Codiak BioSciences, Inc. announced new preclinical data from its pan beta-coronavirus vaccine program, which aims to protect against all SARS-CoV-2 variants of concern and potential future strains belonging to the beta-coronavirus family. The data, which are being presented at the World Vaccine Congress 2022 in Washington, D.C., demonstrate the potential for a novel engineered exosome-based vaccine candidate derived from Codiak's exoVACC™ platform to induce cross-neutralizing antibody protection against multiple strains of coronaviruses and an antigen-specific and comprehensive immune response against structurally conserved regions of multiple coronavirus variants. Codiak's proprietary and modular vaccine platform leverages engineered exosomes – naturally occurring, extracellular nanoparticle vesicles – to precisely control antigen display on the surface or in the lumen, in order to deliver antigens, adjuvants and immunomodulators simultaneously and selectively to antigen presenting cells to maximize immune response.

The pan beta-coronavirus vaccine construct, developed in collaboration with the Ragon Institute of MIT, MGH and Harvard, carries the receptor-binding domain (RBD) protein of both SARS-CoV-1 and SARS-CoV-2 at high density on the surface of the exosome, combined with structurally constrained, highly conserved T cell antigens expressed in the lumen, and stable loading of a STING agonist as an adjuvant. This design closely resembles the natural viral structures and is amendable to multiple routes of administration, including subcutaneous, intramuscular and intranasal. Preclinical data presented late last year demonstrate that Codiak's vaccine candidate stimulates a comprehensive immune response conferring both antibody and T cell-mediated immunity, a neutralizing antibody response against multiple SARS-CoV-2 variants and the ability to illicit antigen-specific T cell responses against structurally conserved regions of all known coronavirus variants of concern.

Key conclusions from additional preclinical studies presented include: Evidence of a durable antibody response lasting at least eight months in a mouse model; Induction of mucosal immune responses in vaccinated mice that were equivalent to responses in humans vaccinated with an mRNA vaccine and induction of lung resident memory CD4 and CD8 T cells when administered intranasally; Generation of cross-protective neutralizing antibodies in response to vaccination with an exosome carrying the RBD proteins for both SARS-CoV1 and SARS-CoV-2; and Upon challenge with the Delta variant, 100% survival and minimal evidence of infection in lung tissues. The T cell epitopes used in the vaccine constructs were identified by Gaurav Gaiha, M.D., principal investigator at the Ragon Institute. These structural pieces of the virus are believed to be invariant, lending the candidate the ability to generate CD8 T cell responses that are potentially protective against all beta-coronaviruses, and, in preclinical models of SARS-CoV-2 infection, served to further enhance the overall immune response.