TP53 and cancer: This virus and the related virus, ONYX-015, can replicate effectively in cancer cells with a dysfunctional (absent or mutated) p53 tumor suppressor gene.10 Further studies have indicated that late viral RNA export, rather than p53 replacement, determines ONYX-015 tumor selectivity.11 Currently, H101 is approved only in China for patients with advanced nasopharyngeal cancer.9,10