P17.63 * COMBINATION THERAPY WITH TEMOZOLOMIDE, INTERFERON-BETA, AND RIBAVIRIN IN GLIOMA CELL LINES

Abstract

INTRODUCTION: Although Temozolomide (TMZ) with radiotherapy significantly improves the survival of newly diagnosed glioblastoma although most patients develop tumor progression within 1-2 years. The Japan Clinical Oncology Group (JCOG) are ongoing a phase II randomized study to evaluate the clinical effectiveness of TMZ and Interferon-β (IFN-β) combination therapy in glioblastoma patients. Meanwhile, Ribavirin (RBV) is a standard agent of treating of chronic hepatitis C together with interferon-α. Recently, an anti-tumor effect of RBV was reported in breast cancer and chronic myelocytic leukemia. We evaluated the effect of TMZ, IFN-β, and RBV combination therapy in glioma cell lines. METHODS: Glioma cell lines used were A-172, AM-38, T98G, U-87MG, U-138MG, U-251MG, and YH-13. Glioma cell lines were cultured in an incubator for 48 hours and administered with either 1. TMZ (10 µM) + IFN-β (10 IU/ml) or 2. TMZ (10 µM) + IFN-β (10 IU/ml) + RBV (10 µM). At 72 to 96 hours post-treatment, the number of remaining glioma cells were counted to evaluate the growth-inhibitory effects of each therapy. In addition, cell cycle changes by flow cytemetry and p53 activity with western blot analysis were examined from U-87 MG cell line. RESULTS AND CONCLUSIONS: In all cell lines, the triple combination therapy enhanced the growth-inhibitory effect compared to dual combination therapy. Triple therapy led to distribution of G2/M phase of the cell cycle and accumulated p53 activety. Rivabirin enhanced antitumor effect of TMZ and IFN combination therapy in glioma cell lines.