The mannose binding lectin Griffithsin (GRFT) represents an exciting new approach to preventing infection by HIV-1 and herpes simplex virus 2 (HSV-2). GRFT binds the dense glycan shield on the HIV-1 and HSV-2 envelopes, for which oligomannose structures are a highly conserved feature. In protecting against HIV, GRFT possesses potent neutralizing activity towards diverse viral strains, and it acts synergistically with chemical antimicrobials and even broadly neutralizing antibodies. In protecting against HSV-2, GRFT has been shown to prevent infection and stop cell-to-cell spread both in vitro and in pre-clinical animal models. Importantly, HSV-2 infection increases the risk of HIV-1 acquisition by 3- to 5-fold in the general population and at least doubles the HIV-1 risk in high risk populations. Thus, GRFTs capacity to protect against infection by both viruses suggests it is a promising agent for Pre-exposure Prophylaxis (PrEP), and we propose that a GRFT-based PrEP microbicide could help dramatically reduce new cases of HIV-1 infection. Indeed, under the NIAID- funded PREVENT Program, we recently received FDA approval for a first-in-human study of our Q-GRFT topical microbicide (Q-GRFT is a variant engineered for enhanced oxidative stability). Notably, as part of GLP toxicology studies for this Investigational New Drug (IND) application, we observed a potent anti-drug antibody (ADA) response in rabbits. This prompted a closer examination of Q-GRFT immunogenicity in two clinically relevant models: human peripheral blood mononuclear cell (PBMC) immunoassays and humanized HLA transgenic mice. We found that Q-GRFT elicited high ADA titers following repeated dosing in HLA transgenic mice, and it was similarly shown to activate helper T cells in PBMC from several healthy human donors. Thus, while Q-GRFT holds great promise in the fight against new HIV-1 infections, our preclinical data strongly suggests that the immunogenicity issue must be addressed if Q-GRFT is to be employed, long-term, as a PrEP agent. We propose here to design and develop a next-generation deimmunized GRFT (dGRFT) microbicide that retains the potent and broad-spectrum antiviral activity of wild type and Q-GRFT but evades detrimental anti-drug immune responses in humans. To achieve this goal, we will combine Stealth Biologics advanced protein design and deimmunization platform with the deep expertise and experience of the development team, which has already pushed Q-GRFT into clinical trials. In Phase I of this Fast-track SBIR proposal, we will develop a dGRFT lead candidate and validate it using preliminary immunological and functional assays. In Phase II of this Fast-track proposal, we will confirm dGRFTs breadth of antiviral activity, demonstrate reduced immunogenic potential in large and diverse PBMC donor panels, develop a scalable manufacturing system, assess dGRFT toxicity in both standard and humanized animal models, and test the agents prophylactic efficacy in clinically-relevant animal models of HSV-2 and HIV infection. Upon completion of this grant, we will have in hand a high-performance dGRFT lead candidate that is positioned for IND-enabling studies.
Public Health Relevance Statement: Narrative: Griffithsin is a glycan-binding lectin with high affinity for both HIV-1 gp120 and HSV-2 gD glycoproteins, and it is a powerful neutralizing agent for enveloped viruses, preventing infection by both HIV and HSV. Griffithsin is thus a promising biotherapeutic candidate for Pre-Exposure Prophylactic (PrEP) prevention of HIV and HSV infections, but as a non-human protein, it exhibits undesirable immunogenicity in higher animals. This program will employ Stealth Biologics® cutting edge technology platform to deimmunize Griffithsin, creating a first-in-class antiviral microbicide that offers potent antiviral protection and is safe for long- term use as a PrEP agent.
Project Terms: 3-Dimensional; Address; Affinity; AIDS prevention; Animal Model; Animals; Anti-HIV Therapy; Anti-Retroviral Agents; Antibody Response; Antibody titer measurement; antimicrobial; Antiretroviral resistance; antiretroviral therapy; Antiviral Agents; base; Binding; Biological; Biological Assay; Biological Response Modifier Therapy; candidate selection; Cell-Mediated Cytolysis; Cells; Cellular Assay; cervicovaginal; Chemicals; Chronic; Clinical; Clinical Trials; clinically relevant; cofactor; cytotoxic; Data; de-immunization; design; Development; Dose; efficacy testing; Engineering; Epitopes; Exhibits; experience; Female; fight against; Film; first-in-human; Funding; Future; General Population; Glycoproteins; Goals; Grant; Hand; Health; Helper-Inducer T-Lymphocyte; high risk; high risk population; HIV; HIV Envelope Protein gp120; HIV Infections; HIV-1; Human; Human Herpesvirus 2; human study; human subject; humanized mouse; Immune response; Immunoassay; immunogenic; immunogenicity; Immunologic Surveillance; Immunologics; immunoreaction; Immunotherapeutic agent; improved; In Vitro; in vivo evaluation; indexing; Infection; Infection prevention; Investigational Drugs; Investigational New Drug Application; irritation; Lead; lead candidate; Lectin; Local Microbicides; Macaca mulatta; Mannose Binding Lectin; manufacturing process; Maps; Measures; meetings; microbicide; Modeling; Morbidity - disease rate; Mus; nanomolar; National Institute of Allergy and Infectious Disease; neutralizing antibody; next generation; Nicotiana; Non-Human Protein; novel strategies; Oryctolagus cuniculus; oxidation; Patients; Peptides; Performance; Peripheral Blood Mononuclear Cell; Pharmaceutical Preparations; Phase; Phase I Clinical Trials; Polysaccharides; Population; Positioning Attribute; pre-clinical; pre-exposure prophylaxis; preclinical efficacy; Prevention; Process; Production; programs; prophylactic; Protein Engineering; Proteins; Quality Control; Refractory; Research Personnel; Resistance; response; Risk; Risk Factors; Running; Safety; safety testing; Sex Behavior; Sexual Partners; Sexually Transmitted Diseases; simian human immunodeficiency virus; Simplexvirus; Small Business Innovation Research Grant; Source; Structure; synergism; System; T-Lymphocyte; T-Lymphocyte Epitopes; Technology; Testing; Tissues; Toxic effect; Toxicology; Transfection; Transgenic Mice; Transgenic Organisms; transmission process; truvada; Universities; Vagina; vaginal mucosa; Variant; Viral; Virus; Virus Diseases; virus envelope
