Wulf Hans Christian, Heerfordt Ida M, Philipsen Peter Alshede
Department of Dermatology, Copenhagen University Hospital Bispebjerg, 2400 Copenhagen NV, Denmark.
Pharmaceuticals (Basel). 2021 Apr 6;14(4):333. doi: 10.3390/ph14040333.
Photodynamic therapy (PDT) with methyl aminolevulinate (MAL) is a popular treatment for actinic keratoses (AK), and several PDT treatment modalities with similar cure rates are in use. The effect relies on the activation of protoporphyrin IX (PpIX) in premalignant cells. This study aimed to measure PpIX during each treatment modality to determine the minimal PpIX activation and shortest exposure time for optimal cure rate. In four different treatment modalities, we established the PpIX formation up to three hours after MAL application without illumination and measured the speed of PpIX photoactivation during 9 min of red light (37 J/cm). The level of PpIX three hours after MAL application was set to 100 PpIX units. In comparison, 85 PpIX units were formed during daylight PDT, 57 PpIX units during pulse PDT, and 52 PpIX units without any curettage prior to MAL. The activation of 50 PpIX units should, therefore, be enough to obtain a full effect on AK. Further, red light illumination may be shortened from 9 min to 1-2 min. The results indicate that PDT can be performed successfully with half the illumination time used in daylight PDT today and with one fourth of the illumination time used in classical PDT.
使用甲基氨基酮戊酸（MAL）的光动力疗法（PDT）是治疗光化性角化病（AK）的常用方法，目前有几种治愈率相似的PDT治疗方式在使用。其疗效依赖于癌前细胞中原卟啉IX（PpIX）的激活。本研究旨在测量每种治疗方式下的PpIX，以确定实现最佳治愈率所需的最小PpIX激活量和最短照射时间。在四种不同的治疗方式中，我们在未光照的情况下测定了MAL应用后三小时内PpIX的形成情况，并测量了9分钟红光（37 J/cm）照射期间PpIX的光激活速度。将MAL应用后三小时的PpIX水平设定为100 PpIX单位。相比之下，日光PDT过程中形成了85 PpIX单位，脉冲PDT过程中形成了57 PpIX单位，在MAL应用前未进行任何刮除的情况下形成了52 PpIX单位。因此，50 PpIX单位的激活量应该足以对AK产生完全疗效。此外，红光照射时间可从9分钟缩短至1 - 2分钟。结果表明，PDT可以成功进行，所用照射时间仅为当今日光PDT的一半，以及传统PDT的四分之一。
