Since 4-nitroquinoline 1-oxide (4NQO)-induced premalignant oral lesions and oral cancer share expression of a number of tumor antigens [31], studies were conducted to determine if treating premalignant lesion-bearing mice with PD-1 antibody would stimulate reactivity of their lymph node cells to an in vitro challenge of premalignant lesions or HNSCC. This evidence concerns the gene PDCD1 and lip and oral cavity carcinoma.