IDH1 and central nervous system cancer: Inclusion criteria were: patients with residual or recurrent IDH-mutant glioma, at least 12 years old, Karnofsky Performance Scale (KPS) of at least 80, were between 1–5 years out from surgery, were deemed to be a candidate for a watch-and-wait approach, and had measurable non-enhancing (any enhancement had to be nonmeasurable) disease.