Intratumoral IL12 mRNA Therapy Promotes TH1 Transformation of the Tumor Microenvironment

Clin Cancer Res. 2020 Dec 1;26(23):6284-6298. doi: 10.1158/1078-0432.CCR-20-0472. Epub 2020 Aug 17.

Abstract

Purpose: While immune checkpoint inhibitors such as anti-PD-L1 are rapidly becoming the standard of care in the treatment of many cancers, only a subset of treated patients have long-term responses. IL12 promotes antitumor immunity in mouse models; however, systemic recombinant IL12 had significant toxicity and limited efficacy in early clinical trials.

Experimental design: We therefore designed a novel intratumoral IL12 mRNA therapy to promote local IL12 tumor production while mitigating systemic effects.

Results: A single intratumoral dose of mouse (m)IL12 mRNA induced IFNγ and CD8+ T-cell-dependent tumor regression in multiple syngeneic mouse models, and animals with a complete response demonstrated immunity to rechallenge. Antitumor activity of mIL12 mRNA did not require NK and NKT cells. mIL12 mRNA antitumor activity correlated with TH1 tumor microenvironment (TME) transformation. In a PD-L1 blockade monotherapy-resistant model, antitumor immunity induced by mIL12 mRNA was enhanced by anti-PD-L1. mIL12 mRNA also drove regression of uninjected distal lesions, and anti-PD-L1 potentiated this response. Importantly, intratumoral delivery of mRNA encoding membrane-tethered mIL12 also drove rejection of uninjected lesions with very limited circulating IL12p70, supporting the hypothesis that local IL12 could induce a systemic antitumor immune response against distal lesions. Furthermore, in ex vivo patient tumor slice cultures, human IL12 mRNA (MEDI1191) induced dose-dependent IL12 production, downstream IFNγ expression and TH1 gene expression.

Conclusions: These data demonstrate the potential for intratumorally delivered IL12 mRNA to promote TH1 TME transformation and robust antitumor immunity.See related commentary by Cirella et al., p. 6080.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Apoptosis
  • B7-H1 Antigen / antagonists & inhibitors
  • CD8-Positive T-Lymphocytes
  • Cell Proliferation
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / immunology
  • Colorectal Neoplasms / pathology
  • Colorectal Neoplasms / prevention & control*
  • Drug Resistance, Neoplasm
  • Female
  • Humans
  • Interleukin-12 / administration & dosage*
  • Interleukin-12 / genetics
  • Lymphocytes, Tumor-Infiltrating / immunology*
  • Melanoma / genetics
  • Melanoma / immunology
  • Melanoma / pathology
  • Melanoma / prevention & control*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Nude
  • Mice, SCID
  • RNA, Messenger / administration & dosage*
  • RNA, Messenger / genetics
  • Th1 Cells / immunology*
  • Tumor Cells, Cultured
  • Tumor Microenvironment / immunology*
  • Xenograft Model Antitumor Assays

Substances

  • Antibodies, Monoclonal
  • B7-H1 Antigen
  • CD274 protein, human
  • RNA, Messenger
  • Interleukin-12