A. Segalla et al., CGP 55398, A LIPOSOMAL GE(IV) PHTHALOCYANINE BEARING 2 AXIALLY LIGATED CHOLESTEROL MOIETIES - A NEW POTENTIAL AGENT FOR PHOTODYNAMIC THERAPY OF TUMORS, British Journal of Cancer, 69(5), 1994, pp. 817-825
Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moie
ties was prepared by chemical synthesis and incorporated in a monomeri
c state into small unilamellar liposomes (CGP 55398). Upon photoexcita
tion with light wavelengths around its intense absorption peak at 680
nm, GePc shows an efficient photosensitising activity towards biologic
al substrates through a mechanism which largely involves the intermedi
acy of singlet oxygen. GePc injected systemically into mice bearing an
intramuscularly implanted MS-2 fibrosarcoma is quantitatively transfe
rred to serum lipoproteins and localises in the tumour tissue with goo
d efficiency: at 24 h post injection the GePc content in the tumour is
0.74 and 1.87 mu g per g of tissue with a tumour/peritumoral ratio of
4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg(-1) respectiv
ely. At this time the red-light irradiation of the GePc-loaded fibrosa
rcoma causes a fast and massive tumour necrosis involving both maligna
nt cells and blood vessels.