CD274 and head and neck carcinoma: Additional studies confirmed that tumors with high MSI instability status correlate with high levels of PD1/PDL1 expression [43,44] and represent predictive markers of response to immunotherapy [45] in several tumors including colorectal cancer [46,47], endometrial cancer [48], gastric cancer [49], follicular thyroid cancer [50], and head and neck carcinoma [51].