Human tissue levels and plasma pharmacokinetics of temoporfin (Foscan®, mTHPC)

A Phase I photodynamic therapy (PDT) clinical trial was carried out with Temoporfin (Foscan®, mTHPC) at the Departments of Otolaryngology at Orebro Medical Center (OMC) and Long Island Jewish Medical Center (LIJMC). A range of drug doses, consisting of 0.3, 0.15, 0.075 and 0.0375 mg kg−1, were utilized. Light treatment was performed on the sixth day after injection of the photosensitizer mTHPC. Photodynamic therapy was done on prostate cancer (six cases), bronchial cancer (one case), nasopharyngeal cancer (three cases), laryngeal cancer (eight cases), mesothelioma (one case), laryngeal papilloma (five cases) and basal cell nevus syndrome (one case). A number of patients were treated more than once. Plasma was collected and analysed at 1, 24, 48, 72, 96, 120 and 144 h and at 2 weeks post-injection, to follow the loading and clearance rate of the photosensitizer. Normal and malignant tissues were collected immediately prior to PDT, chemically extracted, and analysed for drug content spectrofluorometrically. Plasma drug levels were proportional to the dose. The half-life of the drug was 45.4 h across the entire dose range. The ratio of the drug in the tumour compared to normal adjacent mucosa was in the range of 2–3. There were no significant adverse effects. These data establish the basis for full clinical trials.