Cellular therapies are engineered using foreign and synthetic protein sequences, such as chimeric antigen receptors (CARs). The frequently observed humoral responses to CAR T cells result in rapid clearance, especially after re-infusions. There is an unmet need to protect engineered cells from host-versus-graft rejection, particularly for the advancement of allogeneic cell therapies. Here, utilizing the immunoglobulin G (IgG) protease "IdeS," we programmed CAR T cells to defeat humoral immune attacks. IdeS cleavage of host IgG averted Fc-dependent phagocytosis and lysis, and the residual F(ab')2 fragments remained on the surface, providing cells with an inert shield from additional IgG deposition. "Shield" CAR T cells efficiently cleaved cytotoxic IgG, including anti-CAR antibodies, detected in patient samples and provided effective anti-tumor activity in the presence of anti-cell IgG in vivo. This technology may be useful for repeated human infusions of engineered cells, more complex engineered cells, and expanding widespread use of "off-the-shelf" allogeneic cellular therapies.
Keywords: CAR T cells; IdeS; anti-CAR IgG; cell therapies; humoral response; immunogenicity.
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