Immune-stimulating antibody conjugates elicit robust myeloid activation and durable antitumor immunity

Nat Cancer. 2021 Jan;2(1):18-33. doi: 10.1038/s43018-020-00136-x. Epub 2020 Dec 7.

Abstract

Innate pattern recognition receptor agonists, including Toll-like receptors (TLRs), alter the tumor microenvironment and prime adaptive antitumor immunity. However, TLR agonists present toxicities associated with widespread immune activation after systemic administration. To design a TLR-based therapeutic suitable for systemic delivery and capable of safely eliciting tumor-targeted responses, we developed immune-stimulating antibody conjugates (ISACs) comprising a TLR7/8 dual agonist conjugated to tumor-targeting antibodies. Systemically administered human epidermal growth factor receptor 2 (HER2)-targeted ISACs were well tolerated and triggered a localized immune response in the tumor microenvironment that resulted in tumor clearance and immunological memory. Mechanistically, ISACs required tumor antigen recognition, Fcγ-receptor-dependent phagocytosis and TLR-mediated activation to drive tumor killing by myeloid cells and subsequent T-cell-mediated antitumor immunity. ISAC-mediated immunological memory was not limited to the HER2 ISAC target antigen since ISAC-treated mice were protected from rechallenge with the HER2- parental tumor. These results provide a strong rationale for the clinical development of ISACs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptive Immunity
  • Animals
  • Antigens, Neoplasm
  • Immunotherapy* / methods
  • Mice
  • Neoplasms* / drug therapy
  • Tumor Microenvironment

Substances

  • Antigens, Neoplasm