Interstitial photodynamic therapy in the canine prostate with disulfonated aluminum phthalocyanine and 5-aminolevulinic acid-induced protoporphyrin IX.
BACKGROUND
Photodynamic therapy (PDT) is an experimental approach for treating prostate cancer localized to the gland that does not involve surgery or irradiation. Second-generation photosensitizers 5-aminolevulinic acid (ALA) and aluminum disulfonated phthalocyanine (AlS2Pc) were studied in the normal canine prostate.


METHODS
Tissue biodistribution of photosensitizers on serial biopsies was examined using fluorescence microscopy. Photodynamic therapy was done by delivering red light interstitially at 100 mW through fibers placed under transrectal ultrasound guidance.


RESULTS
Peak levels of AlS2Pc appeared at 5-24 hr and at 3 hr for ALA. Macroscopic PDT lesions were up to 12 mm in diameter using AlS2Pc, but only 1-2 mm with ALA. Light at 300 mW caused thermal lesions. At 28 days, damaged glands remained atrophic, but the interlobular supporting stroma was well-preserved. Urethral lesions healed by 28 days without functional impairment.


CONCLUSIONS
Although the results with ALA were disappointing, PDT using AlS2Pc looks like a promising modality for treatment of localized prostate cancer.
Chang
S C
SC
Department of Surgery, University College London Medical School, UK.
Buonaccorsi
G A
GA
MacRobert
A J
AJ
Bown
S G
SG
D000622:Aminolevulinic Acid / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D001284:Atrophy; D003094:Collagen / Q000032:analysis; D004285:Dogs; D007211:Indoles / Q000493:pharmacokinetics / Q000494:pharmacology*; D007834:Lasers; D008027:Light; D008297:Male; D009942:Organometallic Compounds / Q000493:pharmacokinetics / Q000494:pharmacology*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D011467:Prostate / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000188:drug therapy; D011524:Protoporphyrins / Q000378:metabolism*
D007211:Indoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D011524:Protoporphyrins; C064331:aluminum phthalocyanine disulfonate; D000622:Aminolevulinic Acid; D003094:Collagen; C028025:protoporphyrin IX