Impact of IDH1 mutation status on outcome in clinical trials for recurrent glioblastoma

Jacob J. Mandel, MD

The current issue of the Journal of Neuro-Oncology features an paper by neuro-oncologist Jacob J. Mandel and colleagues entitled Impact of IDH1 mutation status on outcome in clinical trials for recurrent glioblastoma. The paper looks at whether patients with IDH-mutated glioblastoma have a higher 6-month progression-free survival (PFS6) or radiographic response (RR) on clinical trials for recurrence. With respect to PFS6, 24 patients were identified who had PFS6 and IDH results. Of those 24 patients, 5 had IDH-mutant GBM. A group of 24 controls without PFS6 also had 5 patients with IDH-mutant GBM. A similar result was obtained with regard to RR. Although median overall survival was 10 months better for the IDH-mutant group, the study determined that IDH mutation status was not predictive of PFS6 or RR in recurrent GBM for this data set. The authors conclude that their results "would seem to indicate that stratifying future recurrent GBM trials based on IDH1 mutation status or excluding pts with IDH1 mutated tumors may be unnecessary if including pts at various recurrences. However, our findings suggest that stratification of pts based on IDH mutation status may potentially be necessary for recurrent GBM clinical trials that limit patient enrollment to first recurrence."