Photodynamic therapy using a second generation photosensitizer, Talaporfin

Abstract

Photodynamic therapy (PDT) using Talaporfin is an attractive treatment for central-type early lung cancer. It was noted that some patients had altered levels of arterial oxygen saturation as indicated by pulse oximeter (SpO2) and arterial oxygen saturation levels in blood gas analysis (SaO2) during PDT. The present experiments were designed to provide an explanation for these findings. The influence of Talaporfin on SpO2 using in vitro and in vivo experiments, and clinically, was examined. Our in vitro and in vivo experiments showed a linear relationship between Talaporfin concentration in the plasma and the SpO2 level (R=0.9957 and 0.9837). The apparent SpO2 level decreased according to the increase of Talaporfin concentration in the plasma. In two patients with PDT, SpO2 levels at 4-6h and 24h after Talaporfin administration were 93% and 97%, respectively. Talaporfin raised blood absorbance at 660nm with a pulse oximeter. It appeared that the presence of the drug falsely decreased the level of SpO2 since SpO2 did not actually change.