ICOS, also known as AILIM, CD278, or CVID1, promotes TCR co-stimulation and Treg cell stimulation.91 A randomized, parallel-group, phase 2/3 study with feladilimab (GSK3359609), a mAb that inhibits ICOS checkpoint, is completed in PD-L1 positive head and neck squamous cell carcinoma (NCT04128696). This evidence concerns the gene ICOS and head and neck squamous cell carcinoma.