Gene therapy works by replacing defective genes with normal ones and therapeutic drugs are usually administered through viral vectors or genetically engineered microorganisms.1 Recombinant Adenovirus human p53 (rAd-p53) (GendicineTM) was approved by the China Food and Drug Administration (FDA) in 2003, becoming a worldwide first-line drug for the treatment of head and neck squamous cell carcinoma (HNSCC).2 However, a similar virus (Advexin, Introgen) failed to receive US FDA approval in 2008. This evidence concerns the gene TP53 and head and neck squamous cell carcinoma.