Progress in Clinical Trials of Photodynamic Therapy for Solid Tumors and the Role of Nanomedicine

Simple Summary Photodynamic therapy (PDT) has been undertaken with growing focus in recent studies to identify successful anticancer therapies. The field of PDT has evolved rapidly and is continuously being evaluated with new techniques. To make PDT more active and selective, molecular strategies are being developed. In the latest clinical studies on the use of PDT, some challenges are presented. Therefore, the use of nanotechnology-based approaches as delivery tools for PSs may improve their cancer cellular uptake and their toxic properties, as well as the PDT's therapeutic impact. In addition, photoimmunotherapy (PIT) and photothermal therapy (PTT) might have a significant impact on solid tumor therapeutic strategies. Current research to find effective anticancer treatments is being performed on photodynamic therapy (PDT) with increasing attention. PDT is a very promising therapeutic way to combine a photosensitive drug with visible light to manage different intense malignancies. PDT has several benefits, including better safety and lower toxicity in the treatment of malignant tumors over traditional cancer therapy. This reasonably simple approach utilizes three integral elements: a photosensitizer (PS), a source of light, and oxygen. Upon light irradiation of a particular wavelength, the PS generates reactive oxygen species (ROS), beginning a cascade of cellular death transformations. The positive therapeutic impact of PDT may be limited because several factors of this therapy include low solubilities of PSs, restricting their effective administration, blood circulation, and poor tumor specificity. Therefore, utilizing nanocarrier systems that modulate PS pharmacokinetics (PK) and pharmacodynamics (PD) is a promising approach to bypassing these challenges. In the present paper, we review the latest clinical studies and preclinical in vivo studies on the use of PDT and progress made in the use of nanotherapeutics as delivery tools for PSs to improve their cancer cellular uptake and their toxic properties and, therefore, the therapeutic impact of PDT. We also discuss the effects that photoimmunotherapy (PIT) might have on solid tumor therapeutic strategies.