Research ArticleCancer

Intratumoral expression of IL-7 and IL-12 using an oncolytic virus increases systemic sensitivity to immune checkpoint blockade

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Science Translational Medicine  15 Jan 2020:
Vol. 12, Issue 526, eaax7992
DOI: 10.1126/scitranslmed.aax7992

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A virus with benefits

Oncolytic viruses, which kill cancer cells, have received increasing attention in recent years as the field has advanced toward biological and immune-based approaches to fighting cancer. To help further these viruses’ cancer-fighting potential, Nakao et al. engineered an oncolytic vaccinia virus to deliver two cytokines that help stimulate antitumor immune responses. The authors successfully tested this approach in multiple immunocompetent mouse models, showing promising results in directly treated tumors and in distant tumors of the same type, as well as protection from rechallenge with tumor cells. The treatment was particularly effective in combination with immune checkpoint inhibitors, even in tumors unresponsive to checkpoint inhibitors alone.

Abstract

The immune status of the tumor microenvironment is a key indicator in determining the antitumor effectiveness of immunotherapies. Data support the role of activation and expansion of tumor-infiltrating lymphocytes (TILs) in increasing the benefit of immunotherapies in patients with solid tumors. We found that intratumoral injection of a tumor-selective oncolytic vaccinia virus encoding interleukin-7 (IL-7) and IL-12 into tumor-bearing immunocompetent mice activated the inflammatory immune status of previously poorly immunogenic tumors and resulted in complete tumor regression, even in distant tumor deposits. Mice achieving complete tumor regression resisted rechallenge with the same tumor cells, suggesting establishment of long-term tumor-specific immune memory. Combining this virotherapy with anti–programmed cell death-1 (PD-1) or anti–cytotoxic T lymphocyte antigen 4 (CTLA4) antibody further increased the antitumor activity as compared to virotherapy alone, in tumor models unresponsive to either of the checkpoint inhibitor monotherapies. These findings suggest that administration of an oncolytic vaccinia virus carrying genes encoding for IL-7 and IL-12 has antitumor activity in both directly injected and distant noninjected tumors through immune status changes rendering tumors sensitive to immune checkpoint blockade. The benefit of intratumoral IL-7 and IL-12 expression was also observed in humanized mice bearing human cancer cells. These data support further investigation in patients with non-inflamed solid tumors.

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