Background
Comprehensive genomic sequencing study (not a clinical trial). Combined high-throughput sequencing data from 294 grade II and III gliomas to delineate the complete mutational landscape and define molecular subtypes. Identified key driver mutations, their chronological hierarchy, and three discrete molecular subtypes aligning with clinical behavior — the molecular framework underlying modern WHO 2021 glioma classification.
Interventions and follow up
Methods: Whole-exome sequencing, transcriptome sequencing, and copy-number analysis of grade II and III gliomas (N=294); assessment of IDH1/2, TERT promoter, 1p/19q codeletion, ATRX, and TP53; clonal architecture inferred from variant allele frequencies
Primary objective: Define the mutational landscape and molecular subtypes of grade II/III glioma
mFollow up: NR — genomic study, no survival follow-up
Primary objective: Define the mutational landscape and molecular subtypes of grade II/III glioma
mFollow up: NR — genomic study, no survival follow-up
Results
Subtype 1 (oligodendroglioma lineage): IDH mutant + 1p/19q codeleted + TERT mutation; best prognosis
Subtype 2 (astrocytoma lineage): IDH mutant + ATRX loss/TP53 mutation (non-codeleted); intermediate prognosis
Subtype 3 (GBM-like): IDH wild-type, may have TERT or EGFR amplification; poor prognosis
Mutation hierarchy: IDH mutation is the early truncal founding event; TERT promoter mutations occur early in oligodendroglioma lineage and late/independently in IDH wild-type GBM
Lineage exclusivity: 1p/19q codeletion mutually exclusive with ATRX loss; CIC, FUBP1, NOTCH1 co-occur with codeletion
Subtype 2 (astrocytoma lineage): IDH mutant + ATRX loss/TP53 mutation (non-codeleted); intermediate prognosis
Subtype 3 (GBM-like): IDH wild-type, may have TERT or EGFR amplification; poor prognosis
Mutation hierarchy: IDH mutation is the early truncal founding event; TERT promoter mutations occur early in oligodendroglioma lineage and late/independently in IDH wild-type GBM
Lineage exclusivity: 1p/19q codeletion mutually exclusive with ATRX loss; CIC, FUBP1, NOTCH1 co-occur with codeletion
Adverse events
Toxicity endpoints: None — genomic study, no treatment administered
Survival/treatment endpoints: NR
Survival/treatment endpoints: NR
Conclusions
Grade II and III gliomas comprise three distinct molecular subtypes defined by IDH status, 1p/19q codeletion, ATRX mutation, and TERT promoter mutation, with discrete biological behaviors and outcomes. The hierarchical mutation order (IDH first → lineage-specific co-mutations) defines therapeutic vulnerabilities and prognostic stratification.
Key Limitations
Not a clinical trial — no survival or treatment endpoints. Molecular subtypes preceded and informed, rather than were validated in, prospective randomized trials. Older histologic classification used; some cases would be reclassified under WHO 2021. Functional validation of all identified driver mutations was not completed.
Clinical Context
One of the foundational genomic studies (with TCGA lower-grade glioma analysis and Ceccarelli Cell 2016) that shaped WHO 2016/2021 glioma classification. In practice: IDH mutation + 1p/19q codeletion = oligodendroglioma; IDH mutation + ATRX loss/TP53 = astrocytoma; TERT promoter mutation in IDH wild-type grade 2/3 glioma is a diagnostic criterion for molecular GBM.