Low-Dose Radiotherapy Reverses Tumor Immune Desertification and Resistance to Immunotherapy
Fernanda G Herrera, Catherine Ronet, Maria Ochoa de Olza, David Barras, Isaac Crespo, Massimo Andreatta, Jesus Corria-Osorio, Aodrenn Spill, Fabrizio Benedetti, Raphael Genolet, Angela Orcurto, Martina Imbimbo, Eleonora Ghisoni, Blanca Navarro Rodrigo, Dominik R Berthold, Apostolos Sarivalasis, Khalil Zaman, Rafael Duran, Clarisse Dromain, John Prior, Niklaus Schaefer, Jean Bourhis, Georgia Dimopoulou, Zoi Tsourti, Marius Messemaker, Thomas Smith, Sarah E Warren, Periklis Foukas, Sylvie Rusakiewicz, Mikaël J Pittet, Stefan Zimmermann, Christine Sempoux, Urania Dafni, Alexandre Harari, Lana E Kandalaft, Santiago J Carmona, Denarda Dangaj Laniti, Melita Irving, George Coukos, Fernanda G Herrera, Catherine Ronet, Maria Ochoa de Olza, David Barras, Isaac Crespo, Massimo Andreatta, Jesus Corria-Osorio, Aodrenn Spill, Fabrizio Benedetti, Raphael Genolet, Angela Orcurto, Martina Imbimbo, Eleonora Ghisoni, Blanca Navarro Rodrigo, Dominik R Berthold, Apostolos Sarivalasis, Khalil Zaman, Rafael Duran, Clarisse Dromain, John Prior, Niklaus Schaefer, Jean Bourhis, Georgia Dimopoulou, Zoi Tsourti, Marius Messemaker, Thomas Smith, Sarah E Warren, Periklis Foukas, Sylvie Rusakiewicz, Mikaël J Pittet, Stefan Zimmermann, Christine Sempoux, Urania Dafni, Alexandre Harari, Lana E Kandalaft, Santiago J Carmona, Denarda Dangaj Laniti, Melita Irving, George Coukos
Abstract
Developing strategies to inflame tumors is critical for increasing response to immunotherapy. Here, we report that low-dose radiotherapy (LDRT) of murine tumors promotes T-cell infiltration and enables responsiveness to combinatorial immunotherapy in an IFN-dependent manner. Treatment efficacy relied upon mobilizing both adaptive and innate immunity and depended on both cytotoxic CD4+ and CD8+ T cells. LDRT elicited predominantly CD4+ cells with features of exhausted effector cytotoxic cells, with a subset expressing NKG2D and exhibiting proliferative capacity, as well as a unique subset of activated dendritic cells expressing the NKG2D ligand RAE1. We translated these findings to a phase I clinical trial administering LDRT, low-dose cyclophosphamide, and immune checkpoint blockade to patients with immune-desert tumors. In responsive patients, the combinatorial treatment triggered T-cell infiltration, predominantly of CD4+ cells with Th1 signatures. Our data support the rational combination of LDRT with immunotherapy for effectively treating low T cell-infiltrated tumors. SIGNIFICANCE: Low-dose radiation reprogrammed the tumor microenvironment of tumors with scarce immune infiltration and together with immunotherapy induced simultaneous mobilization of innate and adaptive immunity, predominantly CD4+ effector T cells, to achieve tumor control dependent on NKG2D. The combination induced important responses in patients with metastatic immune-cold tumors.This article is highlighted in the In This Issue feature, p. 1.
©2021 The Authors; Published by the American Association for Cancer Research.
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