Temozolomide Plus Radiotherapy Yields Survival Benefit in IDH-Mutant LGG
A recent study has revealed a significant survival advantage for patients with IDH-mutant low-grade gliomas (LGG) when temozolomide is combined with radiotherapy. This combination therapy outperformed radiotherapy alone, particularly in patients without codeletions of 1q and 19q.
The ECOG-ACRIN E3F05 trial, a phase 3 study, analyzed the impact of adding temozolomide to radiotherapy in patients with IDH-mutant, symptomatic or progressive LGG. The results, presented at the 2025 Society for Neuro-Oncology (SNO) Annual Meeting, showed a statistically significant improvement in overall survival (OS) and progression-free survival (PFS) for these patients.
Key Findings:
- Patients with IDH-mutated disease without codeletions experienced a 15% reduction in the risk of death when temozolomide was added to radiotherapy (HR: 0.15; 95% CI: 0.03-0.74).
- Patients with codeletions also benefited, with a 51% reduction in the risk of death (HR: 0.51; 95% CI: 0.19-1.42).
- Numerical PFS benefits were observed in both groups, indicating improved disease control.
The study's lead author, David Schiff, MD, emphasized the importance of these findings, noting that the sample sizes were too small to declare statistical significance for patients with codeletions.
Trial Design and Evolution:
The ECOG-ACRIN E3F05 trial initially enrolled patients with grade II glioma who had not received prior radiotherapy or chemotherapy. Patients were randomly assigned to receive either radiotherapy alone or radiotherapy with concomitant temozolomide, followed by 12 cycles of temozolomide. The trial's design evolved due to changes in glioma classification systems.
Initially, the trial was activated before the advent of IDH testing, but later, updated findings from the RTOG 9802 trial suggested a benefit from adding chemotherapy, making the control arm unethical. As a result, the trial was halted with 172 enrolled patients, and methylation profiling was used to determine IDH mutational status.
Efficacy Data and Updates:
Previous reports from SNO 2024 highlighted a 54% reduction in the risk of death with the addition of temozolomide to radiotherapy (HR: 0.54; 95% CI: 0.31-0.95). The latest updates from SNO 2025 revealed even more promising results:
- 5-year PFS rates: 76% with temozolomide vs. 53% with radiotherapy alone.
- 10-year PFS rates: 59% with temozolomide.
- 5-year OS rates: 94% with temozolomide plus radiotherapy vs. 71% with radiotherapy alone.
- 10-year OS rates: 80% with temozolomide plus radiotherapy vs. 39% with radiotherapy alone.
Schiff emphasized the significant benefit of adding temozolomide in IDH-mutant astrocytomas, particularly for long-term survival.
In summary, the study demonstrates a clear survival advantage for patients with IDH-mutant LGG when temozolomide is combined with radiotherapy, especially in those without codeletions. These findings highlight the importance of personalized treatment approaches in neuro-oncology.
