Abstract 34: Wee1 inhibition sensitizes tumor cells with variable antigenicity to T cell mediated lysis

Abstract

Abstract Antigen-specific elimination of tumor cells by cytotoxic T-lymphocytes (CTL) inherently relies upon the sensitivity of target cells to effector products such as granzyme B, TNFa, TNF-related apoptosis-inducing ligand (TRAIL), and Fas ligand (FasL). Cell cycle progression is critically required for granzyme B and TNF superfamily-induced apoptosis. Thus, we hypothesized that inhibition of Wee1 with AZD1775 would release the G2/M cell cycle checkpoint and enhance sensitivity of oral cavity cancer cells to CTL killing. To explore this hypothesis, we stably transduced murine oral cancer 1 (MOC1) cells with a construct encoding the fluorescent protein mKate2 and SIINFEKL, the H2-Kb-restricted epitope of ovalbumin (MOC1mK2SIIN). Using in-vitro generated SIINFEKL-specific OT-1 CTLs as effectors, we demonstrated in a real-time, impedance-based assay of cytotoxicity that physiologic concentrations of AZD1775 (250 nM) significantly sensitized MOC1mK2SIIN cells to CTL killing at low E:T ratios. The same concentration of AZD1775 had negligible effects on the MOC1mK2SIIN cells alone, and OT-1 CTL cytotoxicity was antigen-specific as OT-1 effectors did not kill parental MOC1 cells with or without AZD1775 treatment. This effect was partially reversed with the perforin inhibitor concanamycin A, implicating involvement of granzyme B. Further, by mixing MOC1mK2SIIN and parental MOC1 cells, we could alter the ratio of antigen clonality present within the target cell population. Inhibition of Wee1 with AZD1775 significantly enhanced OT-1 CTL control of target cell populations where 5, 10, 15, 20, 25, and 50% lack SIINFEKL antigen. Treatment of MOC1mK2SIIN and parental MOC1 cells with recombinant TNFa, TRAIL and FasL with and without AZD1775 confirmed enhanced TNF superfamily-induced tumor cell control following Wee1 inhibition. These data suggest that Wee1 inhibition broadly sensitizes antigen positive and negative cells to CTL effector products and that AZD1775 may induce “bystander killing” of antigen negative cells in target cell populations with mixed antigenicity. Experiments combining AZD1775 with immune-activating therapies in vivo are underway. Citation Format: Ellen Moore, Lillian Sun, Jay Friedman, Carter Van Waes, Clint Allen. Wee1 inhibition sensitizes tumor cells with variable antigenicity to T cell mediated lysis [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; April 23-25, 2017; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(23_Suppl):Abstract nr 34.