CD274 and neoplasm: Unfortunately, despite the increased PD-L1 expression observed across NET sites that has been correlated with tumor grade (29, 57), results from the KEYNOTE-028 trial, in which patients with PD-L1 and well-differentiated PNETs were treated with pembrolizumab, were tepid, similar to the results of a trial with spartalizumab (26, 27).