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Photodynamic therapy (PDT) can not only directly eliminate cancer cells, but can also stimulate antitumor immune responses. It also affects the expression of immune checkpoints. The purpose of this review is to collect, analyze, and summarize recent news about PDT and immune checkpoints, along with their inhibitors, and to identify future research directions that may enhance the effectiveness of this approach. A search for research articles published between January 2023 and March 2024 was conducted in PubMed/MEDLINE. Eligibility criteria were as follows: (1) papers describing PDT and immune checkpoints, (2) only original research papers, (3) only papers describing new reports in the field of PDT and immune checkpoints, and (4) both in vitro and in vivo papers. Exclusion criteria included (1) papers written in a language other than Polish or English, (2) review papers, and (3) papers published before January 2023. 24 papers describing new data on PDT and immune checkpoints have been published since January 2023. These included information on the effects of PDT on immune checkpoints, and attempts to associate PDT with ICI and with other molecules to modulate immune checkpoints, improve the immunosuppressive environment of the tumor, and resolve PDT-related problems. They also focused on the development of new nanoparticles that can improve the delivery of photosensitizers and drugs selectively to the tumor. The effect of PDT on the level of immune checkpoints and the associated activity of the immune system has not been fully elucidated further, and reports in this area are divergent, indicating the complexity of the interaction between PDT and the immune system. PDT-based strategies have been shown to have a beneficial effect on the delivery of ICI to the tumor. The utility of PDT in enhancing the induction of the antitumor response by participating in the triggering of immunogenic cell death, the exposure of tumor antigens, and the release of various alarm signals that together promote the activation of dendritic cells and other components of the immune system has also been demonstrated, with the result that PDT can enhance the antitumor immune response induced by ICI therapy. PDT also enables multifaceted regulation of the tumor’s immunosuppressive environment, as a result of which ICI therapy has the potential to achieve better antitumor efficacy. The current review has presented evidence of PDT’s ability to modulate the level of immune checkpoints and the effectiveness of the association of PDT with ICIs and other molecules in inducing an effective immune response against cancer cells. However, these studies are at an early stage and many more observations need to be made to confirm their efficacy. The new research directions indicated may contribute to the development of further strategies.

Photodynamic therapy (PDT) is a minimally invasive therapeutic method with high selectivity of action. It has gained great popularity in recent years as a new therapy for the treatment of cancer, but is also used in dermatology, ophthalmology, and antimicrobial treatment, among others. The therapeutic regimen involves the administration of a photosensitizer (PS) that selectively accumulates in tumor cells or is present in the blood vessels of the tumor prior to irradiation with light at a wavelength corresponding to the absorbance of the photosensitizer, leading to the generation of reactive oxygen species (ROS). Choosing the right PS is one of the most important steps in PDT and is crucial to the effectiveness of the therapy. Despite the many compounds discovered, the search for new molecules that could fulfill the functions of an optimal photosensitizer and improve the efficiency of PDT is still ongoing. Compounds of natural origin could contribute to achieving this goal. A number of photoactive substances as effective as synthetic photosensitizers have been described in various plant and fungal species. With the increasing identification of photoactive natural products, many new photosensitizers are expected to emerge. Some have already been clinically tested with promising results. In our work, we provide insights into this research and molecules, analyze their advantages and disadvantages, and point out gaps in current knowledge and future directions for their development. We also present natural photosensitizers not yet tested in clinical trials and point out future potential directions for their development.

Research on the development of photodynamic therapy for the treatment of brain tumors has shown promise in the treatment of this highly aggressive form of brain cancer. Analysis of both in vivo studies and clinical studies shows that photodynamic therapy can provide significant benefits, such as an improved median rate of survival. The use of photodynamic therapy is characterized by relatively few side effects, which is a significant advantage compared to conventional treatment methods such as often-used brain tumor surgery, advanced radiotherapy, and classic chemotherapy. Continued research in this area could bring significant advances, influencing future standards of treatment for this difficult and deadly disease.