Skin fluorescence following photodynamic therapy with NPe6 photosensitizer

The second-generation photosensitizer NPe6 has strong anti-tumor effects with a much shorter photosensitive period than the first-generation photosensitizer Photofrin. Although photosensitive period has been reduced, skin photosensitivity is still a major side effect of photodynamic therapy (PDT). Therefore, we conducted a prospective study to investigate whether the NPe6 fluorescence intensity in skin after PDT could be measured effectively in human patients to improve the management of a patient's photosensitive period.

The NPe6 fluorescence measurements using a constructed fluorescence sensing system at the inside of the arm were acquired prior to and 5 and 10min after NPe6 administration as well as at the time of PDT (4-5h after administration), at discharge (2 or 3days after PDT), and at 1 or 2 weeks after PDT. Participants were interviewed as to whether they had any complications at 2 weeks after PDT.

Nine male patients and one female patient entered this study. Nine patients were inpatients and one patient was an outpatient. All of the measurements of NPe6 fluorescence in the skin could be obtained without any complications. The spectral peak was detected at the time of discharge (2-3days after administration) in most cases and it decreased at 1 or 2 weeks after PDT.

The fluorescence of NPe6 in the skin could be detected feasibly using the fluorescence sensing system in human patients. Measuring the relative concentration of NPe6 in the skin indirectly by measuring fluorescence intensity might be useful to predict the period of skin photosensitivity after PDT.