TUMOR-LOCALIZING AND TUMOR-PHOTOSENSITIZING PROPERTIES OF ZINC(II)-OCTAPENTYL-PHTHALOCYANINE

Zn(II)-octapentyl-phthalocyanine (ZnOPPc), incorporated into a Cremoph or oil emulsion, was found to be a highly selective tumour-targeting a gent (50-fold larger concentration in the tumour than in the peritumor al tissue) when injected at a dose of 1.46 mu mol (kg body weight)(-1) in Balb/c mice bearing an intramuscularly transplanted MS-2 fibrosarc oma. The pharmacokinetic properties of this phthalocyanine were closel y similar to those found for the analogous octadecyl derivative, where as the unsubstituted Zn(II)-phthalocyanine showed a lower efficiency a nd selectivity of tumour targeting than the octaalkyl-substituted phth alocyanines. Irradiation of the ZnOPPc-loaded tumour with 620-700 nm l ight 24 h after injection caused a significant delay of tumour growth with a gradual shrinkage of the neoplastic mass; the damage involved i mportant contributions from both random necrosis and apoptosis of mali gnant cells. (C) 1997 Elsevier Science S.A.