Photodynamic therapy with redaporfin activated by pulsed laser light

Significance Redaporfin is a photosensitizer under clinical trials for head and neck cancer. In previous work, a continuous light source was used in several tumor models, either in vitro or in vivo. However, the use of pulsed light (PL) sources can bring advantages to photodynamic therapy, such as higher penetration depths. Approach To study the influence of the light source in the efficacy of redaporfin-PDT, balb/c mice were inoculated with subcutaneous CT26 tumors. Redaporfin was activated using a PL source at 750 nm, with a repetition rate of 20 Hz and an energy per pulse of 24 mJ/cm2. Illumination time ranged from 5 to 15 min. Results The results show an acute inflammatory response followed by a fast shrinkage and necrosis of the tumors and no significant side effects. Conclusions The activation of redaporfin with PL leads to good response of the tumors and further studies are being held to optimize the treatment conditions.