Photochemotherapy of experimental colonic tumours with intra-tumorally applied methylene blue.
BACKGROUND
Phototoxicity of intra-tumoral injected methylene blue (MB+) was studied in 48 experimental colonic tumours in comparison with photosan-3, Zn-phthalocyanine and tetrasulphanated ClAl-phthalocyanine.


METHODS
In mice. xenotransplanted subcutaneous tumours about 1 cm in diameter were treated photodynamically twice, with different sensitisers. The irradiation was performed at the sensitiser-specific wavelength, and a density of 100 mW/cm2 and a dose of 100 J/cm2.


RESULTS
Light alone without sensitiser did not induce any effect in mice tumours. Surprisingly, Al-phthalocyanine could only be used for intratumoral injections because of toxic effects after intravenous applications in nude mice. Using MB+ (1%), 75% of the tumours were destroyed by a single photodynamic treatment (PDT). In addition, toxicity of MB+ was most intense when compared with Zn-phthalocyanine and photosan-3. However, after the second PDT, there was no statistically significant difference among these sensitisers. Dark toxicity of MB+ (1%) could be well demonstrated by sufficient sensitiser incorporation without irradiation, which led to a stationary tumour volume up to 3 weeks after injection.


CONCLUSIONS
Intra-tumoral MB+ PDT is a potential treatment for inducing necrosis in vivo. With regard to tumour tissue, the selectivity of MB+ is high and depends on a precise local injection of the dye.
Department of General Surgery (Chirurgische Klinik I), University of Ulm, Germany.
K
K
Orth
D
D
Russ
G
G
Beck
A
A
Rück
H G
HG
Beger
D000818:Animals; D003110:Colonic Neoplasms / Q000188:drug therapy*; D005260:Female; D006415:Hematoporphyrins; D007211:Indoles / Q000008:administration & dosage; D015552:Injections, Intralesional; D054833:Isoindoles; D008751:Methylene Blue / Q000008:administration & dosage*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009942:Organometallic Compounds / Q000008:administration & dosage; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D017967:Zinc Compounds
D006415:Hematoporphyrins; D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D017967:Zinc Compounds; C052736:chloroaluminum tetrasulfophthalocyanine; C071875:photosan III; C052159:Zn(II)-phthalocyanine; D008751:Methylene Blue