肿瘤学研究与治疗杂志

抽象的

Determination of the Cutoff Point of the Absolute Value of MGMT mRNA for Predicting the Therapeutic Resistance to Temozolomide in Glioblastoma

Satoshi Tanaka, Jiro Akimoto and Yoshitaka Narita

Abstract Purpose: In our previous study we have reported the absolute value of O6-methylguanine-DNA methyltransferase (MGMT) messenger RNA (mRNA) which was acquired by using real-time reverse transcription polymerase chain reaction (RT-PCR). Probably the value may be useful for envisioning both the prognosis and the outcomes of the therapy for glioblastoma (GB) treated by Temozolomide (TMZ). Methods: MGMT mRNA was studied in 55 newly diagnosed cases of GB treated with TMZ and radiation (with less than 75 y and had a Karnofsky performance status (KPS) of at least 60), based upon the technique of realtime reverse transcription polymerase chain reaction (RT-PCR) using the TaqMan probe. A receiver operating characteristic analysis was carried out in order to determine the cutoff points for progression free survival (PFS) as well as overall survival (OS). Results: In 55 patients with GB, 1200 and 3600 for PFS (specificities of 88.9 and 66.7%, and sensitivities of 36.7 and 50.0%, respectively); 1200, 2100 and 2900 copies/μg RNA for OS (specificities of 83.6, 73.9 and 69.6%, and sensitivities of 39.1, 47.8 and 52.2%, respectively) were the candidate cutoff points. Significantly longer PFS and OS were observed in patients who did not exceed 1200 copies/μg RNA (p=0.0035 for PFS and 0.0189 for OS by logrank test). Median overall survival of the GB patients who had less than 1200 copies/μg RNA treated with TMZ and radiation was 36 months. Conclusion: One Thousand and two hundreds copies/μg RNA appeared to be the most reasonable cutoff point of MGMT mRNA in GB for deciding to use other anti-tumor drugs such as Bevacizumab together with TMZ.