The biological essence of synthetic lethality: Bringing new opportunities for cancer therapy

Abstract Synthetic lethality (SL), a genetic concept, has revolutionized the development of antitumor therapies by providing avenues to target previously “undruggable” targets with enhanced specificity for tumor cells over normal tissue. The principles of SL have expanded beyond genetic definitions to encompass biological functions, including genome stability, cell cycle regulation, cell death mechanisms, cellular metabolism, cell–cell interactions, and the tumor microenvironment (TME). Tumor cells with inactivated survival pathways are sensitive to therapeutic inhibition of compensatory mechanisms, while normal cells remain unaffected. Exploiting SL based on functional contexts has the potential to significantly improve cancer patient survival by reducing resistance to targeted therapies and enhancing antitumor efficacy when combined with other treatment modalities. This review explores the underlying mechanisms of synthetic lethality interactions (SLI) characterized by biological functions in individual cancer cells and the TME. We also provide a comprehensive summary of strategies for leveraging the dynamic nature of SLI to overcome therapeutic resistance. Additionally, we discuss various approaches and models for screening and designing potent SL agents tailored to the specific needs of cancer patients, as well as strategies for combining SL drugs in tumor treatment. This review offers valuable insights into harnessing SL as a promising avenue for precision cancer therapy.