Abstract 710: CD73 inhibitors (CD73i) reverse the AMP/adenosine-mediated impairment of immune effector cell activation by immune checkpoint inhibitors (ICI)

Abstract

INTRODUCTION: CD73 catalyzes the extracellular generation of adenosine (ADO) from adenosine monophosphate (AMP). ADO suppresses immune responses, including those of T cells, NK cells and dendritic cells through activation of A2aR and A2bR receptors. Exhausted T cells and NK cells express high levels of several immune checkpoint proteins, including PD-1 and TIGIT. We present here preclinical data on the ability of CD73i to reverse effector cell suppression from exposure to ADO even in the presence of ICI. METHODS: CD73i effects in a monotherapeutic setting were assessed by CD3/CD28/CD2 T cell stimulation and cytolytic assays. Combinatorial settings were assessed using mixed lymphocyte reactions (MLRs). In vivo effects of CD73i + ICI were determined using syngeneic tumor models. RESULTS: CD73 is expressed across a wide range of tumor types, including those with limited response to anti-PD-1 therapy. CD73i completely rescued AMP-mediated inhibition of T cell proliferation and effector function as well as NK cell cytolytic function. AMP abrogated the enhanced allogeneic CD4+ T cell activation and IFN-γ production mediated by blocking PD-1/PD-L1 and TIGIT, an effect that was reversed by CD73i. Mechanistically, addition of AMP in MLRs repressed expression of activation markers and immune checkpoint proteins. Thus, activation of the adenosinergic pathway may limit the efficacy of ICI. TCGA data from anti-PD-1-treated melanoma patients identified CD73 expression as a negative prognostic factor. Finally, co-administration of a CD73i with an anti-PD-1 mAb resulted in significant reduction of tumor volume associated with increases in immune cell infiltration. CONCLUSIONS: CD73 inhibition, alone or in combination with anti-PD-1 and anti-TIGIT antibodies, translates into potent enhancement of immune cell activation in a variety of studies. These data provide a rationale for CD73i + ICI combinations. Citation Format: Annette Becker, Nell Narasappa, Fangfang Yin, Kristen Zhang, Daniel DiRenzo, Timothy Park, Jaroslaw Kalisiak, Ken Lawson, Jenna Jeffrey, Jay P. Powers, Ulrike Schindler, Matthew J. Walters, Joanne B. Tan. CD73 inhibitors (CD73i) reverse the AMP/adenosine-mediated impairment of immune effector cell activation by immune checkpoint inhibitors (ICI) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 710.

Cd73: An Emerging Checkpoint for Cancer Immunotherapy

“…Arcus Biosciences have discovered AB680, a highly potent, reversible and selective inhibitor of CD73, with a favorable projected human PK profile suitable for parental administration [142]. Moreover, coadministration of AB680 with an anti-PD-1 mAb, results in a significant reduction of tumor growth associated with increased tumor-infiltrating immune cells [143]. According to a recent global immuno-oncology landscape survey in September 2018 [144], there are 16 active reagents targeting CD73 currently under development.…”

Targeting Metabolism of Extracellular Nucleotides via Inhibition of Ectonucleotidases CD73 and CD39

“…In 2018, Arcus Biosciences presented posters at the AACR Annual Meeting and the CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, which described the ability of AB680 to enhance antitumor immunity. , To assess the ability of AB680 to reverse adenosine-mediated immune suppression on human CD4 + and CD8 + T cells, AB680 was evaluated both as a monotherapy and in combination with immune checkpoint inhibition using T cell stimulation and cytolytic assays, as well as mixed lymphocyte reactions (MLRs). , In human CD4 + T cells, adenosine signaling through A 2A R inhibits cell proliferation and reduces the production of cytokines, such as interleukin-2 (IL-2) and IFN-γ. For these studies, activation of human CD4 + T cells was accomplished using anti-CD3/CD28/CD2 antibodies and IL-2, and IFN-γ production was quantified using cytokine bead arrays.…”

“…For these studies, activation of human CD4 + T cells was accomplished using anti-CD3/CD28/CD2 antibodies and IL-2, and IFN-γ production was quantified using cytokine bead arrays. In the absence of AMP, strong CD4 + T cell activation could be accomplished and manifested in a high percentage of proliferating cells (Figure a) and cytokine production (Figure b,c). , To simulate adenosine-mediated immune suppression, the combination of AMP (6.25 μM) and an adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)­adenine) (EHNA, 2.5 μM), was added to the cell cultures during activation, resulting in marked suppression of proliferation and cytokine production. Addition of exogenous AB680 completely restored CD4 + T cell proliferation and cytokine production in a dose-dependent manner, and a similar effect was observed on CD8 + T cell activation (Figure d) …”

“…AB680 restores the proliferation and function of CD4 + T-cells (a–c), restores the activation of CD8 + T-cells (d), and reverses the activity of AMP on immune checkpoint inhibition in MLRs (e). , Charts a–e are reproduced from refs and .…”

“…This Perspective will focus primarily on recent drug discovery efforts targeting CD73-mediated adenosine production. Given that CD73 catalyzes the final step in the production of extracellular adenosine, inhibition of CD73 represents a promising approach to decreasing adenosine levels and potentially restoring antitumor immunity. − Indeed, various preclinical studies have shown that CD73 inhibition in vivo limits the growth and metastasis of tumor cells, increases cytokine secretion, and enhances the antitumor effects of therapies targeting programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). − Furthermore, increased levels of CD73 have been associated with poor prognosis in lung, ovarian, and prostate cancer patients − and have also been observed in tumors that were resistant to treatment with chemotherapy. − Taken together, these observations provide strong biological rationale for targeting CD73 in immuno-oncology (IO) and have led to increased efforts across the biopharmaceutical industry to develop CD73 inhibitors.…”