Immune modulation of calcium/calmodulin dependent protein kinase kinase 2 (CaMKK2) in the ovarian tumor microenvironment (250)

Abstract

Objectives: Calcium/calmodulin-dependent protein Kinase Kinase 2 (CaMKK2) has been found to be selectively expressed in cancer and immune cells of solid malignancies. Previous work has shown that high expression of CaMKK2 in ovarian cancer is associated with worse survival. Therefore, the goal of this study was to determine the effect of STO-609, a CaMKK2 inhibitor, on the immune response. Methods: Ascites from ovarian cancer patients were cultured with and without STO-609. T cell markers of activation and exhaustion were measured using flow cytometry on a BD LSRFortessa™ Cell Analyzer. Orthotopic and syngeneic murine models of ovarian cancer were utilized to determine the biologic and immunologic effects of CaMKK2 inhibition in vivo. Results: Following a seven-day culture with STO-609, we observed a decrease in co-expression of PD-1 with additional markers of T cell exhaustion (TIGIT, LAG3, and TIM3). In CD4+ T cells, the differences in average frequencies of TIGIT+, LAG3+, and TIM3+ were -4.87 (p=0.23), -3.16 (p=0.33) and -6 (p=0.23), respectively. In CD8+ T cells, the differences in average frequencies of TIGIT+, LAG3+, and TIM3+ were -7.99 (p=0.18), -0.99 (p=0.20), and -4.64 (p=0.28), respectively (Figure 1). Pharmacologic inhibition of CaMMK2 alone and with chemotherapy (cisplatin or paclitaxel) did not significantly decrease tumor growth and metastases in murine models of ovarian cancer (SKOV3ip1 and IG10). In a murine model (ID8), treated with and without STO-609 followed by checkpoint blockade, there was no significant difference in markers of T cell activation, function, or exhaustion. Objectives: Calcium/calmodulin-dependent protein Kinase Kinase 2 (CaMKK2) has been found to be selectively expressed in cancer and immune cells of solid malignancies. Previous work has shown that high expression of CaMKK2 in ovarian cancer is associated with worse survival. Therefore, the goal of this study was to determine the effect of STO-609, a CaMKK2 inhibitor, on the immune response. Methods: Ascites from ovarian cancer patients were cultured with and without STO-609. T cell markers of activation and exhaustion were measured using flow cytometry on a BD LSRFortessa™ Cell Analyzer. Orthotopic and syngeneic murine models of ovarian cancer were utilized to determine the biologic and immunologic effects of CaMKK2 inhibition in vivo. Results: Following a seven-day culture with STO-609, we observed a decrease in co-expression of PD-1 with additional markers of T cell exhaustion (TIGIT, LAG3, and TIM3). In CD4+ T cells, the differences in average frequencies of TIGIT+, LAG3+, and TIM3+ were -4.87 (p=0.23), -3.16 (p=0.33) and -6 (p=0.23), respectively. In CD8+ T cells, the differences in average frequencies of TIGIT+, LAG3+, and TIM3+ were -7.99 (p=0.18), -0.99 (p=0.20), and -4.64 (p=0.28), respectively (Figure 1). Pharmacologic inhibition of CaMMK2 alone and with chemotherapy (cisplatin or paclitaxel) did not significantly decrease tumor growth and metastases in murine models of ovarian cancer (SKOV3ip1 and IG10). In a murine model (ID8), treated with and without STO-609 followed by checkpoint blockade, there was no significant difference in markers of T cell activation, function, or exhaustion.