PDCD1 and head and neck squamous cell carcinoma: In immunotherapy, Lambert et al. conducted a phase I trial of Budigalimab (an anti-PD-1 agent) in head and neck squamous cell carcinoma (HNSCC) or NSCLC, finding that early changes in soluble biomarkers such as IFN-γ and CXCL9 within the first 24 h correlated positively with progression-free survival (PFS), while elevated IL-8 levels showed a negative correlation [133].