Sequencing 183 IDH-mutant gliomas finds oligodendrogliomas and astrocytomas recur by different genetic routes
A Nature study of 183 IDH-mutant gliomas found PI3K and NOTCH1 mutations newly acquired in recurrent oligodendrogliomas. The authors suggest the two tumour types respond differently to treatment-induced DNA damage.
The Scientist · Science desk
Key figures: 93% of oligodendroglioma primary surgery samples and 73% of astrocytoma primary surgery samples were classified as grade 2 by histology. The study covered 183 patients with IDH-mutant glioma.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Oligodendroglioma primary samples graded 2 by histology | 93% | 3 | |
| Astrocytoma primary samples, grade 2 | 73% | primary surgery samples, by histology | 3 |
| IDH-mutant glioma patients | 183 patients | 1 |
What happened
- The PI3K and NOTCH1 mutations arose regardless of treatment and were associated with higher tumour mutational burden.
- Recurrent astrocytomas instead gained focal oncogene amplifications and CDKN2A/B deletions, linked to more chromosomal imbalance, chromothripsis and whole-genome doubling.
- Temozolomide was associated with signatures SBS11 and SBS119 in both types, while the radiotherapy-linked ID8 signature rose in astrocytomas only.
Why it matters
- decision Analyses that pool both types would average away a radiotherapy signature seen in astrocytomas only, so tumour type becomes the variable to split on.
- constraint Every reported link is an association in observed patients, so the data suggest clone selection without showing that any single mutation drives resistance.
- cost Patients are usually diagnosed young to middle-aged, so resistance in virtually all of these tumours costs a disproportionate number of life years, the authors write.
Sampling each patient over time is what lets the authors call a mutation newly acquired. The team sequenced longitudinally collected specimens from 183 patients [1], drawn through the GLASS Consortium [2]. A comparison of primary tumours in one group of people with recurrences in another could not separate acquired change from differences between patients.
The cohort reproduces what earlier work found. It validated hypermutation and homozygous deletion of CDKN2A/B as markers of progression [4]. Prior longitudinal profiling had already shown that a subset of IDH-mutant gliomas treated with alkylating agents acquires a hypermutant genotype [13], and had tied gains of MYC and PDGFRA to shorter survival after recurrence [15].
The two tumour types are defined differently. Under the 2021 WHO classification, oligodendrogliomas show combined loss of chromosome arms 1p and 19q, and astrocytomas lack that codeletion [14]. The paper's introduction says it was unknown whether treatment-associated molecular responses specific to each type exist [12].
The abstract describes two layers. The type-specific acquisitions were reported irrespective of treatment [6][7]; the mutational signatures are the changes tied to a particular therapy [9]. In both types, acquired alterations, genome-wide changes and worse patient outcomes converged, and the authors say this suggests treatment-refractory clones were being selected [8].
The thing this doesn't tell you is whether any of it causes resistance. Each link reported is an association: PI3K and NOTCH1 mutations with higher mutational burden [5][6], astrocytoma amplifications and deletions with chromosomal imbalance [7], converged changes with worse outcomes [8]. The abstract does not say which came first in the mutation-and-burden pairing, and it does not report how the 183 patients split between the two types or how long they were followed.
The grade mix also bounds who the results describe. Most first-surgery samples were grade 2 by histology [3], which leaves 27% of astrocytoma and 7% of oligodendroglioma primary samples that were not classified grade 2 [16].
In our view the split between types is well supported in this cohort, since it held irrespective of treatment and the pipeline recovered known markers. Selection of resistant clones is a hypothesis the authors word as a suggestion, and sequencing of patient tumours cannot test it alone.
What to watch
- Whether an independent cohort of recurrent oligodendrogliomas reproduces the PI3K and NOTCH1 acquisitions, with sample counts reported by tumour type.
- Tumour-model experiments that test whether PI3K or NOTCH1 mutation changes how oligodendroglioma cells respond to treatment.
- Whether IDH-mutant glioma trials begin reporting astrocytoma and oligodendroglioma outcomes separately.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence72
- Adoption
- Insufficient
- Hype gap−5
- Incentives
- Insufficient
- Confidence60
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Whole-genome and whole-exome sequencing was used to characterise longitudinally collected tumour specimens from 183 patients with IDH-mutant glioma.
- [2]
The samples were collected through the Glioma Longitudinal Analysis (GLASS) Consortium.
- [3]
Most primary surgery samples were classified as grade 2 on the basis of histology: 73% for astrocytomas and 93% for oligodendrogliomas.
- [4]
The study validated known genomic markers of tumour progression, including hypermutation and homozygous deletion of CDKN2A or CDKN2B.
- [5]
Mutations in PI3K and NOTCH1 were newly acquired in recurrent oligodendrogliomas.
- [6]
The PI3K and NOTCH1 mutations in recurrent oligodendrogliomas were acquired regardless of treatment and were associated with an increased tumour mutational burden.
- [7]
In recurrent astrocytomas, irrespective of treatment, acquired focal oncogene amplifications and CDKN2A/B homozygous deletions were associated with an increase in chromosomal imbalances, which converged with markers of chromosomal instability such as chromothripsis and whole-genome doubling.
- [8]
In both types of IDH-mutant glioma, acquired alterations, genome-wide changes and worse patient outcomes converged, which the authors say suggests that treatment-refractory clones were being selected.
- [9]
Temozolomide treatment was associated with the mutational signatures SBS11 and SBS119 in both tumour types, whereas the radiotherapy-associated ID8 signature increased in astrocytomas specifically.
- [10]
The authors conclude that the genomes of oligodendrogliomas and astrocytomas adapt to tumour progression and treatment in distinct ways, suggesting the two types differ in their responses to treatment-induced DNA damage.
- [11]
IDH-mutant gliomas are usually diagnosed in young to middle-aged individuals, so the ubiquitous emergence of treatment resistance results in a disproportionate number of life years lost.
- [12]
The paper's introduction says it is unknown whether treatment-associated molecular responses exist that are specific to the individual IDH-mutant glioma types.
- [13]
Earlier longitudinal profiling showed that a subset of IDH-mutant gliomas treated with alkylating agents acquires a hypermutant genotype.
- [14]
Under the 2021 WHO classification, IDH-mutant oligodendrogliomas (grades 2-3) are characterized by combined loss of chromosome arms 1p and 19q, and IDH-mutant astrocytomas (grades 2-4) lack the 1p/19q codeletion.
- [15]
Earlier profiling showed that gains of oncogenes such as MYC and PDGFRA are associated with shorter post-recurrence survival.
- [16]
27% of astrocytoma and 7% of oligodendroglioma primary samples were not classified as grade 2 by histology.
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Sources
1 independent publisher whose own reporting we read for this story.
- nature.comDivergent genomic evolution in astrocytomas and oligodendrogliomas
1 article · October 13, 2026
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