RIG-I activating immunostimulatory RNA boosts the efficacy of anticancer vaccines and synergizes with immune checkpoint blockade.
EBioMedicine 2019;
41:146-155. [PMID:
30852164 PMCID:
PMC6444128 DOI:
10.1016/j.ebiom.2019.02.056]
[Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/22/2019] [Accepted: 02/26/2019] [Indexed: 12/25/2022] Open
Abstract
Background
Antibody-mediated targeting of regulatory T cell receptors such as CTLA-4 enhances antitumor immune responses against several cancer entities including malignant melanoma. Yet, therapeutic success in patients remains variable underscoring the need for novel combinatorial approaches.
Methods
Here we established a vaccination strategy that combines engagement of the nucleic acid-sensing pattern recognition receptor RIG-I, antigen and CTLA-4 blockade. We used in vitro transcribed 5′-triphosphorylated RNA (3pRNA) to therapeutically target the RIG-I pathway. We performed in vitro functional analysis in bone-marrow derived dendritic cells and investigated RIG-I-enhanced vaccines in different murine melanoma models.
Findings
We found that protein vaccination together with RIG-I ligation via 3pRNA strongly synergizes with CTLA-4 blockade to induce expansion and activation of antigen-specific CD8+ T cells that translates into potent antitumor immunity. RIG-I-induced cross-priming of cytotoxic T cells as well as antitumor immunity were dependent on the host adapter protein MAVS and type I interferon (IFN-I) signaling and were mediated by dendritic cells.
Interpretation
Overall, our data demonstrate the potency of a novel combinatorial vaccination strategy combining RIG-I-driven immunization with CTLA-4 blockade to prevent and treat experimental melanoma.
Fund
German Research Foundation (SFB 1335, SFB 1371), EMBO, Else Kröner-Fresenius-Foundation, German Cancer Aid, European Hematology Association, DKMS Foundation for Giving Life, Dres. Carl Maximilian and Carl Manfred Bayer-Foundation.
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