Using the PARP inhibitor niraparib (1 μmol/L), this was recently shown to equally increase the sensitivity of two HPV-positive and two HPV-negative HNSCC cell lines to conventional radiation (DER = 1.06-1.21) and proton irradiation (DER = 1.12-1.31)[55]. The gene discussed is PARP1; the disease is head and neck squamous cell carcinoma.