RIG-I-targeted immunotherapy synergizes with immune checkpoint inhibition in a hepatocellular carcinoma model
(1) Marx C (2) Teppert J (3) Marisch L (4) Formisano S (5) Senz A (6) Boehmer DFR (7) Metzger P (8) Kechur D (9) Delius L (10) Hoerth C (11) Lauber K (12) Mayr D (13) De Toni EN (14) Helms MW (15) Brunner B (16) Endres S (17) Schnurr M (18) Duewell P (19) Rothenfusser S (20) Koenig LM
Marx, Teppert, and Marisch et al. showed retinoic acid-inducible gene-I (RIG-I), the cytoplasmic sensor of short dsRNA with uncapped 5’-triphosphate (3p-RNA), was expressed in human HCC samples and induced by IFN-I on cell lines. 3p-RNA treatment given i.v. reduced tumor burden in murine orthotopic tumor models and induced immune memory. Therapeutic effects depended on CD4+ and CD8+ T, but not NK cells, and on tumor-intrinsic Fas expression, but not systemic intracellular RIG-I pathway signaling. Treatment with 3p-RNA upregulated PD-L1 expression on HCC cells and synergized with anti-PD-1 to improve efficacy in HCC mouse models.
Contributed by Paula Hochman
(1) Marx C (2) Teppert J (3) Marisch L (4) Formisano S (5) Senz A (6) Boehmer DFR (7) Metzger P (8) Kechur D (9) Delius L (10) Hoerth C (11) Lauber K (12) Mayr D (13) De Toni EN (14) Helms MW (15) Brunner B (16) Endres S (17) Schnurr M (18) Duewell P (19) Rothenfusser S (20) Koenig LM
Marx, Teppert, and Marisch et al. showed retinoic acid-inducible gene-I (RIG-I), the cytoplasmic sensor of short dsRNA with uncapped 5’-triphosphate (3p-RNA), was expressed in human HCC samples and induced by IFN-I on cell lines. 3p-RNA treatment given i.v. reduced tumor burden in murine orthotopic tumor models and induced immune memory. Therapeutic effects depended on CD4+ and CD8+ T, but not NK cells, and on tumor-intrinsic Fas expression, but not systemic intracellular RIG-I pathway signaling. Treatment with 3p-RNA upregulated PD-L1 expression on HCC cells and synergized with anti-PD-1 to improve efficacy in HCC mouse models.
Contributed by Paula Hochman
ABSTRACT: Retinoic acid-inducible gene-I (RIG-I) is a cytoplasmic pattern recognition receptor that senses short double-stranded RNA with uncapped 5'-triphosphate (3p-RNA). Upon activation, RIG-I induces type I interferons and proinflammatory cytokines, thereby promoting adaptive immunity. Thus, RIG-I activation is a promising approach for creating a proinflammatory tumor microenvironment. In this study, we investigated its therapeutic potential in hepatocellular carcinoma (HCC). We explored and confirmed RIG-I expression and signaling in human HCC samples and cell lines. The therapeutic potential of RIG-I activation by 3p-RNA for the treatment of HCC was investigated in vitro and in syngeneic murine orthotopic tumor models. In vivo, 3p-RNA treatment significantly reduced the tumor burden, delayed disease progression, and achieved partial complete remission of RIL-175 tumors with durable immune memory. However, no therapeutic effects were observed in the Hep-55.1C model. Tumor clearance depended on CD4⁺ and CD8⁺ T cells, but not NK cells. Additionally, 3p-RNA induced PD-L1 expression on HCC cells, enhancing their sensitivity to anti-PD-1 immune checkpoint therapy in vivo. RIG-I activation via 3p-RNA therapy shows promise as an immunotherapeutic strategy for hepatocellular carcinoma (HCC). Future investigations need to focus on tumor-intrinsic factors to understand heterogeneity between tumors and to overcome resistance mechanisms.
