Proteins that are mis-localised to the plasma membrane of tumour cells are promising neoepitopes to target with CAR T cells, as shown pre-clinically with a CAR T cell targeting the mitochondrial protein GRP78 to treat AML.445 Targeting such neoepitopes reduces the risk of on-target off-tumour cytotoxicity. The gene discussed is HSPA5; the disease is neoplasm.