B7-H5 is mainly expressed in myeloid cells such as macrophages, monocytes, dendritic cells, and T cells [12], and B7-H5 is highly expressed in a variety of tumors, including melanoma, pancreatic cancer, prostate cancer, non-small cell lung cancer, renal cell carcinoma, and CRC [13–17]. Here, VSIR is linked to prostate cancer.