TP53 and head and neck squamous cell carcinoma: Phosphorylation of its downstream effectors pS6 and pAKT (S473) was observed to be inhibited.37 RAD001 also prevented tumor growth of cells with HPV-negative TP53 mutation in vivo through autophagy activity.317 The novel mTOR inhibitors CZ415, AZD8055, OSI-027 (ASP4876), and CC-223 monotherapy inhibited HNSCC cell growth in vivo.318–320 mTOR monotherapy and combination with other treatment regimens all demonstrated promising effects on the HNSCC xenograft model.