A major goal of cancer immunotherapy has been to re-activate quiescent tumor-associated T-cells to enhance their detection and killing of cancer cells in tumor microenvironments. It is well established that with persistent activation of T- cells, in chronic inflammation and cancer, immune suppressive checkpoints exist that inhibit T- cell activation to limit collateral damage to host tissues. Building on this knowledge cancer therapies have been developed that block T-cell checkpoints using monoclonal antibodies. Checkpoint blocking strategies that have targeted the inhibition of two T-cell checkpoints, PD-1 and CTLA-4, have been curative for some cancers. However, a majority of patients either do not respond or the responses are not durable. A likely reason for this is the presence of other immune regulatory systems that suppress T-cell function in tumors, including T regulatory cells and myeloid derived suppressor cells that perhaps must also be eliminated. Recently there has been a growing awareness that nano-sized extracellular vesicles present in tumors are able to arrest T-cell function. We have isolated micro-vesicles called exosomes (EX) from human tumors that bind to and internalize into T-cells resulting in a rapid and reversible blockade in the activation potential of these cells. The immunosuppressive EX represents a new T- cell checkpoint that results in an arrest of the activation the T-cell signaling cascade. The suppression of T-cells has been causally linked to phosphatidylserine (PS) expressed on the surface of the EX. Several non-toxic water soluble organic molecules that bind PS have been synthesized by our collaborators at MTTI, and have been screened and shown by us at IMT LLC, to block/reverse the immune suppressive activity of tumor-associated EX. One of the PS binding molecules, Zn- T-DPA, significantly inhibits the T-cell immune suppression of the tumor-associated EX in vitro. . In Aim 1 the pharmacokinetics (PK), the bio-availability and toxicity of Zn-T-DPA, will be addressed in globally immune deficient NSG naive mice, and in these mice bearing human ovarian tumor xenografts. In Aim 2 we will determine the pharmacodynamics (PD) of this molecule in vivo. We predict, and will test here, that treatment in vivo with Zn-T-DPA (at a dose determined in Aim 1) of NSG mice bearing human ovarian tumor xenografts will block or reverse the T-cell suppression by the tumor-associated exosomes, re-activate patients? tumor- associated T-cells, and enhance tumor killing in the tumor microenvironment. With our novel xenograft model (that includes tumor stroma, the tumor-associated T-cells, and exosomes) we are able to quantify several matrices including changes in tumor cell number, serum levels of human cytokines, and in the number and activation potential of the tumor- associated T-cells. Our in vivo studies in Phase 1 of this application are expected to provide a rationale and underpinning for a Phase II application to study the PK, PD and efficacy of the Zn-T-DPA in combination with currently used checkpoint inhibition therapies, and provide for a scale up development of the Zn-T-DPA for a Phase I clinical trial.
Project Terms: Address; Anatomy; annexin A5; anti-cancer therapeutic; Antibodies; Antitumor Response; Ascites; Awareness; base; Binding; Binding Proteins; Biological Assay; Biological Availability; Caliber; cancer cell; cancer immunotherapy; Cancer Patient; cancer therapy; CD8-Positive T-Lymphocytes; Cell Count; Cell physiology; Cells; checkpoint inhibition; chemotherapy; Chronic; Clinical; Combination Drug Therapy; Confocal Microscopy; cytokine; Cytotoxic T-Lymphocyte-Associated Protein 4; Data; Detection; Development; Dose; Drug Exposure; Drug Kinetics; drug testing; exosome; experience; extracellular vesicles; Flow Cytometry; Goals; Grant; Greater omentum; Head; high throughput screening; Human; Immune; Immune Cell Suppression; Immunosuppression; Immunosuppressive Agents; improved; In Vitro; in vivo; Inflammation; Injections; Interleukin-12; Knowledge; Legal patent; Leukocytes; Link; Lipid Bilayers; Liposomes; Liquid substance; Malignant neoplasm of ovary; Malignant Neoplasms; microvesicles; Modeling; Monitor; Monoclonal Antibodies; Morphology; Mus; Myeloid-derived suppressor cells; nanosized; neoplastic cell; novel; Omentum; Organ; ovarian neoplasm; Ovarian Surface Epithelial-Stromal Tumor; Pathologist; patient response; Patients; Peritoneal Fluid; Pharmaceutical Preparations; pharmacodynamic model; Pharmacodynamics; pharmacokinetic model; Phase; Phase I Clinical Trials; Phenotype; Phosphatidylserines; Phospholipids; pre-clinical; prevent; Proteins; Protocols documentation; public health relevance; Publishing; Regulatory T-Lymphocyte; response; scale up; Schedule; screening; Serum; Signal Transduction; Site; small molecule; Solid Neoplasm; Surface; System; T cell response; T-Cell Activation; T-Lymphocyte; Techniques; Testing; Therapeutic; Time; Tissues; Toxic effect; Treatment Efficacy; tumor; tumor microenvironment; Tumor Suppression; Tumor Tissue; tumor xenograft; Tyrosine; Vesicle; Water; Xenograft Model; Xenograft procedure; Zinc;
