In contrast to the approach tackling monogenic diseases, which is mostly straightforward, gene therapy for the treatment of malignment conditions needs to explore and evaluate a wide range of strategies to ensure therapeutic benefits and efficacy, such as locally delivering suicidal genes like p53 or TNF-α to elicit programmed tumor cell death, applying genetically modified oncolytic viruses to enable selective replication in cancerous cells, deploying genetically engineered immune cells to elevate antigen-mediated anti-tumor cytotoxicity, and so forth. The gene discussed is TP53; the disease is neoplasm.