Here, we compared the radiosensitization through xevinapant with two other emerging approaches, the inhibition of ATR and PARP through tuvusertib and olaparib, in a panel of four radioresistant HPV-negative HNSCC cell lines (HSC4, UT-SCC-60A, SAS, SAT). Here, ATR is linked to head and neck squamous cell carcinoma.