demonstrated that adenosine deaminase (ADA), responsible for deaminating immunosuppressive adenosine to inosine, increases CD4+ effector T cells’ sensitivity to inhibitory signals transmitted by adenosine receptors in HNSCC patients, leading to extracellular adenosine accumulation and affecting the tumor microenvironment (52). The gene discussed is ADA; the disease is head and neck squamous cell carcinoma.