HYPERICIN - A NEW LASER PHOTOTARGETING AGENT FOR HUMAN CANCER-CELLS

Laser activation of anthracycline-related drugs combines chemotherapy with photoablation for improved treatment. Hypericin, a structurally r elated anthraquinone, was tested for laser activation and cytotoxicity in human cancer cells. Viability of P3 squamous cell carcinoma cells incubated with 1 to 20 mu g/mL hypericin was reduced by more than 95% after 1 minute exposure at 4 degrees C to an argon laser (514 nm, 5 W) , a KTP-532 laser (532 nm, 5 W), or a 20-A xenon lamp. Viability was r educed over 90% in six human carcinoma, sarcoma, and melanoma cell lin es by this combined treatment, but only trace toxicity was seen after separate exposure to hypericin or light alone. These results show that hypericin is a sensitive agent for phototherapy of human cancer cells in vitro and indicate that this drug may be useful for tumor targetin g via minimally invasive imaging-guided laser fiberoptics.