ATR and head and neck squamous cell carcinoma: Recent developments uncovered highly potent small molecules against ATR and DNA-PK, and clinical trials are conducted in HNSCC with these inhibitors both as single agent and in combination (Table 1; ATR: NCT04576091, NCT04491942; DNA-PK: NCT04533750, NCT01353625) [48,111,177,193,194].