Third, although we used an anti-PD1 drug, all our cases had either low or no PD-L1 expression; however, PD-L1 expression was not predictor of anti-PD1 efficacy in many trials analysing these agents in various types of tumors [26,27]; in particular, pembrolizumab showed limited benefit in selected patients with PD-L1 positive recurrent glioblastoma [15]. This evidence concerns the gene CD274 and glioblastoma.