PDCD1 and head and neck squamous cell carcinoma: For instance, a triple combination of CTLA-4, PD-1, and PDL-1 blocking ICI, ipilimumab, pembrolizumab, and durvalumab, is about to be tested for 100 patients with advanced solid tumors including HNSCC in a recruiting phase I/II trial (trial identifier: 'NCT05187338) (Table 1; Figure 2).