A Test of Different Photosensitizers for Photodynamic Treatment of Cancer in a Murine Tumor Model

The efficiency of different sensitizers for photodynamic therapy (PDT) was tested using a model system with a C3H mammary carcinoma growing subcutaneously on the dorsal side of mouse feet. Growth curves were constructed from which growth delay and doubling time in the regrowth phase were calculated. As PDT induced oedema in the mouse foot, this model system also allowed assessment of normal tissue response. The following sensitizers were tested: hematoporphyrin derivative (HpD), Photofrin II (PII), tetraphenylporphinetetrasulfonate (TPPS 4 ), acridine orange (AO), phthalocyanine tetrasulfonate (PCTS), Al‐ and Zn‐phthalocyanine tetrasulfonate (A1PCTS and ZnPCTS). For tumor control, the following sensitizer efficiencies were found: PII > HpD > AIPCTS > TPPS 4 >>> ZnPCTS, PCTS, AO. With regard to sensitizing normal‐tissue damage: PII > AIPCTS, TPPS 4 > HpD, ZnPCTS, PCTS. The results suggest that AIPCTS should be further evaluated for use in PDT.