CD274 and neoplasm: Intriguingly, when PDL1 expression was evaluated, a significant increase in the number of PDL1+ tumor cells was detected in post-vaccination tumor biopsies (11 out of 14 assessable paired biopsies, mean ± SEM 3.721 ± 1.316 vs. 10.37 ± 2.456 PDL1% in pre-treatment and post-treatment biopsies, respectively; p = 0.0353) (Figure 2B).