ovarian cancer. BITEs targeting the tumor-retained portion of MUC16/CA125 have recently been described and are in early-phase clinical trials. To identify mechanisms of resistance to BITEs, we collected serum, peripheral blood mononuclear cells, and ascites samples from patients with disease progression on MUC16-directed bispecific antibodies. Analysis of these samples showed downregulation of MUC16/CA125, elevated secretion of VEGF, and epithelial-to-mesenchymal transition in tumor cells. Interestingly, hypoxia was determined to be a driver of these changes. These findings were prospectively validated in ovarian cancer cell lines with CRISPR/Cas9 knockout of MUC16/CA125 and VEGF. Peripheral blood mononuclear cells from patients with disease progression were capable of effective cytolysis ex vivo, suggesting that resistance to therapy was primarily tumor driven. Restoration of MUC16/CA125 expression did not restore cytotoxicity in the presence of increased VEGF secretion. Combination treatment with a VEGF inhibitor rescued cytotoxicity in hypoxia-conditioned ovarian cancer cell lines with preserved target antigen expression. Collectively, these data outline a link between hypoxia and the development of resistance to BITEs and posits inhibition of VEGF inhibition as a potentially important therapeutic intervention.

Targeting Galectin 3 illuminates its contributions to the pathology of uterine serous carcinoma

Abstract Background Uterine serous cancer (USC) comprises around 10% of all uterine cancers. However, USC accounts for approximately 40% of uterine cancer deaths, which is attributed to tumor aggressiveness and limited effective treatment. Galectin 3 (Gal3) has been implicated in promoting aggressive features in some malignancies. However, Gal3’s role in promoting USC pathology is lacking. Methods We explored the relationship between LGALS3 levels and prognosis in USC patients using TCGA database, and examined the association between Gal3 levels in primary USC tumors and clinical-pathological features. CRISPR/Cas9-mediated Gal3-knockout (KO) and GB1107, inhibitor of Gal3, were employed to evaluate Gal3’s impact on cell function. Results TCGA analysis revealed a worse prognosis for USC patients with high LGALS3. Patients with no-to-low Gal3 expression in primary tumors exhibited reduced clinical-pathological tumor progression. Gal3-KO and GB1107 reduced cell proliferation, stemness, adhesion, migration, and or invasion properties of USC lines. Furthermore, Gal3-positive conditioned media (CM) stimulated vascular tubal formation and branching and transition of fibroblast to cancer-associated fibroblast compared to Gal3-negative CM. Xenograft models emphasized the significance of Gal3 loss with fewer and smaller tumors compared to controls. Moreover, GB1107 impeded the growth of USC patient-derived organoids. Conclusion These findings suggest inhibiting Gal3 may benefit USC patients.