CD274 and head and neck squamous cell carcinoma: To date, two phase 2 studies evaluating neoadjuvant anti-PD-1 agents have shown antitumor activity in patients with resectable HNSCC, with clinical to pathological downstaging and PTR rates (defined as a reduction of viable tumor >50%) ranging from 19% and 22% with one dose of pembrolizumab, to 69% and 40% with two doses of nivolumab, respectively.18 32 Similar to what occurred in the recurrent/metastatic setting, PD-L1 expression seemed to enrich for responses in the pembrolizumab study, although this correlation was not observed in the nivolumab study.