60systemically administered oncolytic vaccinia virus enhances the in vivo antitumor effects of rtki and anti-pd-1 based therapies in an immunocompetent renal cancer model

Background While significant advances have been made in the treatment of metastatic renal cell carcinoma (RCC), most patients develop treatment resistance and succumb to progressive disease. Limited options exist for patients checkpoint inhibitor (CPI) and/or receptor tyrosine kinase inhibitor (RTKI) based therapies, underscoring the urgent need to develop novel strategies for RCC. The oncolytic vaccinia virus (VV) is a promising antitumor agent undergoing clinical development in RCC and other cancers. The objectives of this study are to characterize the in vivo effects and mechanisms of oncolytic VV in combination with RTKIs and checkpoint inhibitors in RCC. Methods The oncolytic effects of VV expressing human (JX-594) or murine (mJX-594) GMCSF, on human and murine renal cancer cell lines were assessed (xCELLigence). The effects of VV on human RCC hypoxia, metabolism, and survival pathways were assessed by RPPA analysis. The effects of mJX-594 on the tumor immune microenvironment were investigated in the immunocompetent RENCA murine model through transcriptomic analyses and imaging mass cytometry to delineate immune cell infiltration and gene expression signatures. The effects of VV in combination with the RTKI Cabozantinib (C) on viral oncolysis and replication were determined. The in vivo anti-tumor effects of mJX-594, Cabozantinib and anti-PD-1 antibodies alone and in combination (doublets vs. triplet) were determined in the RENCA model. Tumor correlative studies were performed to characterize the mechanisms of VV-Cabozantinib-anti-PD-1 combinations. Results Potent in vitro oncolysis and efficient viral replication were observed in human and murine RCC cells after VV infection. Viral oncolysis was associated with significant modulation of metabolism, survival and hypoxia pathways. Mass cytometry analysis showed a significant increase in immune cell infiltrates, especially neutrophils, after VV treatment. NanoString gene expression data confirmed VV-induced regulation of immune pathways, with strong increases in neutrophils, T cells, and cytotoxic T cells. In vitro, Cabozantinib did not interfere with vaccinia viral replication or with viral oncolysis in human or murine RCC cell lines. In vivo, while Cabozantinib, and treatment doublets had enhanced antitumor activity compared to single agents, the mJX-594, Cabozantinib and anti-PD-1 antibody combination was associated with more profound and prolonged antitumor activity and survival. Correlative tumor studies showed enhanced VV tumor penetration by Cabozantinib, decreased tumor angiogenesis and enhanced apoptosis by VV. Conclusions This is the first report demonstrating that the oncolytic VV significantly enhances the in vivo antitumor effects of RTKI+CPI combination therapy in an immunocompetent renal cancer model. The non-overlapping mechanisms of VV oncolysis, as well as cabozantinib enhancement of VV tumor penetration, leading to enhanced apoptosis may explain the effects of the virus-drug combination. The superiority of the triplet compared to doublets (C+VV or C+anti-PD-1) suggests that oncolytic viruses, in particular oncolytic VV can synergize with current anti-RCC therapies.