HPD PHOTODYNAMIC THERAPY

PHOTODYNAMIC THERAPY (PDT), USING HEMATOPORPHYRIN DERIVATIVE (HPD) OR ITS MORE PURIFIED FORM, DI- HEMATOPORPHYRIN-ETHER (DHE), IS PRESENTLY UNDERGOING EXTENSIVE CLINICAL TRIALS PDT IS BASED ON THE SELECTIVE RETENTION OF HPD/DHE BY NEOPLASTIC TISSUE AND ITS ABILITY TOBE PHOTODYNAMICALLY ACTIVE. THE THERAPEUTIC RESPONSE OBTAINED IS A PRODUCT OF THE HPD/DHE PRESENT IN THE TISSUE AND THE LIGHT IT ABSORBS. PHYSIOLOGICAL FACTORS SUCH AS TISSUE O2 CONTENT, PH, AND TEMPERATURE MAY ALSO PLAY A ROLE IN THE THERAPEUTIC RESPONSE. THIS PHASE I STUDY WILL DEVELOP A PROTOTYPE SINGLE OPTICAL FIBER PROBE THAT CAN MEASURE (1) THE LIGHT SPACE IRRADIANCE IN VIVO, (2) THE FLUORESCENCE OF THE HPD/DHE IN VIVO, AND (3) THE ABSORPTION DOSE RATE AND THERAPEUTIC DOSE IN VIVO. SUCH A PROBE WOULD BE USEFUL IN MONITORING THE PHOTODYNAMIC REACTION IN VIVO AND THEREBY PROVIDE FOR A MORE OPTIMUM TREATMENT. THE SYSTEM WOULD CONSIST OF A SINGLE QUARTZ FIBER FOR DELIVERY OF THE FLUORESCENCE EXCITING LIGHT AND TO PICK UP THE FLUORESCENCE SIGNAL. A RATIO OF SELECTIVE WAVELENGTHS IN THE FLUORESCENCE EMISSION WILL PERMIT SEPARATION OF HPD/DHE FLUORESCENCE FROM OTHER BACKGROUND FLUORESCENCE. IN PHASE I, EXTENSIVE PULMONARY AND ANIMAL CLINICAL TRIALS WILL BE UNDERTAKEN, ALONG WITH FURTHER REFINEMENT OF THE INSTRUMENTATION.