ET-70 * COMBINATION OF oHSV WITH INTEGRIN 1 NEUTRALIZING ANTIBODY (OS2966) AUGMENTS oHSV THERAPY

Abstract

Oncolytic HSV (oHSV) is a biologic therapy currently being tested in patients. We have previously shown that oHSV-induced Cysteine-rich 61 protein (CCN1) binds with integrin α6β1, activating a type 1 IFN-antiviral defense response. oHSV-induced CCN1 induction also increases macrophage infiltration and activation, resulting in increased virus clearance in glioblastoma cells. Integrin β1 is cell surface molecule involved in multiple functions like cellular proliferation, invasion and inflammation. Inhibition of integrin β1 has shown anti-tumor efficacy in preclinical modles of glioma. Furthermore, incorporating the Rembrandt database of the National Cancer Institute, we found integrin β1 expression is negatively associated with glioblastoma patient survival (p value < 0.0001). Interestingly, oHSV infection strongly increased integrin β1 expression (western blot). Based on this, we hypothesized that the combination of oHSV with integrin β1neutralizing antibody (OS2966) will augment oHSV therapy. Combination treatment with OS2966 increased oHSV replication and cell killing. Increased viral replication and cell killing was more obvious in the laminin-coated cells, consistent with integrin β1 signaling pathway. OS2966 treatment strongly inhibited oHSV-induced raw246.7 macrophage cell migration towards infected glioblastoma cells as dose dependent manner (migration assay). Inhibition of integrin β1in glioma cell lines and patient derived primary GSCs significantly increased markers of sensencsence such as enhanced β-gal activity, along with induction of p21, and reduction of phosphorylation of AKT and Rb, indicating that integrin β1 activation is involved in self-renewal, and proliferation. In conclusion, oHSV-induced integrin β1 expression sensitize to OS2966 effect, resulting in enhanced viral replication and inhibition of macrophage migration. Our findings reveal how integrin β1 limits oHSV replication. Our findings also reveal how OS2966, an integrin β1 blocking antibody which has been humanized in anticipation of potential clinical trials, inhibits the innate immune response elicited upon oHSV therapy. The results will lead to the development of a novel oHSV therapeutic strategy.