For example, a prior study from our group assessed PD-L1 levels using quantitative immunofluorescence in matched pairs of nephrectomy and metastatic sites on tissue microarrays (TMAs), with four biopsy cores used for each tumor specimen, and found a weak correlation in expression between primary and metastatic sites, as well as intra-tumor heterogeneity at all sites (30). This evidence concerns the gene CD274 and neoplasm.