Ta. Katsumi et al., PHOTODYNAMIC THERAPY WITH A DIODE-LASER FOR IMPLANTED FIBROSARCOMA INMICE EMPLOYING MONO-L-ASPARTYL CHLORIN E(6), Photochemistry and photobiology, 64(4), 1996, pp. 671-675
The authors performed photodynamic therapy (PDT), avoiding any hyperth
ermic effects, using a newly developed diode laser and photosensitizer
, mono-L-aspartyl chlorin e(6) (NPe6), of Meth-A fibrosarcoma implante
d in mice and achieved tumor therapeutic benefit. The photodynamic lig
ht treatment was performed 5 h following the photosensitizer administr
ation. With 5.0 mg/kg NPe6 and light doses of 50, 100, 150 and 200 J/c
m(2), the tumor cure rates were 20, 50, 70 and 90%, respectively. With
100 J/cm(2) laser exposure and NPe6 doses of 1.25, 2.5, 5.0, 7.5 and
10.0 mg/kg, the tumor cure rates were 0, 20, 50, 70 and 90%, respectiv
ely. A charge-coupled device (CCD) camera system was employed to measu
re the NPe6 fluorescence intensity correlating with the residual amoun
t of the photosensitizer at deferent depth from the tumor surface. The
ratios of the NPe6 fluorescence intensity at 3 mm from the tumor surf
ace following 50, 100, 150 and 200 J/cm(2) laser exposure to no laser
exposure were 0.73, 0.36, 0.22 and 0.16, respectively. With samples se
ctioned at 1 mm depth, after 50 J/cm(2) and the same photosensitizer d
ose (5 mg/kg) this ratio was 0.19. These results suggest that a certai
n increase in the tumor tissue level of NPe6 and a certain increase of
laser light dose reaching deeper layers of tumor caused an increase i
n percent cure. In addition, the effectiveness of PDT depends on the t
otal laser dose reaching deeper layers of tumors. Furthermore, the eff
ectiveness of PDT tends to correlate with the amount of NPe6 photoblea
ching by PDT.