IDH1 and astrocytoma (excluding glioblastoma): Analysis of trial results alongside the classification criteria presented here (CDKN2A/B loss and focal amplifications) might further stratify which patients better respond to treatment and whether more aggressive IDH1/2-mutant astrocytomas could benefit from IDH inhibitors.31 In our analysis, 9 of the 250 grade 2 IDH1/2-mutant astrocytoma patients had hemizygous loss of CDKN2A/B and 13 of the 250 had an amplification in CCND2.