10199- ET-16 NEAR-INFRARED PHOTOIMMUNOTHERAPY FOR THE TREATMENT OF MALIGNANT BRAIN TUMORS

Abstract BACKGROUND Near-infrared photoimmunotherapy (NIR-PIT) is a novel intraoperative local therapy. It involves a photosensitizer a near-infrared dye (IR700) conjugated to monoclonal antibodies targeting surface antigens of cancer cells. After binding the monoclonal antibody-IR700 conjugate, irradiation with near-infrared light causes highly selective and potent cell death. METHODS AND RESULTS The antibodies used for NIR-PIT are as follows: podoplanin for malignant gliomas, SSTR2 for malignant meningiomas, and SSTR5 for GHoma. Expression of surface antigens in cell lines was confirmed by western blot and flow cytometry. We developed lasers for in vitro and in vivo assays. Time-lapse video recordings showed cell rupture and cell viability assays showed irradiation dose-dependent cytotoxicity after treatment with antibody-IR700 conjugate and near-infrared irradiation. In vivo and ex vivo studies were also performed, showing cell death. High selectivity and potency of NIR-PIT were observed, but proper penetration of light and kinetics of antibody were issues that remain to be solved. Preliminary studies confirmed that NIR-PIT is an exciting potential treatment for malignant brain tumors.