RB1 and central nervous system cancer: Concurrent alterations in NTRK fusion gliomas demonstrate increased frequency with older age.6 In a cohort of 22 adults patient with NTRK fusion glioma, the most frequently detected concurrent genomic changes included CDKN2A/B deep deletion, TERT promoter mutation, PTEN loss or mutation, TP53 mutation, IDH1 mutation, polysomy 7, and RB1 loss or mutation, with most observed at frequencies consistent with that seen in GBM.