CD4 and head and neck squamous cell carcinoma: Immunotherapy using 4-1BB is being developed for a better way of treating HNSCC, in which it is proposed to activate the anticancer immune response cells, B cells, CD4+ T cells, and CD8 + T cells, and suppress the oncogenes.23The mechanism of agonistic anti-4-1BB stimulates and activates immune cells by binding with 4-1BB receptors on TILs and increasing proliferation of TILs, resulting in upregulation of an active immune response against the cancer cells.