FASLG and neoplasm: Chimeric antigen receptor (CAR) T cell therapy mediate tumor killing in several ways, including secretion of cytotoxic granules containing perforin and granzymes, production of pro-inflammatory cytokines such as IFN-g and TNF-a and activation of Fas/Fas ligand (Fas/FasL), elevation of circulating levels of serum cytokines (such as IL-15) and depletion of endogenous regulatory T cells (7).