Ultrasound-mediated immune regulation in tumor immunotherapy

Cancer immunotherapy, which enhances the body's immune response and inhibits immune escape to eliminate or combat tumors, holds great promise for cancer treatment. However, it still faces many challenges, such as low response rate and immune-related adverse events, which limit its clinical applications. Ultrasound, as a safe, effective and non-invasive technique, has been widely used in diagnostics and therapeutics of tumors. In recent years, many studies have confirmed that ultrasound can also mediate tumor immunotherapy. High intensity focused ultrasound can destroy tumor tissue and lead to the in situ production of tumor fragments at the same time, which can be used as antigens of the immune system to form in situ vaccines to induce a systemic immune response. The ultrasound-targeted microbubble destruction technique with microbubbles as the carrier mediates the targeted delivery of immunomodulatory adjuvants to tumor cells or immune cells. It can not only enhance the host immune response and improve immunotherapy efficacy, but also reduce the dosage of immunoregulatory adjuvants and side effects. Sonodynamic therapy can induce immunogenic cell death to elicit an immune response and the combination with immunotherapy can achieve higher therapeutic efficacy. In this review, research advances in ultrasound-mediated tumor immunotherapy are summarized, and the potential and challenges of its application are discussed.