Tierexperimentelle Untersuchungen zur Photodynamischen Therapie des Prostatakarzinoms mit 5-Aminolävulinsäure induziertem Protoporphyrin IX an einem Ratten-Tumor-Modell

OBJECTIVE: In order to expand the use of photodynamic therapy (PDT)
in the treatment of prostate carcinoma (PCA), the aim of this study
was to evaluate PDT by means of 5-aminolevulinic acid
(5-ALA)-induced protoporphyrin IX (PPIX) in an in vivo tumor model.
METHODS: The model used was the Dunning R3327 tumor. First of all,
the pharmacokinetics and the localization of PPIX were obtained
using fluorescence measurement techniques. Thereafter, PDT using
150 mg 5-ALA/kg b.w. i.v. was performed by homogenous irradiation
of the photosensitized tumor (diode laser lambda = 633 nm). The
tumors were resected 2 days post-PDT and the extent of the necrosis
was determined histopathologically. RESULTS: The kinetics of PPIX
fluorescence revealed a maximum intensity in the tumor tissue
within 3 and 4.5 h post-application of 5-ALA. At this time,
specific PPIX fluorescence could be localized selectively in the
tumor cells. The PDT-induced necrosis (n = 18) was determined to be
94 +/- 12% (range 60-100%), while the necrosis of the controls (n =
12) differs significantly (p < 0.01), being less than 10%.
CONCLUSION: These first in vivo results demonstrate the effective
potential of 5-ALA-mediated PDT on PCA in an animal model.