In addition, CAR-NK cells are safer than CAR T-cells because the cytokines secreted by activated NK cells (e.g., IFN-γ and granulocyte–macrophage colony-stimulating factor (GM-CSF) are safer and typically eliminate the risk of cytokine storm and extreme neurotoxicity caused by pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α), IL-1, and IL-6) released by CAR T-cells [44], and also allogeneic CAR-NKs decrease the risk of GVHD because they are not restricted to MHC [45]. The gene discussed is IL6; the disease is graft versus host disease.