Synthetic Multiantigen MVA Vaccine COH04S1 Protects Against SARS-CoV-2 in Syrian Hamsters and Non-Human Primates

Second-generation COVID-19 vaccines could contribute to establish protective immunity against SARS-CoV-2 and its emerging variants. We developed COH04S1, a synthetic multiantigen Modified Vaccinia Ankara-based SARS-CoV-2 vaccine that co-expresses spike and nucleocapsid antigens. Here, we report COH04S1 vaccine efficacy in animal models. We demonstrate that intramuscular or intranasal vaccination of Syrian hamsters with COH04S1 induces robust Th1-biased antigen-specific humoral immunity and cross-neutralizing antibodies (NAb) and protects against weight loss, lower respiratory tract infection, and lung injury following intranasal SARS-CoV-2 challenge. Moreover, we demonstrate that single-dose or two-dose vaccination of non-human primates with COH04S1 induces robust antigen-specific binding antibodies, NAb, and Th1-biased T cells, protects against both upper and lower respiratory tract infection following intranasal/intratracheal SARS-CoV-2 challenge, and triggers potent post-challenge anamnestic antiviral responses. These results demonstrate COH04S1-mediated vaccine protection in animal models through different vaccination routes and dose regimens, complementing ongoing investigation of this multiantigen SARS-CoV-2 vaccine in clinical trials.

Development of a multi-antigenic SARS-CoV-2 vaccine candidate using a synthetic poxvirus platform

Modified Vaccinia Ankara (MVA) is a highly attenuated poxvirus vector that is widely used to develop vaccines for infectious diseases and cancer. We demonstrate the construction of a vaccine platform based on a unique three-plasmid system to efficiently generate recombinant MVA vectors from chemically synthesized DNA. In response to the ongoing global pandemic caused by SARS coronavirus-2 (SARS-CoV-2), we use this vaccine platform to rapidly produce fully synthetic MVA (sMVA) vectors co-expressing SARS-CoV-2 spike and nucleocapsid antigens, two immunodominant antigens implicated in protective immunity. We show that mice immunized with these sMVA vectors develop robust SARS-CoV-2 antigen-specific humoral and cellular immune responses, including potent neutralizing antibodies. These results demonstrate the potential of a vaccine platform based on synthetic DNA to efficiently generate recombinant MVA vectors and to rapidly develop a multi-antigenic poxvirus-based SARS-CoV-2 vaccine candidate.

Development of a Multi-Antigenic SARS-CoV-2 Vaccine Using a Synthetic Poxvirus Platform

Modified Vaccinia Ankara (MVA) is a highly attenuated poxvirus vector that is widely used to develop vaccines for infectious diseases and cancer. We developed a novel vaccine platform based on a unique three-plasmid system to efficiently generate recombinant MVA vectors from chemically synthesized DNA. In response to the ongoing global pandemic caused by SARS coronavirus-2 (SARS-CoV-2), we used this novel vaccine platform to rapidly produce fully synthetic MVA (sMVA) vectors co-expressing SARS-CoV-2 spike and nucleocapsid antigens, two immunodominant antigens implicated in protective immunity. Mice immunized with these sMVA vectors developed robust SARS-CoV-2 antigen-specific humoral and cellular immune responses, including potent neutralizing antibodies. These results demonstrate the potential of a novel vaccine platform based on synthetic DNA to efficiently generate recombinant MVA vectors and to rapidly develop a multi-antigenic poxvirus-based SARS-CoV-2 vaccine candidate.

Development of a Synthetic Poxvirus-Based SARS-CoV-2 Vaccine

Modified Vaccinia Ankara (MVA) is a highly attenuated poxvirus vector that is widely used to develop vaccines for infectious diseases and cancer. We developed a novel vaccine platform based on a unique three-plasmid system to efficiently generate recombinant MVA vectors from chemically synthesized DNA. In response to the ongoing global pandemic caused by SARS coronavirus-2 (SARS-CoV-2), we used this novel vaccine platform to rapidly produce fully synthetic MVA (sMVA) vectors co-expressing SARS-CoV-2 spike and nucleocapsid antigens, two immunodominant antigens implicated in protective immunity. Mice immunized with these sMVA vectors developed robust SARS-CoV-2 antigen-specific humoral and cellular immune responses, including potent neutralizing antibodies. These results demonstrate the potential of a novel vaccine platform based on synthetic DNA to efficiently generate recombinant MVA vectors and to rapidly develop a multi-antigenic poxvirus-based SARS-CoV-2 vaccine candidate.

Enfortumab Vedotin Antibody-Drug Conjugate Targeting Nectin-4 Is a Highly Potent Therapeutic Agent in Multiple Preclinical Cancer Models

The identification of optimal target antigens on tumor cells is central to the advancement of new antibody-based cancer therapies. We performed suppression subtractive hybridization and identified nectin-4 (PVRL4), a type I transmembrane protein and member of a family of related immunoglobulin-like adhesion molecules, as a potential target in epithelial cancers. We conducted immunohistochemical analysis of 2,394 patient specimens from bladder, breast, lung, pancreatic, ovarian, head/neck, and esophageal tumors and found that 69% of all specimens stained positive for nectin-4. Moderate to strong staining was especially observed in 60% of bladder and 53% of breast tumor specimens, whereas the expression of nectin-4 in normal tissue was more limited. We generated a novel antibody-drug conjugate (ADC) enfortumab vedotin comprising the human anti-nectin-4 antibody conjugated to the highly potent microtubule-disrupting agent MMAE. Hybridoma (AGS-22M6E) and CHO (ASG-22CE) versions of enfortumab vedotin (also known as ASG-22ME) ADC were able to bind to cell surface-expressed nectin-4 with high affinity and induced cell death in vitro in a dose-dependent manner. Treatment of mouse xenograft models of human breast, bladder, pancreatic, and lung cancers with enfortumab vedotin significantly inhibited the growth of all four tumor types and resulted in tumor regression of breast and bladder xenografts. Overall, these findings validate nectin-4 as an attractive therapeutic target in multiple solid tumors and support further clinical development, investigation, and application of nectin-4-targeting ADCs. Cancer Res; 76(10); 3003-13. ©2016 AACR.

AGS16F Is a Novel Antibody Drug Conjugate Directed against ENPP3 for the Treatment of Renal Cell Carcinoma

PURPOSE

New cancer-specific antigens are required for the design of novel antibody-drug conjugates (ADC) that deliver tumor-specific and highly potent cytotoxic therapy.

EXPERIMENTAL DESIGN

Suppression subtractive hybridization identified ectonucleotide pyrophosphatase/phosphodiesterase 3 (ENPP3 or CD203c) as a potential human cancer-specific antigen. Antibodies targeting the extracellular domain of human ENPP3 were produced and selected for specific binding to ENPP3. Expression of ENPP3 in normal and cancer tissue specimens was evaluated by immunohistochemistry (IHC). ADCs comprising anti-ENPP3 Ab conjugated with maleimidocaproyl monomethyl auristatin F via a noncleavable linker (mcMMAF) were selected for therapeutic potential using binding and internalization assays, cytotoxicity assays, and tumor growth inhibition in mouse xenograft models. Pharmacodynamic markers were evaluated by IHC in tissues and ELISA in blood.

RESULTS

ENPP3 was highly expressed in clear cell renal cell carcinoma: 92.3% of samples were positive and 83.9% showed high expression. By contrast, expression was negligible in normal tissues examined, with the exception of the kidney. High expression was less frequent in papillary renal cell carcinoma and hepatocellular carcinoma samples. AGS16F, an anti-ENPP3 antibody-mcMMAF conjugate, inhibited tumor growth in three different renal cell carcinoma (RCC) xenograft models. AGS16F localized to tumors, formed the active metabolite Cys-mcMMAF, induced cell-cycle arrest and apoptosis, and increased blood levels of caspase-cleaved cytokeratin-18, a marker of epithelial cell death.

CONCLUSIONS

AGS16F is a promising new therapeutic option for patients with RCC and is currently being evaluated in a phase I clinical trial.

Abstract 1314: Molecular profiling and characterization of patient-derived human pancreatic tumor xenograft models, and application for drug discovery and preclinical development of cancer therapeutics

A major obstacle that has hampered the development and assessment of novel anticancer therapies is the inability of the conventional xenograft models to reliably predict clinical efficacy. This is in part due the fact that the cell lines used for these studies are cultured on plastic for extensive passages and lack the human extracellular matrix component that is critical for cancer-stromal cell interactions. Models are needed which more accurately reflect tumor heterogeneity and interaction with the tumor microenvironment in order to more accurately reflect tumor complexity and predict response to therapies in the clinic. This has led to the development of models by directly engrafting cancer patient-derived tumor tissues into immunodeficient mice with the aim of retaining histopathological features and molecular characteristics of the original tumor. A vital question relating to patient-derived tumor xenografts is whether tumor characteristics are maintained during passaging. We have established a number of proprietary pancreatic cancer patient-derived xenografts. Studies were performed to molecularly characterize the xenograft models and to confirm they retain similarity to the original tumors. Original patient tumors and corresponding serial xenograft passages were examined for growth, histopathological features and protein expression, as well as genomic and tumor biomarker status. Examination of these patient-derived xenograft models demonstrated that tumor morphology is maintained upon passaging. Immunohistochemical and qPCR analysis of targets of interest showed that expression levels are consistent between tumors and xenograft passages. Although slight differences were observed in genomic profiles for some individual models after engraftment in mice, whole genome profiling by microarray and aCGH revealed that individual tumor models retain organ-specific characteristics and that xenografts remain stable throughout passaging. Core sets of significantly expressed genes and genomic aberrations were maintained, with some additional changes observed during passaging. Retention of the characteristics of the original donor tumors within the xenograft models, such as tumor architecture and molecular signatures will afford the use of models which more accurately reflect patient tumor biology. Comprehensive molecular characterization of our models was utilized to investigate differential response to our proprietary drug candidates. Expanded testing in multiple models can potentially provide important pre-clinical translational information to help guide clinical trial design regarding patient subpopulations that may be more likely to respond to therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1314. doi:1538-7445.AM2012-1314

Overlapping but separable determinants of DNA binding and nuclear localization map to the C-terminal end of the Caenorhabditis elegans DAF-12 DNA binding domain

Proteins are commonly viewed as modular assemblies of functional domains. We analyzed a loss-of-function mutation in the Caenorhabditis elegans intracellular receptor DAF-12, a conservative substitution of an arginine to a lysine at position 197 (R197K). Arg(197) resides in region similar to a nuclear localization signal, just downstream of the receptor minimal zinc finger DNA binding domain (DBD) core. We found that the R197K, but not mutations of neighboring arginine or lysine residues, dramatically reduced DAF-12 transcriptional regulatory activity in a yeast reporter assay. This reduction in regulatory activity correlated with greatly decreased DNA binding affinity in vitro, suggesting a role for the DAF-12 DBD C-terminal region (dbdC), and specifically for Arg(197), in DNA binding. Remarkably, three basic residues immediately contiguous with Arg(197) played little role in DNA binding and rather affected nuclear localization; in contrast, Arg(197) itself was dispensable for nuclear localization. Thus, DAF-12 dbdC harbors overlapping but separable determinants of DNA binding and nuclear localization in a single small region.

Identification of C. elegans DAF-12-binding sites, response elements, and target genes

Intracellular receptor DAF-12 regulates dauer formation and developmental age and affects Caenorhabditis elegans lifespan. Genetic analyses place DAF-12 at the convergence of several signal transduction pathways; however, the downstream effectors and the molecular basis for the receptor's multiple physiological outputs are unknown. Beginning with C. elegans genomic DNA, we devised a procedure for multiple rounds of selection and amplification that yielded fragments bearing DAF-12-binding sites. These genomic fragments mediated DAF-12-dependent transcriptional regulation both in Saccharomyces cerevisiae and in C. elegans; that is, they served as functional DAF-12 response elements. We determined that most of the genomic fragments that displayed DAF-12 response element activity in yeast were linked to genes that were regulated by DAF-12 in C. elegans; indeed, the response element-containing fragments typically resided within clusters of DAF-12-regulated genes. DAF-12 target gene regulation was developmental program and stage specific, potentially predicting a fit of these targets into regulatory networks governing aspects of C. elegans reproductive development and dauer formation.

Ultrastructural identification of storage compartments and localization of activity-dependent secretion of neurotrophin 6 in hippocampal neurons

A modulatory role of neurotrophins (NTs) in activity-dependent neuronal plasticity by pre- and postsynaptic mechanisms is now well established. In this context, it is important to identify the storage compartments and to localize the precise site(s) and mechanism of NT secretion in order to deduce the spatial and temporal availability of NTs. We approached these questions at the ultrastructural level, exploiting the unique property of NT6 to bind tightly to heparan sulfate proteoglycans at the neuronal surface (R. Götz et al., 1994, Nature 372, 266-269), permitting the localization of secretion sites excluding diffusion artifacts. The myc tagging of NT6 permitted glutaraldehyde fixation and hence good preservation of the membrane structure, permitting immunogold labeling of NT6myc at the neuronal surface. NT6myc is preferentially secreted from neurites compared to neuronal cell bodies. In agreement with light-microscopic observations, the ultrastructural localization of NT6myc by postembedding procedures showed a predominant localization in ER-like membrane-confined compartments, partially associated with microtubules.

Cooperative assembly of androgen receptor into a nucleoprotein complex that regulates the prostate-specific antigen enhancer

Prostate cancer is characterized by elevated serum levels of prostate-specific antigen (PSA). PSA gene expression is controlled by an androgen-responsive transcriptional enhancer. Our study suggests that formation of a nucleoprotein complex, encompassing 170 base pairs of enhancer DNA, mediates androgen-responsive PSA enhancer activity. The complex is assembled by cooperative binding of androgen receptor to at least four tandem, nonconsensus androgen response elements (AREs). Systematic mutagenesis of the AREs demonstrated that they act synergistically to stimulate androgen receptor-responsive gene expression. We discuss a mechanism whereby a combination of high androgen receptor levels in the prostate and low affinity AREs contribute to the cell type specificity and activity of the enhancer.

A mechanism for hormone-independent prostate cancer through modulation of androgen receptor signaling by the HER-2/neu tyrosine kinase

Prostate cancer progresses from a hormone-sensitive, androgen-dependent stage to a hormone-refractory, androgen-independent tumor. The androgen receptor pathway functions in these androgen-independent tumors despite anti-androgen therapy. In our LAPC-4 prostate cancer model, androgen-independent sublines expressed higher levels of the HER-2/neu receptor tyrosine kinase than their androgen-dependent counterparts. Forced overexpression of HER-2/neu in androgen-dependent prostate cancer cells allowed ligand-independent growth. HER-2/neu activated the androgen receptor pathway in the absence of ligand and synergized with low levels of androgen to 'superactivate' the pathway. By modulating the response to low doses of androgen, a tyrosine kinase receptor can restore androgen receptor function to prostate cancer cells, a finding directly related to the clinical progression of prostate cancer.