BIMG-15. LACTATE AND GLUTATHIONE LEVELS DETECTED WITH PROTON MR SPECTROSCOPY ARE ASSOCIATED WITH POOR SURVIVAL IN IDH WILD TYPE TERTP MUTANT DIFFUSE GLIOMAS

Telomerase reverse transcriptase promoter (TERTp) mutations in the absence of IDH mutations (TERTp-only) are recently proposed as a characteristic of glioblastoma regardless of the morphological grade. This study aims to analyze metabolic profiles of TERTp-only gliomas using proton magnetic resonance spectroscopy ((1)H-MRS) and evaluate the effect of metabolite concentrations on progression-free survival (PFS) and overall survival (OS). The patient cohort consisted of 56 TERTp-only gliomas (35M/21F, mean age: 58±10.37 years, 44 glioblastomas (GBM), and 12 lower-grade gliomas with TERTp-mutation but no IDH-mutations). All patients underwent preoperative diagnostic (1)H-MRS using a 3T MR scanner with a 32-channel head coil. (1)H-MRS was obtained from a manually placed region of interest with no necrosis, edema, and hemorrhage, using a Point Resolved Spectroscopy (PRESS) sequence (TR/TE=2000/30 ms, 1024 points). LCModel spectral fitting program was used for quantification of MR spectroscopic peak concentrations of 17 metabolites. The patients were divided into two groups using median values of the metabolite intensities, and Kaplan-Meier survival analysis followed by a log-rank test was used to determine the effects of metabolite concentrations on OS and PFS. Median PFS and OS of TERTp-only gliomas were 11 and 17 months, respectively. TERTp-only LGG patients had longer OS and PFS than TERTp-only GBM patients (p=0.022 for OS and p=0.018 for PFS). Significantly shorter OS and PFS were identified in TERTp-only gliomas, who had higher GSH/tCr (p=0.011 for OS and p=0.004 for PFS) and higher Lac/tCr (p=0.014 for OS and p=0.012 for PFS). Lactate is a marker of necrosis and a sign of malignancy. On the other hand, both tCr and GSH were lower, which resulted in higher GSH/tCr, in TERTp-only GBM. The results of this study indicate that high Lac/tCr and GSH/tCr might be indicators of poor prognosis in TERTp-only gliomas. This study has been supported by TUBITAK 1003 grant 216S432.