Apart from that, HNSCC cells can respond to cetuximab treatment with recruitment of CD4+, FOXP3+ intra-tumoral T regs expressing CTLA-4, CD39, and TGFβ, which results in suppression of cetuximab-mediated antibody-dependent cellular cytotoxicity (ADCC) and poor prognosis [19]. Here, CTLA4 is linked to head and neck squamous cell carcinoma.