Novel strategy to generate glycan-specific antibodies for cancer immunotherapy

PROJECT SUMMARY ABSTRACT Almost half of all men and women in the United States will be diagnosed with cancer during their lifetimesresulting in more thandeaths and an economic burden exceeding $billion annuallyCancer immunotherapiessuch as vaccines and antibodiesare emerging strategies for specifically targeting malignant cellswhile avoiding the potentially dangerous and unpleasant side effects of traditional treatmentsGiven that cancer is a heterogeneous set of diseasesbroadly effective immunotherapeutics would yield substantial public health and economic benefitsNumerous cancers exhibit altered patterns of cell surface carbohydratesFurthermoreunlike many protein peptide neoantigenssimilar alterations occur across a diversity of malignanciesmaking tumor associated carbohydrate antigens an appealing target for immunotherapy developmentUnfortunatelycarbohydrates are notoriously poor immunogensAs a consequencedespite considerable effort towards realizing the promise of targeting differentially expressed carbohydrate antigensfew therapies or diagnostics have been successfully developedIn those cases where glycans have been successfully targetedit has been the result of years of singularly focused study or serendipity rather than a successful technological advance to be leveragedOne promising strategy to improve the immune response to carbohydrate targets is to use bacterial outer membrane vesiclesOMVsas carriersOMVswhich are composed mainly of periplasmic and outer membrane components of Gram negative bacteriapackage multiple copies of a target antigen along with immunostimulatory components in a singleeasily purified unitGlycobiaIncspecializes in glycoengineering Escherichia coli to produce structurally defined glycoconjugates bearing designer carbohydratesThe central hypothesis of the proposed studies is that glycosylated OMVsglycOMVsthat display tumor associated glycans will stimulate a robust immune response that can be subsequentlyglyco focusedby boosting with the same glycans conjugated to carrier proteins not found on OMVsFollowing this heterologous immunization strategyisolated splenocytes will be used to generate Fabphage display libraries to identify glycan directed Fab antibodies that can be converted to full length monoclonal antibodies for use as direct immunotherapiesor as glycan targeting sequences in next generation modalities such as CAR Tbispecific antibodiesand antibody drug conjugatesThe deliverables of this proposal will be a robust method for antibody discovery that elevates and focuses the immune response to otherwise poor immunogensIt is anticipated that this platform will be broadly applicable to the development of engineered vaccine and antibody based therapies targeting unique carbohydrate antigens that are differentially expressed in human cancers PROJECT NARRATIVE Tumor associated carbohydrate antigensTACAsuch as polysialic acid and ganglioside GDare abundantly expressed on many types of cancer cells including small cell lung cancernon small cell lung cancerbreast cancerpancreatic cancermelanomaneuroblastomaand rhabdomyosarcomamaking them appealing targets for immunotherapeutic antibodiesUnfortunatelydue to their low immunogenicitythe generation of TACA specific antibodies has beento datea significant technical challengeTo address this challengethis proposal seeks to employ a novel heterologous immunization strategy that elevates and focuses the immune response to these poor immunogens to generate class switched IgG antibodies