Photodynamic therapy of prostate cancer by means of 5-aminolevulinic acid-induced protoporphyrin IX - In vivo experiments on the dunning rat tumor model

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 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 B 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. Copyright (C) 2004 S. Karger AG, Basel.