CD274 and cancer: To date, a total of 12 kinds of ICB have been approved for cancer immunotherapy, including seven PD-1 inhibitors (nivolumab, pembrolizumab, cemiplimab, camrelizumab, tislelizumab, toripalimab, and sintilimab), three PD-L1 inhibitors (atezolizumab, durvalumab, and avelumab), and two CTLA-4 inhibitors (ipilimumab and tremelimumab) (Kennedy and Salama, 2020).