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Preliminary Results From A First-In-Human Phase 1 Study Of The Cd40 Agonist Monoclonal Antibody (Mab) Cdx-1140, Rachel Sanborn, Michael S. Gordon, Mark O'Hara, Nina Bhardwaj, Yi He, Tracey Rawls, Tibor Keler, Michael Yellin

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Agonist CD40 mAbs can mediate antitumor immunity through multiple mechanisms, including enhancing tumor antigen presentation, activation of tumoricidal macrophages, and direct growth inhibition/killing of CD40- expressing tumor cells. To fully exploit these mechanisms may require the mAb to be dosed at levels that provide significant tumor and tissue penetration, without dose-limiting-toxicities (DLT) from systemic CD40 activation. Our agonist CD40 mAb, CDX-1140, was selected based on its unique and linear dose-dependent in vitro and in vivo activity and is postulated will achieve maximum agonist activity at dose levels associated with good systemic exposure. CDX-1140 is a fully human IgG2 agonist …

Mv-626, A Potent And Selective Inhibitor Of Enpp1 Enhances Sting Activation And Augments T-Cell Mediated Anti-Tumor Activity In Vivo, Jason Baird, Gregory Dietsch, Vincent Florio, Michael Gallatin, Clayton Knox, Joshua Odingo, Marka Crittenden, Michael J. Gough

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: STING is an endogenous sensor of cGAMP, which is synthesized by cGAS following detection of cytoplasmic DNA. STING activation leads to interferon production and activation of inflammatory pathways that facilitate cytolytic T cell priming. STING agonists administered intratumorally show potent anti-tumor efficacy in a range of preclinical models; several agonists are in clinical development. Radiation therapy also increases cytoplasmic DNA levels in cancer cells, resulting in STING activation and secretion of inflammatory cytokines. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is the phosphodiesterase that negatively regulates STING by hydrolyzing cGAMP. MV-626, a highly potent and selective ENPP1 inhibitor with 100% oral bioavailability …

Inducible T Cell Co-Stimulator (Icos) Is Upregulated On Lymphocytes Following Radiation Of Tumors And Icos Agonism In Combination With Radiation Results In Enhanced Tumor Control, Michael J. Gough, Shelly Bambina, Monica Gostissa, Christopher Harvey, David Friedman, Marka R Crittenden

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Radiation and co-stimulatory ligands or checkpoint inhibitors have demonstrated improved anti-tumor immunity and overall survival in preclinical animal studies. However, the results of human trials suggest we have not yet found the optimal combination. Here we demonstrate upregulation of ICOS expression on T cells following focal tumor radiation and test the hypothesis that ICOS agonism in combination with radiation will enhance the immunologic effect of radiation resulting in increased survival.

Methods: BALB/c mice bearing CT26 tumors or C57BL/6 mice bearing Panc02 tumors were treated at d14 with 20Gy CT guided radiation therapy and anti-ICOS antibody or isotype control antibody …

Pegzilarginase In Combination With Agonist Anti-Ox40 Therapy Enhances T Cell Priming And Effector Function Leading To Improved Tumor Regression And Survival, Melissa Kasiewicz, Annah Rolig, Elizabeth Sturgill, Mark Badeaux, Scott Rowlinson, William L. Redmond

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Tumor cells defective in enzymes required for arginine biosynthesis are dependent upon arginine uptake from the environment. Extracellular depletion of arginine directly affects tumor cells, inducing autophagy and apoptosis. Pegzilarginase (AEB1102) is a bioengineered, pegylated, human arginase 1 (Aeglea Biotherapeutics) currently in phase I clinical trials. This arginine-depleting agent has been shown to both inhibit arginine auxotrophic tumor growth and to enhance the efficacy of PD-L1 blockade in preclinical models. In the current study, we investigated the therapeutic efficacy and mechanism of action of combined pegzilarginase/anti-OX40 (aOX40) immunotherapy. We hypothesized that pegzilarginase/aOX40 treatment would synergize to enhance T cell …

Combined Anti-Pd-1 And Anti-Lag-3 Checkpoint Blockade Enhances Cd8+ Til Effector Function While Reducing Tregs Leading To Reduced Immune Suppression And Improved Overall Survival, Elizabeth Sturgill, Courtney Mick, David Jenkins, Johanna Kaufmann, William L. Redmond

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Checkpoint inhibition is a potent strategy to reinvigorate T cells. However, aCTLA-4 or aPD-1 monotherapy has not been effective for the majority of patients, resulting in the exploration of combinatorial approaches to improve treatment efficacy. One such target is LAG-3, which is upregulated on T cells that have experienced repeated antigen exposure, such as in the tumor microenvironment (TME), and is associated with reduced T cell effector function. In addition, high LAG-3 expression on regulatory T cells (Tregs) has been reported for patients with varying cancer types, providing an additional rationale for targeting LAG-3 with the aim of reducing …

Nktr-214 (Cd122-Biased Agonist) And Nktr-262 (Tlr7/8 Agonist) Combination Treatment Pairs Local Innate Immune Activation With Systemic Cd8+ T Cell Expansion To Enhance Anti-Tumor Immunity, Annah S. Rolig, Daniel Rose, Saul Kivimäe, Deborah Charych, Werner Rubas, Jonathan Zalevsky, William L. Redmond

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Radiation therapy (RT) remains the standard of care for many human cancers. Combining NKTR-214, a CD122-biased cytokine agonist conjugated with releasable polyethylene-glycol (PEG) chains, with local RT significantly enhanced therapeutic efficacy in preclinical models. Mechanistically, NKTR-214 provides sustained signaling through the IL-2 receptor pathway (IL-2Rβγ) to preferentially activate and expand effector CD8+ T and NK cells and RT modulates the tumor microenvironment (TME) to induce antigen-release. Together, NKTR-214/RT treatment resulted in improved therapeutic responses compared to either treatment alone. However, abscopal responses in murine tumors were modest, leading us to explore alternative approaches with the potential to elicit more …

Mertk Is A Therapeutic Target In Combination With Radiation To Promote Adaptive Immune Tumor Responses, Garth Tormoen, Jason R Baird, Gwen Kramer, Shelly Bambina, Marka R Crittenden, Michael J. Gough

Society for Immunotherapy of Cancer 2018 Annual Meeting Posters

Background: Mertk is a member of the Tyro3-Axl-Mertk (TAM) family of receptors and regulates phagocytosis of dying cells by macrophages. Cancer cells killed by radiation therapy direct repolarization of macrophages into immune suppressive phenotypes. Mertk-/- mice grafted with immunogenic tumors have enhanced tumor control following ionizing radiation compared to Mertkwt mice. Gas6 is the endogenous ligand for Mertk and its ability to signal through Mertk requires a post-translational vitamin k-dependent modification that is inhibited by warfarin.

Methods: Mertk-/- and WT mice were injected subcutaneously in the flank with 5E4 CT26 cells (BALB/c) or 5E6 Panc02-SIY cells (C57BL/6) and allowed to …