Intravenous administration of the selective toll-like receptor 7 agonist DSR-29133 leads to anti-tumor efficacy in murine solid tumor models which can be potentiated by combination with fractionated radiotherapy.

Simon J Dovedi, Amy Adlard, Yosuke Ota, Masashi Murata, Eiji Sugaru, Erina Koga-Yamakawa, Ken Eguchi, Yuko Hirose, Setsuko Yamamoto, Hiroki Umehara, Jamie Honeychurch, Eleanor J Cheadle, Gareth Hughes, Philip J Jewsbury, Robert W Wilkinson, Ian Stratford, Timothy M Illidge

Research output: Contribution to journalArticlepeer-review

Abstract

Strategies to augment anti-cancer immune responses have recently demonstrated therapeutic utility. To date clinical success has been achieved through targeting co-inhibitory checkpoints such as CTLA-4, PD-1, and PD-L1. However, approaches that target co-activatory pathways are also being actively being developed. Here we report that the novel TLR7-selective agonist DSR-29133 is well tolerated in mice and leads to acute immune activation. Administration of DSR-29133 leads to the induction of IFNα/γ, IP-10, TNFα, IL-1Ra and IL-12p70, and to a reduction in tumor burden in syngeneic models of renal cancer (Renca), metastatic osteosarcoma (LM8) and colorectal cancer (CT26). Moreover, we show that the efficacy of DSR-29133 was significantly improved when administered in combination with low-dose fractionated radiotherapy (RT). Effective combination therapy required weekly administration of DSR-29133 commencing on day 1 of a fractionated RT treatment cycle, whereas no enhancement of radiation response was observed when DSR-29133 was administered at the end of the fractionated RT cycle. Combined therapy resulted in curative responses in a high proportion of mice bearing established CT26 tumors which was dependent on the activity of CD8+ T-cells but independent of CD4+ T-cells and NK/NKT cells. Moreover, long-term surviving mice originally treated with DSR-29133 and RT were protected by a tumor-specific memory immune response which could prevent tumor growth upon rechallenge. These results demonstrate that DSR-29133 is a potent selective TLR7 agonist that when administered intravenously can induce anti-tumor immune responses that can be further enhanced through combination with low-dose fractionated RT.
Original languageEnglish
Pages (from-to)17035-17046
JournalOncotarget
Volume7
DOIs
Publication statusPublished - 5 Mar 2016

Keywords

  • TLR7
  • immunotherapy
  • radiation
  • radiotherapy
  • toll-like receptor

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