Exosome-Enhanced Sonodynamic Therapy in Cancer: Emerging Synergies and Modulation of the Tumor Microenvironment

The development of safer, more effective, and tumor-specific therapeutic strategies remains a major challenge in oncology. Conventional treatments such as chemotherapy and radiotherapy often cause severe side effects and are limited in their ability to target deep-seated or resistant tumors. In this context, sonodynamic therapy (SDT) has emerged as a promising, non-invasive option, harnessing low-intensity ultrasound to activate sonosensitizers deep within tissues and generate cytotoxic reactive oxygen species (ROS) that selectively induce cancer cell death. Interestingly, SDT can also be combined with other therapies to achieve synergistic effects. However, despite encouraging preclinical results, SDT clinical translation is hindered by the poor aqueous solubility, instability, and low tumor specificity of traditional sonosensitizers. To overcome these limitations, recent studies have focused on employing extracellular vesicles (EVs), especially exosomes, as natural, biomimetic nanocarriers for sonosensitizer delivery. EVs offer unique advantages, including high biocompatibility, low immunogenicity, and intrinsic tumor-targeting ability, which make them ideal platforms for improving the therapeutic precision of SDT. Although several delivery strategies have been proposed, a comprehensive and focused overview of approaches specifically designed to enhance SDT performance using EVs is currently lacking. This review summarizes recent advances in integrating EVs with SDT for cancer treatment. It discusses the mechanisms underlying SDT, the engineering strategies developed to enhance exosome functionality, and the synergistic effects achieved through this combination. Furthermore, this review emphasizes that EV-based SDT not only enhances tumor accumulation of the therapeutic nanoplatforms, but also actively remodels the tumor microenvironment by improving oxygen availability, reversing immunosuppressive conditions, and triggering durable antitumor responses. Finally, the review addresses the translational challenges and outlines the critical future directions required to advance this promising therapeutic approach toward clinical application.