CD274 and cancer: Although immunohistochemistry (IHC) of biopsy specimens has been approved by the FDA as a companion or complementary diagnostic test for PD-L1 expression levels in certain cancers (e.g. NSCLC, HNSCC, and TNBC), alternative methods are still needed to overcome the pitfalls of the local and static information that is provided from small snapshots of resected tumor tissue.