TP53 and head and neck squamous cell carcinoma: In 2003, China became the first country to approve this p53 adenovirus-based gene therapy drug (Gendicine) to be marketed for the treatment of human head and neck squamous cell carcinoma.40, 41, 42 This rAd-p53 is a weakened adenovirus that binds to the coxsackie-and-adenovirus receptor on tumor cells and penetrates cells selectively through receptor-mediated endocytosis, which may result in intracellular overexpression of wild-type p53, leading to p53-mediated tumor regression.43