On October 18, 2025 EORTC reported that final results from CATNON trial show that the addition of 12 cycles of chemotherapy to radiotherapy can improve overall survival in a group of patients with a particular type of the rare brain tumour anaplastic glioma. The data will be presented today [Saturday] at the 20th Meeting of the European Association of Neuro-Oncology (EANO) by the study’s principal investigator, Dr Martin van den Bent, from the Erasmus MC Cancer Centre, Rotterdam, The Netherlands.

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The results show that, after a median follow up of nearly 11 years, the addition of 12 cycles of the chemotherapy agent temozolomide (TMZ) to radiotherapy in patients with an anaplastic astrocytoma improved overall survival in the subset of patients with a tumour that had a mutation in the IDH gene (IDHmt). The median overall survival in IDHmt patients who received TMZ after RT was around 12 years.

There was no observable benefit when TMZ chemotherapy was given during radiotherapy, nor in patients in which the tumour did not show an IDH mutation. Several biological markers were associated with outcome in patients with an IDH mutated glioma but, importantly, benefit from the treatment was still observed regardless of those markers.

The study was carried out by researchers from ten countries worldwide, and randomised 751 adult patients with newly diagnosed anaplastic glioma to radiotherapy alone, radiotherapy with concurrent TMZ, radiotherapy with TMZ given after treatment (adjuvant therapy), and radiotherapy with both concurrent and adjuvant TMZ. The patients were enrolled in the trial between 2007 and 2015.

The researchers found that adjuvant (post-radiation) TMZ significantly extended survival. The study confirms the importance of distinguishing between patients with tumours with an IDH mutation and those without. In patients whose tumours had the IDH mutation, the median survival increased to 12.5 years compared with six years in the control group who were initially treated with radiotherapy only. There was no benefit to patients who had concurrent TMZ if they also received an adjuvant treatment, regardless of the IDH status of the tumour.

Methylation profiling, a technique that allows the precise detection of specific regions of DNA, helped predict patient prognosis but did not affect their response to TMZ. This suggests that the chemotherapy benefits most risk groups, the researchers say. The use of methylation profiling to identify DNA modifications showed that more aggressive tumours had significantly worse outcomes, but all patients with IDH-mutant tumours benefited from the standard treatment.

This combined treatment should become the standard of care for patients with anaplastic astrocytoma with an IDH mutation, according to the researchers. This was underlined by the EANO Scientific Committee with its award of the Best Oral Presentation for Clinical Research. Dr van den Bent said: "These results emphasise the importance of long-term follow-up. Thanks to the commitment of patients and the collaboration with partners worldwide, we have been able to identify the optimal treatment strategy that can extend life significantly in this patient population."

EORTC CEO Dr Denis Lacombe said: "Given the rarity of these tumours and the fact that the role of IDH in glioma was only discovered recently, it is a significant achievement to have delivered these results in a short time period, and further underlines the important role of academic clinical research in helping rare disease patients."

Presentation number: OS05.2.A Final clinical and molecular analysis of the EORTC randomized phase III intergroup CATNON trial on concurrent and adjuvant temozolomide in anaplastic glioma without 1p/19q codeletion.

(Press release, EORTC, OCT 18, 2025, View Source [SID1234656764])