Clinical trialPhase 3Brain tumours

Concurrent and adjuvant temozolomide for 1p/19q non-co-deleted anaplastic glioma (CATNON; EORTC study 26053-22054): final and exploratory analyses of a randomised, open-label, phase 3 trial

Lancet Oncol · 2026751 randomised patients (444 with IDH-mutant tumours)

van den Bent MJ, Ghisai SA, Wick W, Sanson M, Brandes AA, Clement PM, et al. Lancet Oncol. 2026. 27:45-56

Study type: Clinical trial
Study name: CATNON (EORTC 26053
Phase: Phase 3
Design: Open-label, four-group randomised trial (1:1:1:1) at 137 centres in Australia, Europe and North America
Sample size: 751 randomised patients (444 with IDH-mutant tumours)
Source: Lancet Oncol · 2026
Trial registration: NCT00626990

In plain words

This final report, after about 11 years of follow-up, showed that in grade 3 astrocytoma with an IDH mutation, taking temozolomide tablets for 12 cycles after radiotherapy had finished raised median survival from about 6 years to about 12.5 years; taking it at the same time as radiotherapy gave no significant benefit.

Key results

HR 0.65

Adjuvant temozolomide in all patients (overall survival)

95% CI 0.54–0.77; median follow-up 10.9 years

HR 0.91

Concurrent temozolomide in all patients (overall survival)

95% CI 0.76–1.08; no significant benefit

12.5 vs 6.0 years

IDH-mutant tumours: median overall survival with and without adjuvant temozolomide

HR 0.54 (0.42–0.69)

9.7 vs 7.2 years

IDH-mutant tumours: median overall survival with and without concurrent temozolomide

HR 0.81 (0.63–1.04); not significant

Drugs in this study:Temozolomide (Temodal)

Dose and schedule cards

Radiotherapy followed by 12 cycles of adjuvant temozolomide (CATNON)

IDH-mutant astrocytoma (anaplastic glioma without 1p/19q codeletion), grade 3, and grade 2 when adjuvant chemotherapy is given; WHO PS 0 to 2Cycle length: Every 28 daysOn the page “Brain tumours” · IDH-mutant gliomas (astrocytoma and oligodendroglioma)

IDH-mutant astrocytoma (anaplastic glioma without 1p/19q codeletion), grade 3, and grade 2 when adjuvant chemotherapy is given; WHO PS 0 to 2

Drug	Dose	Route	Schedule
Radiotherapy
Radiotherapy	59.4 Gy in 33 fractions	External beam radiotherapy	Daily
Adjuvant: starting 4 weeks after the end of radiotherapy
Temozolomide (cycle 1)	150 mg/m² once daily	Oral	Days 1 to 5
Temozolomide (cycles 2 to 12)	200 mg/m² if there was no or minimal toxicity in cycle 1	Oral	Days 1 to 5

Cycle length: Every 28 days
Duration: 12 cycles (about 1 year)

Temozolomide concurrent with radiotherapy (75 mg/m² daily) gave no significant benefit; the benefit came from adjuvant temozolomide. Blood count monitoring, dose reduction and liver tests for temozolomide as in the temozolomide “Common safety considerations” in the glioblastoma regimens. Dose source:.

On the page “Brain tumours” · IDH-mutant gliomas (astrocytoma and oligodendroglioma)

Newly diagnosed anaplastic astrocytoma (adjuvant)

After radiotherapyOn the page “Temozolomide (Temodal)” · Dose and schedule (FDA label and key trials)

After radiotherapy

Drug	Dose	Route	Schedule
Cycle 1
Temozolomide	150 mg/m² a day	Oral	Days 1 to 5
Cycles 2 to 12
Temozolomide	200 mg/m² a day (if there was no or minimal toxicity in cycle 1)	Oral	Days 1 to 5

Cycle length: Every 28 days, starting 4 weeks after the end of radiotherapy
Duration: 12 cycles

As in the FDA label; in the CATNON trial (anaplastic glioma without 1p/19q co-deletion), 12 four-weekly cycles of 150 to 200 mg/m² on days 1 to 5 were also given after radiotherapy of 59.4 Gy in 33 fractions.

On the page “Temozolomide (Temodal)” · Dose and schedule (FDA label and key trials)

Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.

Treatment arms and regimens

1Radiotherapy alone

Focal radiotherapy (3D conformal or IMRT) 59.4 Gy in 33 fractions.

2Radiotherapy + concurrent temozolomide

Radiotherapy 59.4 Gy in 33 fractions with oral temozolomide 75 mg/m² daily throughout radiotherapy.

Monitoring: weekly blood counts during concurrent temozolomide; every 4 weeks during radiotherapy and adjuvant temozolomide, blood counts, liver and kidney tests and electrolytes.

3Radiotherapy + adjuvant temozolomide

Radiotherapy 59.4 Gy in 33 fractions; then, 4 weeks after the end of radiotherapy, 12 cycles of oral temozolomide on days 1 to 5 every 28 days: cycle 1 at 150 mg/m² per day and, if there was no or minimal toxicity, later cycles at 200 mg/m² per day.

Monitoring: weekly blood counts during concurrent temozolomide; every 4 weeks during radiotherapy and adjuvant temozolomide, blood counts, liver and kidney tests and electrolytes.

4Radiotherapy + concurrent and adjuvant temozolomide

Radiotherapy 59.4 Gy in 33 fractions with concurrent temozolomide 75 mg/m² daily, then, 4 weeks after the end of radiotherapy, 12 cycles of temozolomide (days 1 to 5 every 28 days; cycle 1: 150, then 200 mg/m² per day if tolerated).

Monitoring: weekly blood counts during concurrent temozolomide; every 4 weeks during radiotherapy and adjuvant temozolomide, blood counts, liver and kidney tests and electrolytes.

Source of the regimen details: Abstract of the paper (Lancet Oncol 2026) and the "Treatment" section of the full report of the second interim analysis (Lancet Oncol 2021, PMC8191233; timing of adjuvant start, dose escalation and monitoring)

Doses are given for the information of specialists, as in this study’s protocol, and are not a prescription. Every drug must be prescribed by the treating physician for the individual patient.

Study population

Adults aged 18 years or older with newly diagnosed anaplastic glioma without 1p/19q co-deletion and WHO performance status 0 to 2.

Endpoints

Primary endpoint: overall survival adjusted for stratification factors in the intention-to-treat population. Exploratory analysis in patients with IDH-mutant astrocytoma.

Safety and side effects

Safety data are not presented in this final report. In the second interim analysis (2021), the most common grade 3 and 4 toxicities were haematological: none in the radiotherapy-alone group, 16 of 185 (9%) in the concurrent temozolomide group and 55 of 368 (15%) in the two groups receiving adjuvant temozolomide; no treatment-related deaths were reported.

Clinical significance and place in guidelines

This final analysis establishes radiotherapy followed by 12 cycles of adjuvant temozolomide (without concurrent temozolomide) as the treatment for IDH-mutant grade 3 astrocytoma, in line with the ASCO-SNO guideline, which recommends radiotherapy and adjuvant temozolomide for these patients.

Limitations

Open-label design; the analysis in the IDH-mutant subgroup is exploratory and univariable; patients were enrolled before the WHO 2021 classification.

Original article (DOI)PubMed ClinicalTrials.gov

This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.