Concurrent and Adjuvant Temozolomide for Newly Diagnosed Grade III Gliomas Without 1p/19q Co-deletion: A Randomized, Open-Label, Phase 2 Study (KNOG-1101 Study)

Purpose: We investigated the efficacy of temozolomide during and after radiotherapy in Korean adults with anaplastic gliomas without 1p/19q co-deletion.

Materials And Methods: This was a randomized, open-label, phase 2 study and notably the first multicenter trial for Korean grade III glioma patients. Eligible patients were aged 18 years or older and had newly diagnosed non-co-deleted anaplastic glioma with an Eastern Cooperative Oncology Group performance status of 0-2. Patients were randomized 1:1 to receive radiotherapy alone (60 Gy in 30 fractions of 2 Gy) (control group, n=44) or to receive radiotherapy with concurrent temozolomide (75 mg/m2/day) followed by adjuvant temozolomide (150-200 mg/m2/day for 5 days during six 28-day cycles) (treatment group, n=40). The primary end-point was 2-year progression-free survival (PFS). Seventy patients (83.3%) were available for the analysis of the isocitrate dehydrogenase 1 gene (IDH1) mutation status.

Results: The two-year PFS was 42.2% in the treatment group and 37.2% in the control group. Overall survival (OS) did not reach to significant difference between the groups. In multivariable analysis, age was a significant risk factor for PFS (hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.04 to 4.16). The IDH1 mutation was the only significant prognostic factor for PFS (HR, 0.28; 95% CI, 0.13 to 0.59) and OS (HR, 0.19; 95% CI, 0.07 to 0.50). Adverse events over grade 3 were seen in 16 patients (40.0%) in the treatment group and were reversible.

Conclusion: Concurrent and adjuvant temozolomide in Korean adults with newly diagnosed non-co- deleted anaplastic gliomas showed improved 2-year PFS. The survival benefit of this regimen needs further analysis with long-term follow-up at least more than 10 years.