As such, there has not yet been a clinical trial performed investigating responses to anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody immunotherapy, with or without radiotherapy, in canine OSCC, so comparisons of response with human OSCC or HNSCC are not possible at this time. Here, CTLA4 is linked to head and neck squamous cell carcinoma.