Therapeutic effect of interstitial photodynamic therapy using ATX-S10(Na) and a diode laser on radio-resistant SCCVII tumors of C3H/He mice.

We examined the effect of interstitial photodynamic therapy (PDT) with a new photosensitizer ATX-S10(Na). This photosensitizer showed the strongest therapeutic effect 2-4 h after administration and was rapidly excreted from individual organs except tumor and liver 24 h after i.v. injection. Microscopic histofluorescent imaging showed fluorescence of ATX-S10(Na) in the cytoplasm of the tumor cells, but not in nuclei and in the vascular wall. Irradiation of Liniac 30 Gly+20 Gly slightly reduced the tumor size, but all mice died of relapse within 60 days after irradiation. In the PDT group, all tumors became non-palpable and healing was achieved in 50% of mice 120 days after PDT.