Interstitial Photodynamic Therapy and Glioblastoma: Light Fractionation Study on a Preclinical ModelThérapie photodynamique interstitielle et glioblastome : étude préclinique du fractionnement

Séance du mercredi 01 avril 2015 (CHIRURGIE ONCOLOGIQUE INTERVENTIONNELLE)

Résumé

Background: Glioblastoma is a high-grade cerebral tumor with local recurrence and poor outcome. Photodynamic therapy (PDT) is a local treatment based on the light activation of a photosensitizer (PS) in the presence of oxygen to form cytotoxic species. Fractionation of light delivery may enhance treatment efficiency by restoring tissue oxygenation.Objectives: To evaluate the efficiency of two light fractionation schemes, using immunohistological data. Materials and Methods: Thirty-nine “Nude” rats were grafted with human U87 cells into the right putamen. After PS precursor intake (5-ALA), an optic fiber was introduced into the tumor. The rats were randomized in three groups: without light, with 2 fractions and 5 fractions. Treatment effects were assessed from brain immunohistology. Results: Histology confirmed more extensive necrosis and apoptosis associated with a rarified angiogenic network in the treatment area, after multifractionated PDT. However, we observed more surrounding edema and neovascularization in the peripheral ring after 5-fractionned PDT.Conclusion: Interstitial PDT with fractionated scheme induced specific tumoral lesions. The 5 fractions scheme was more efficient, inducing greater tumoral necrosis and apoptosis, but also significant peripheral edema and neovascularization.