PARP1 and head and neck squamous cell carcinoma: To date, pre-clinical evaluation of DNA-PK inhibitors has produced more promising results in the radiosensitization of HNSCC lines, as compared to the clinically available PARP1 inhibitors, while the combination of PARP1 and DNA-PK inhibitors has been shown to enhance HPV(−) HNSCC inhibition in both mouse xenografts and cell culture, highlighting a potential clinical application in patients with HPV(−) HNSCC [235].