Abstract 1475: Local immune activation resulting in tumor growth inhibition with MEDI9197 - an intratumorally administered TLR7/8 agonist

MEDI9197 (formerly 3M-052) is a sustained-release imidazoquinoline toll like receptor (TLR) TLR7/8 agonist designed with a lipid tail that, when injected, is retained within the tumor. This has been shown in pharmacokinetic studies in mice and rats injected with MEDI9197 via the subcutaneous (SC) or intratumoral (IT, mouse only) routes. Stimulation of TLR7 and TLR8 in primary human dendritic cells induces the release of interferon-alpha (IFN-a) from plasmacytoid dendritic cells (pDCs) and interleukin 12 (IL-12) from myeloid dendritic cells (mDCs). Intratumoral administration of MEDI9197 induces a local immune response characterized by upregulation of genes involved in activation of innate and adaptive immunity both from the injected tumor and tumor draining lymph node. Furthermore, flow cytometric analysis of tumor infiltrating lymphocytes (TILs) show increased expression of activation markers, such as CD69, on natural killer (NK) cells and CD8 cytotoxic T cells. This local stimulation of immune cells with MEDI9197 results in tumor growth inhibition as shown in the B16F10 luc syngeneic mouse tumor model using in vivo imaging system (IVIS) equipment. Additionally, combination of MEDI9197 with immune checkpoint inhibitors enhances the efficacy observed in syngeneic mouse tumor models. The data presented shows intratumoral administration of MEDI9197 induces local immune activation leading to tumor growth inhibition in preclinical models of cancer. MEDI9197 is currently being evaluated as a monotherapy for safety and efficacy in human clinical trials. Citation Format: Stefanie Mullins, Iwen Grigsby, Lester I. Harrison, Song Ren, Serguei Soukharev, Lesley Young, James M. Elvecrog, Robert W. Wilkinson, Mark A. Tomai, Ronald Herbst, John P. Vasilakos, Andrew J. Leishman. Local immune activation resulting in tumor growth inhibition with MEDI9197 - an intratumorally administered TLR7/8 agonist. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1475.