PD-1 inhibitor naive patients with advanced HNSCC (n=41) or NSCLC (n=40) received budigalimab intravenously...best overall response of 15% in HNSCC and 18% in NSCLC was observed in all treated patients....Univariate analysis demonstrated an association between prolonged progression-free survival and higher tumor mutational burden/neoantigen load, smaller tumor size, lower platelet-lymphocyte ratios, lower CCL23, lower colony-stimulating factor 1, and lower interleukin-6 levels at baseline....The biomarker analysis presented herein identified additional early pharmacodynamic biomarkers associated with anti–PD-1 activity and improved clinical responses to budigalimab in patients with advanced HNSCC and NSCLC.