CD274 and neoplasm: However, not all patients have finished PD-L1 detection, for a number of reasons including limited biopsy tissue, low quality tissue samples as samples that must comprise sufficient amounts of tumor cells, lymphocytes and phagocytes and as certain patients started immunotherapy before PD-L1 was recognized as a clinically relevant biomarker for ICIs in November 2020, when the US FDA accelerated the approval of pembrolizumab in combination with chemotherapy based on the positive outcomes of KEYNOTE 355.