Bronchoscopic photodynamic diagnosis and therapy for lung cancer

Photodynamic Therapy of Non-Small Cell Lung Cancer. Narrative Review and Future Directions

Photodynamic therapy (PDT) is an established treatment modality for non-small cell lung cancer. Phototoxicity, the primary adverse event, is expected to be minimized with the introduction of new photosensitizers that have shown promising results in phase I and II clinical studies. Early-stage and superficial endobronchial lesions less than 1 cm in thickness can be effectively treated with external light sources. Thicker lesions and peripheral lesions may be amenable to interstitial PDT, where the light is delivered intratumorally. The addition of PDT to standard-of-care surgery and chemotherapy can improve survival and outcomes in patients with pleural disease. Intraoperative PDT has shown promise in the treatment of non-small cell lung cancer with pleural spread. Recent preclinical and clinical data suggest that PDT can increase antitumor immunity. Crosslinking of signal transducer and activator of transcription-3 molecules is a reliable biomarker to quantify the photoreaction induced by PDT. Randomized studies are required to test the prognosis value of this biomarker, obtain approval for the new photosensitizers, and test the potential efficacy of interstitial and intraoperative PDT in the treatment of patients with non-small cell lung cancer.

Photodynamic effects of mTHPC on human colon adenocarcinoma cells: photocytotoxicity, subcellular localization and apoptosis

The photodynamic properties of meta-tetra(hydroxyphenyl)chlorin (mTHPC), a promising second-generation photosensitizer, were investigated using a human colon adenocarcinoma cell line (Colo 201 cells). The study on photocytotoxicity using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay showed that mTHPC was an effective photosensitizer on Colo 201 cells. The photocytotoxicity of mTHPC showed both drug and light dose-dependent characteristics. To reach LD50, namely, the dose at which 50% of the cells were killed, only 0.45+/-0.15 microg/mL of mTHPC and 3 J/cm2 of light dose were required. The presence of 10% fetal calf serum in culture medium significantly decreased the incorporation of mTHPC into cells and resulted in the reduction of photodynamic efficacy. Using confocal laser scanning microscopy, mTHPC was first shown to localize in lysosomes rather than in mitochondria. Furthermore, nuclear stainings demonstrated that photodynamic therapy with mTHPC induced apoptosis in Colo 201 cells.