cIMPACT-NOW update 3: recommended diagnostic criteria for “Diffuse astrocytic glioma, IDH-wildtype, with molecular features of glioblastoma, WHO grade IV”

Working Committee 1 concluded that histologic grade II and III IDH-wildtype diffuse astrocytic gliomas that contain high-level EGFR amplification, the combination of whole chromosome 7 gain and whole chromosome 10 loss (+7/−10), or TERT promoter mutations, correspond to WHO grade IV and should be referred to as diffuse astrocytic glioma, IDH-wildtype, with molecular features of glioblastoma, WHO grade IV. Assessment of classification by DNA methylation profiling and additional +7/−10 signatures appear to be promising as well and could be considered in the future following additional experience and validation. We also concluded that specific molecular signatures in subsets of IDH-wildtype diffuse astrocytic gliomas are associated with better clinical outcomes and should not lead to a high-grade designation, including, but not limited to, those gliomas with MYB/MYBL or BRAF alterations as individual drivers.