Photothermal hydrogels for cancer immunotherapy: mechanisms, multifunctional designs, and intelligent optimization toward precision therapy

Immunotherapy has demonstrated significant advantages owing to its enhanced tumor cell-killing efficacy and reduced side effects. However, key issues such as low immunogenicity of tumors, inhibitory tumor microenvironment, and poor drug targeting still limit the efficacy of immunotherapy. Against these problems, photothermal hydrogels, as a new type of treatment platform, have been introduced into the field of tumor immunotherapy. They possess functionally tunable mechanochemical properties and efficient photothermal conversion ability, which provide a highly potential innovative path to break through the current bottlenecks in tumor immunotherapy. In this review, we systematically summarize recent advances in photothermal hydrogel-based strategies for cancer immunotherapy. We focus on their critical roles in remodeling the immunosuppressive tumor microenvironment, inducing ICD, enabling targeted delivery of immunomodulatory agents, preventing postoperative metastasis and recurrence, and facilitating the development of personalized cancer vaccines. In addition, we discuss key challenges associated with clinical translation, including dose control, long-term fate and degradation, and reproducibility, as well as emerging opportunities enabled by AI–guided optimization. Overall, this review highlights photothermal hydrogels as a promising drug delivery and therapeutic platform with the potential to improve the efficacy and safety of cancer immunotherapy and to accelerate its translational application.