Abstract 4885: Intratumoral injection of G100 (TLR4 agonist glycopyranosyl lipid A) modulates tumor microenvironment and induces CD8 T cell-dependent, systemic anti-tumor immunity

Abstract

Abstract The tumor microenvironment (TME) plays a critical role in controlling the balance between tumor progression and immune surveillance. Increased infiltration of T cells, especially CD8 T cells has been associated with a good prognosis. We hypothesized that G100, a novel synthetic TLR4 agonist, can modulate TME when directly injected into the tumor and trigger both a local and systemic effective immune response. Balb/c mice with implanted syngeneic A20 lymphoma received intratumoral (IT) injection of G100 (10 ìg) or control PBS three times a week. This treatment significantly inhibited tumor growth and resulted in complete tumor regression in approximately 60% of treated mice. To investigate the effects of G100 on TME, tumors were collected after three IT G100 injections for gene expression analysis by Nanostring and immune phenotyping analysis by FACS. Out of the 770 immune response genes included in the mouse PanCancer Immune Profiling panel, 295 genes were significantly upregulated in G100 treated tumors. The upregulated genes include DC function-related genes (CD40, CD83, CD86, and Ly96) and T cell and NK cell function genes and multiple chemokines and cytokines (IL1b, IL12A, IL18, IL6, IFNã, FcãR4, ICOS, GZMB, CCL3, CCL5, CCL7, CXCL1, CXCL2, CXCL11, CCR5, CCR6, and CCR7). T cell exhaustion markers (CTLA4 and LAG3) and CD274 (PD-L1) were also induced. G100-induced inflammation is also reflected at the cellular level as shown by increased T cells and NK cells in tumor via FACS analysis. To determine the immune cells that mediated tumor rejection, mice were selectively depleted of CD4 or CD8 T cells during G100 treatment. Results showed that the anti-tumor effect of G100 is dependent on CD8 T cells. G100-induced tumor protection was durable as mice surviving the first tumor challenge rejected a secondary tumor challenge without additional G100 treatment. Altogether, our results showed that IT G100 induces a proinflammatory cytokine and chemokine milieu that changes a “cold” tumor to a “hot” tumor, which facilitates the development of a CD8 T cell-dependent potent and durable anti-tumor effect. The induction of PD-L1 also suggests the potential synergy between G100 and checkpoint blockade therapy. These preclinical data support an on-going clinical trial of IT G100 in patients with follicular non-Hodgkin's lymphoma (NCT02501473), alone and in combination with anti-PD-1 therapy (pembrolizumab). Citation Format: Hailing Lu, Jessica Hewitt, Jan ter Meulen. Intratumoral injection of G100 (TLR4 agonist glycopyranosyl lipid A) modulates tumor microenvironment and induces CD8 T cell-dependent, systemic anti-tumor immunity. [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 4885.