Combination treatment group had significantly increased proportion of central memory CD8+ T cells in the TME compared to the single treatment of pembrolizumab in HNSCC PDX (13.38 ± 8.80 and 2.11 ± 2.34 respectively, P < 0.05; Fig. 3A) and LUSC PDX (24.00 ± 8.26 and 10.55 ± 4.47 respectively, P < 0.05; Fig. 3B). The gene discussed is CD8A; the disease is head and neck squamous cell carcinoma.