Liat Dassa

The interaction of TIGIT with PVR and PVRL2 inhibits human NK cell cytotoxicity

NK cell cytotoxicity is controlled by numerous NK inhibitory and activating receptors. Most of the inhibitory receptors bind MHC class I proteins and are expressed in a variegated fashion. It was recently shown that TIGIT, a new protein expressed by T and NK cells binds to PVR and PVR-like receptors and inhibits T cell activity indirectly through the manipulation of DC activity. Here, we show that TIGIT is expressed by all human NK cells, that it binds PVR and PVRL2 but not PVRL3 and that it inhibits NK cytotoxicity directly through its ITIM. Finally, we show that TIGIT counter inhibits the NK-mediated killing of tumor cells and protects normal cells from NK-mediated cytoxicity thus providing an “alternative self” mechanism for MHC class I inhibition.

A Novel Peptide Agonist of Formyl-Peptide Receptor-Like 1 (ALX) Displays Anti-Inflammatory and Cardioprotective Effects

Activation of the formyl-peptide receptor-like (FPRL) 1 pathway has recently gained high recognition for its significance in therapy of inflammatory diseases. Agonism at FPRL1 affords a beneficial effect in animal models of acute inflammatory conditions, as well as in chronic inflammatory diseases. TIPMFVPESTSKLQKFTSWFM-amide (CGEN-855A) is a novel 21-amino acid peptide agonist for FPRL1 and also activates FPRL2. CGEN-855A was discovered using a computational platform designed to predict novel G protein-coupled receptor peptide agonists cleaved from secreted proteins by convertase proteolysis. In vivo, CGEN-855A displays anti-inflammatory activity manifested as 50% inhibition of polymorphonuclear neutrophil (PMN) recruitment to inflamed air pouch and provides protection against ischemia-reperfusion-mediated injury to the myocardium in both murine and rat models (36 and 25% reduction in infarct size, respectively). Both these activities are accompanied by inhibition of PMN recruitment to the injured organ. The secretion of inflammatory cytokines, including interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, was not affected upon incubation of human peripheral blood mononuclear cells with CGEN-855A, whereas IL-8 secretion was elevated up to 2-fold upon treatment with the highest CGEN-855A dose only. Collectively, these new data support a potential role for CGEN-855A in the treatment of reperfusion-mediated injury and in other acute and chronic inflammatory conditions.

A Novel Recombinant Soluble Splice Variant of Met Is a Potent Antagonist of the Hepatocyte Growth Factor/Scatter Factor-Met Pathway

Purpose: The Met receptor tyrosine kinase and its ligand, hepatocyte growth factor/scatter factor (HGF/SF), are involved in a wide range of biological activities, including cell proliferation, motility, invasion, and angiogenesis. The HGF/SF-Met signaling pathway is frequently activated in a variety of cancers, and uncontrolled Met activation correlates with highly invasive tumors and poor prognosis. In this study, we investigated the inhibitory effect of a novel soluble splice variant of Met on the HGF/SF-Met pathway. Experimental Design: Using our alternative splicing modeling platform LEADS, we have identified a novel splice variant of the Met receptor, which encodes a truncated soluble form of the receptor. This variant was produced as a recombinant Fc-fused protein named Cgen-241A and was tested in various cell-based assays representing different outcomes of the HGF/SF-Met pathway. Results: Cgen-241A significantly inhibited HGF/SF-induced Met phosphorylation as well as cell proliferation and survival. In addition, Cgen-241A showed a profound inhibitory effect on cell scattering, invasion, and urokinase up-regulation. The inhibitory effects of Cgen-241A were shown in multiple human and nonhuman cell types, representing different modes of Met activation. Furthermore, Cgen-241A showed direct binding to HGF/SF. Conclusions: Taken together, our results indicate that Cgen-241A is a potent antagonist of the HGF/SF-Met pathway, underlining its potential as a therapeutic agent for the treatment of a wide variety of human malignancies that are dependent on this pathway.

Identification of novel immune checkpoints as targets for cancer immunotherapy

Members of the B7/CD28 family of immune checkpoints, such as CTLA-4, PD1 and PDL-1, play critical roles in T cell regulation and have emerged as promising drug targets for cancer immunotherapy. Utilizing Compugen’s predictive discovery platform, we identified novel members of this family that may serve as immune checkpoints. The therapeutic relevance of these proteins was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Here we present results obtained for two of our novel B7/CD28 family members: CGEN-15001T and CGEN-15022. Fusion proteins, consisting of the extracellular domain of the predicted proteins fused to an IgG Fc domain, display robust inhibition of T cell activation and therapeutic effects in T-cell driven animal models, EAE and CIA. The Fc fused protein of CGEN-15001T also showed enhancement of iTregs induction. Immunohistochemistry studies on a variety of healthy and malignant tissues indicate expression of both molecules in various types of epithelial and hematopoietic cancers, with each protein showing a unique expression pattern. Expression was also detected on tumor infiltrating immune cells. Based on their immunomodulatory activity and expression in malignant and immune cells, CGEN-15001T and CGEN-15022 show potential as targets for cancer immunotherapy.

ILDR2 Is a Novel B7-like Protein That Negatively Regulates T Cell Responses

The B7-like protein family members play critical immunomodulatory roles and constitute attractive targets for the development of novel therapies for human diseases. We identified Ig-like domain–containing receptor (ILDR)2 as a novel B7-like protein with robust T cell inhibitory activity, expressed in immune cells and in immune-privileged and inflamed tissues. A fusion protein, consisting of ILDR2 extracellular domain with an Fc fragment, that binds to a putative counterpart on activated T cells showed a beneficial effect in the collagen-induced arthritis model and abrogated the production of proinflammatory cytokines and chemokines in autologous synovial-like cocultures of macrophages and cytokine-stimulated T cells. Collectively, these findings point to ILDR2 as a novel negative regulator for T cells, with potential roles in the development of immune-related diseases, including autoimmunity and cancer.

S9. Proffered paper: Identification of novel immune checkpoints as targets for cancer immunotherapy

Members of the B7/CD28 family of immune checkpoints, such as CTLA4, PD1 and PDL-1, play critical roles in T cell regulation and have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional novel members of the B7/CD28 family play a role as negative immune regulators and thus may serve as targets for therapeutic mAbs. Utilising Compugen’ sp redictive discovery platform, we identified nine novel members of this family that may serve as immune checkpoints. The therapeutic relevance of three of these proteins, CGEN-15001T, CGEN-15022, and CGEN-15049, was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Two of these proteins, CGEN-15001T and CGEN-15022, are the basis of a license and collaboration agreement recently signed with Bayer as targets for cancer immunotherapy. Here we present results obtained for an additional novel immune checkpoint, CGEN-15049. Following its ectopic expression on cancer cell lines, CGEN-15049 inhibits the activity of NK cells and cytotoxic T cells (CTLs). The fusion protein, consisting of the extracellular domain of CGEN-15049 fused to an IgG Fc domain, displays robust inhibition of T cell activation and enhances iTregs differentiation. IHC studies indicate that CGEN15049 is expressed in tumour cells of numerous types of cancers, as well as in tumour infiltrating immune cells. Based on its immunomodulatory activities on several types of immune cells which play key roles in cancer immune evasion, together with its expression pattern,CGEN-15049 may serve as mAb target for cancer immunotherapy.

Abstract 581: Discovery and development of COM701, a therapeutic antibody targeting the novel immune checkpoint PVRIG

Background: While blockade of the CTLA4 and PD1 pathways has emerged as an effective treatment of cancer, the majority of patients do not derive long term benefit. This provides a rationale for identifying and targeting additional checkpoints. Employing our unique computational algorithms, we identified PVRIG, a new member of the B7/CD28 family. We report here the expression pattern, functional characterization, and anti-tumor activity of blocking antibodies targeting PVRIG as well as characterization of PVRIG KO mice. Materials and Methods: PVRIG is expressed by T and NK cells within the tumor microenvironment. We identified PVRL2 as its counterpart and characterized the PVRIG-PVRL2 interaction. Antibody discovery was carried out with phage display and hybridoma platforms and antibodies against the human protein were screened for their ability to enhance T-cell activity in vitro, while surrogate antibodies targeting the mouse protein were assessed in syngeneic models for effects on tumor growth. PVRIG -/- KO mice were generated and characterized including phenotyping and anti-tumor immune response. Results: PVRIG is expressed on different T cell subsets and on NK, NKT and γδ T-cells. Within T cells, memory subsets possess the highest level of PVRIG and its expression is induced upon long term activation with different stimuli. Within tumor microenvironment, PVRIG was found to be expressed on NK and CD8+ T cells in multiple cancers. A high affinity lead Ab was selected, COM701, for further clinical development and demonstrated blockade of the interaction of PVRIG with PVRL2 as well as enhancement of activation of both primary and tumor-derived effector immune cells through a PVRL2-dependent mechanism. Moreover, COM-701 showed notable enhancement of T cell function in-vitro when combined with PD1 or TIGIT Ab blockade. The lead antibody, COM-701, is currently in preclinical development. A surrogate antibody, that blocks PVRIG-PVRL2 interaction, was shown to inhibit growth of colon carcinoma and melanoma in syngeneic models upon combined treatment with anti-PDL1 antibody. Comparative analysis of PVRIG KO versus WT derived T cells revealed enhanced reactivity of PVRIG null T cells upon polyclonal activation in presence of PVRL2-Ig. Accordingly, MC38 tumors grew slower in PVRIG KO than in WT mice and ex vivo analysis pointed to the quantitative and functional differences in anticancer immunity developed in these mice. Conclusion: We describe the identification of PVRIG as a novel T cell immune checkpoint. We further demonstrate that antibody blockade of the PVRIG-PVRL2 interaction has the potential to be efficiently combined with PD1 or TIGIT blockade for enhancing anti-tumor immunity. COM-701 is a high affinity antagonistic antibody that is currently in preclinical development. Taken together, these data demonstrate the utility of targeting PVRIG in addition to other B7 family checkpoints for the treatment of cancer. Citation Format: Ofer Levy, Chris Chan, Gady Cojocaru, Spencer Liang, Eran Ophir, Sudipto Ganguly, Maya Kotturi, Tal Friedman, Benjamin Murter, Liat Dassa, Ling Leung, Shirley Greenwald, Meir Azulay, Sandeep Kumar, Zoya Alteber, Xiaoyu Pan, Andy Drake, Ran Salomon, Arthur Machlenkin, John Hunter, Zurit Levine, Drew Pardoll, Mark White. Discovery and development of COM701, a therapeutic antibody targeting the novel immune checkpoint PVRIG [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 581. doi:10.1158/1538-7445.AM2017-581

Computational discovery and experimental validation of novel drug targets in immuno-oncology

The past few years have witnessed a renaissance in the field of immuno-oncology largely due to the clinical success in targeting the immune checkpoints CTLA-4 and PD-1. Towards identification of novel immune checkpoint drug targets we developed a dedicated predictive discovery platform. The B7/CD28 discovery platform is a predictive model based on genomic and protein features along with expression patterns of known B7/CD28 proteins. The platform has been tested and validated extensively and has demonstrated its validity by identifying non-novel immune checkpoints such as TIGIT and VISTA, which were not used in the design stage. The B7/CD28 predictive platform was employed to identify several novel immune checkpoint candidates which are currently in different validation stages. In this poster, we will describe our discovery approach as well as our validation path. In addition, we will present experimental data demonstrating the immuno-modulatory function and expression patterns of several of our novel immune checkpoints. These experimental results serve as an additional confirmation to the accuracy of our B7/CD28 predictive discovery platform and shed light on the therapeutic potential of the novel immune checkpoints identified using this unique discovery approach.

Abstract 5027: Identification of novel immune checkpoints as potential targets for cancer immunotherapy

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Members of the B7/CD28 family of immune checkpoints, such as CTLA4, PD1 and PDL-1, play critical roles in immune cell regulation and have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional immune checkpoints play a role as negative immune regulators and thus may serve as targets for therapeutic mAbs. Utilizing Compugens predictive discovery platform, we identified novel members of this family that may serve as immune checkpoints. The therapeutic relevance of three of these proteins, CGEN-15001T, CGEN-15022, and CGEN-15049, was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Two of these proteins, CGEN-15001T and CGEN-15022, are the basis of a license and collaboration agreement recently signed with Bayer as targets for cancer immunotherapy. Here we present results obtained for an additional novel immune checkpoint, CGEN-15049. Following its ectopic expression on cancer cell lines, CGEN-15049 inhibits the activity of NK cells and cytotoxic T cells (CTLs). The fusion protein, consisting of the extracellular domain of CGEN-15049 fused to an IgG Fc domain, displays robust inhibition of T cell activation and enhances iTregs differentiation. IHC studies indicate that CGEN-15049 is expressed in tumor cells of numerous types of cancers, as well as in tumor infiltrating immune cells. Based on its immunomodulatory activities on immune cell types with key roles in cancer immune evasion, together with its expression pattern in cancer tissues, CGEN-15049 may serve as mAb target for cancer immunotherapy. Citation Format: Galit Rotman, Ofer Levy, Amir Toporik, Gady Cojocaru, Liat Dassa, Ilan Vaknin, Shirley Sameah-Greenwald, Inbal Barbiro, Jinhong Fan, Susan Watson, John Hunter, Eyal Neria, Zurit Levine. Identification of novel immune checkpoints as potential targets for cancer immunotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5027. doi:10.1158/1538-7445.AM2014-5027

Abstract B291: Identification of novel immune checkpoints and their implementation as mAb targets for cancer immunotherapy.

Immune checkpoints, such as CTLA4 and PD-1, have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional novel members of the B7/CD28 family play a role in T cell regulation and thus may serve as targets for therapeutic mAbs. However, the discovery of novel family members is challenging since proteins of the immune system, including proteins of the B7 protein In order to identify novel members of the B7/CD28 protein family, Compugen has developed a discovery approach integrating gene and protein information with extensive expression data, and has identified nine novel membrane proteins that possess characteristics of the B7/CD28 protein family members and are therefore predicted to play a role in T cell co-stimulation. In order to validate our predictive discovery findings, we evaluated the effect of our proteins on immune cells, particularly T cells. For that goal, we expressed the proteins on the cell surface upon ectopic expression, and also produced fusion proteins consisting of the extracellular domain of the predicted proteins, fused to an IgG Fc domain. Here we present results obtained for two of our novel proteins, CGEN-15001T and CGEN-15022. Both display robust inhibition of T cell activation. Interestingly, CGEN-15001, one of the Fc-fused proteins, leads to increased levels of anti-inflammatory cytokines such as IL-4 and IL5, while reducing pro-inflammatory cytokines such as IFN-γ and IL-17. In addition, CGEN-15001 was found to enhance iTregs differentiation. Furthermore, these molecules showed therapeutic efficacy in mouse models of multiple sclerosis and rheumatoid arthritis. To investigate the potential of these membrane proteins as drug targets for treatment of cancer we have performed extensive IHC studies, on a variety of healthy and malignant tissues. Both CGEN-15001T and CGEN-15022 were found to be expressed in numerous types of cancers, each showing a unique pattern of expression. CGEN-15001T, in addition to its expression on tumor cells, was found to be expressed on tumor infiltrating immune cells, especially on Macrophages and Mast cells. Based on the immunomodulatory activities and the expression pattern on malignant and immune cells, CGEN15001T and CGEN15022 may serve as mAb targets for cancer immunotherapy. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B291. Citation Format: Gady Cojocaru, Ofer Levy, Amir Toporik, Liat Dassa, Iris Hecht, Ilan Vaknin, Sergey Nemzer, Tania Pergan, Amit Novik, Shirley Sameah-Greenwald, Anat Oren, Zohar Tiran, Peter Steinberger, Joseph Podojil, Nora Tarcic, Eyal Neria, Galit Rotman, Zurit Levine. Identification of novel immune checkpoints and their implementation as mAb targets for cancer immunotherapy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B291.