CD40 and neoplasm: The armored CAR-T cells that constitutively express CD40L can engage CD40-positive tumor cells and kill them directly, while activating neighboring antigen presenting cells (APCs) that increase the tumor expression of co-stimulatory molecules such as CD40, CD86 and the class II major histocompatibility complex (MHC), enabling lysis of tumor cells by endogenous T cells even in the absence of target antigen (89).