In cancer, CAR exosomes derived from effector CAR-T cells have potent anti-tumor effects and low toxicity [290,291], tumor-produced PD-L1-expressing exosomes contribute to immunosuppression [292,293], and tumor stem cell-derived exosomes induce M2 macrophages and PD-L1 expression on human monocytes [294]. Here, CD274 is linked to neoplasm.