Trained immunity: A new player in cancer immunotherapy

In the past, immune memory was considered an exclusive feature of the adaptive immune system. However, accumulating evidence suggests that the innate immune system, the most primitive and fundamental component of immunity, can mount more robust responses to non-specific stimuli following prior exposure to different types of initial stimuli, a phenomenon known as trained immunity. Trained immunity has been extensively studied in diverse disease contexts, including infectious diseases, autoimmune disorders, and chronic inflammatory conditions. Notably, significant advancements have been made in recent years in understanding the roles and therapeutic potential of trained immunity in oncology. This review aims to explore the multifaceted roles of trained immunity across different cancer types, providing a comprehensive summary of the pertinent stimuli and associated molecular mechanisms. Additionally, we evaluate the clinical applications of various trained immunity stimuli in cancer therapy and offer perspectives on future directions for integrating trained immunity into cancer treatment strategies.