Abstract PO-049: SARS-CoV-2 Multiepitope Vaccine Constructs Designed to Drive Long-Term Immunity in the Majority of the Population

Abstract The current SARS-CoV-2 pandemic has precipitated an urgent need for a safe and effective vaccine to be developed and deployed in a highly accelerated timeframe as compared to standard vaccine development processes. Upfront selection of epitopes most likely to induce a safe and effective immune response can accelerate these efforts. Optimally designed vaccines maximize immunogenicity towards regions of proteins that contribute most to protective immunity, while minimizing the antigenic load contributed by unnecessary protein domains that may result in autoimmunity, reactogenicity, or enhanced infectivity. Adopting tools developed for population-scale characterization of HLA presentation of tumor antigens and cross-reactivity of TCRs with tumor self-antigens, we have generated an immunogenicity map of SARS-CoV-2 to inform vaccine design based on analyses across five parameters: 1) stimulation of CD4 and CD8 T cells; 2) immunogenicity across the majority of human HLA alleles; 3) targeting both evolutionarily conserved regions, as well as newly divergent regions of the virus that increase infectivity; 4) targeting linear and conformational B-cell epitopes; and 5) targeting viral regions with the highest degree of dissimilarity to the self-immunopeptidome such as to maximize safety and immunogenicity. Using these analyses, we have generated 11 SARS-CoV-2 vaccine constructs optimized for long-term immunity across the majority of the population. These constructs contain combinations of epitopes selected from our analysis such as to drive affinity-enhanced memory response in combination with current spike protein vaccine strategies, for use as T-cell vaccines, and a stand-alone vaccine designed to drive memory B- and T-cell responses in the majority of the population. Epitopes were optimized using our immunogenicity algorithm to minimize immunogenicity across the junctions between epitopes and cloned into pVAX vectors, using signal peptides targeting the lysosome, ER, and cytoplasmic secretion, such as to promote presentation to CD4, CD8, and B cells, respectively. Finally, we describe methods for identifying immunodominant epitopes arising from vaccination using barcoded, multiplexed tetramers. Vaccine constructs are currently undergoing testing in transgenic mice expressing human HLA-A2. We expect that these constructs will help drive long-term immunity across the population, targeting conserved regions across multiple coronaviruses. Citation Format: Mark Yarmarkovich, John M. Warrington, Alvin Farrel, John M. Maris. SARS-CoV-2 multiepitope vaccine constructs designed to drive long-term immunity in the majority of the population [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2020 Jul 20-22. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(18_Suppl):Abstract nr PO-049.