MGMT promoter methylation as a predictive biomarker for response to radiotherapy versus chemotherapy in malignant astrocytomas in the elderly: The NOA-08 trial.

Abstract

2000 Background: In a few years more than half of the patients with glioblastoma will be older than 65 years of age and thus be classified as elderly. The current standard of care in elderly patients with glioblastoma (GB) or anapestic astrocytoma (AA) is resection or biopsy followed by involved-field radiotherapy (RT). The role of primary chemotherapy is poorly defined. The NOA-08 trial compared efficacy and safety of RT to temozolomide (TMZ) in patients with newly diagnosed AA or GB. Methods: Patients (N=412; 39 AA, 373 GB) > 65 years with a Karnofsky performance score > 60 were randomized to receive RT or TMZ. The primary endpoint was overall survival (OS). The trial sought to demonstrate the non-inferiority of TMZ compared with RT. Results: Patient characteristics in the intention-to-treat population [N=373 (178 patients RT, 195 patients TMZ)] were balanced. All histologic diagnoses (11% AA and 89% GB) were centrally confirmed. Median OS [HR=1.09 (95% CI: 0.84-1.42)] and event-free survival (EFS) [hazard ratio (HR)=1.15 (0.92-1.43)] of TMZ versus RT did not differ between both arms. Non-inferiority of TMZ compared with RT was significant (p<0.05). Extent of resection, but not age or diagnosis of AA were associated with prolonged EFS and OS. DNA repair protein O6-methylguanine DNA-methyltransferase (MGMT) promoter methylation in tumor tissue was associated with prolonged OS [HR=0.67 (0.38-1.29)]. Patients with MGMT promoter methylation had longer EFS when treated with TMZ (8.4 months [5.5-11.7] versus RT (4.6 [4.2-5] months) whereas patients without MGMT promoter methylation had longer EFS when treated with RT (4.6 [3.7-6.3] versus 3.3 [3-3.5] months). This effect persisted for OS. Conclusions: NOA-08 demonstrates the non-inferiority of TMZ compared with RT in the treatment of elderly patients with malignant astrocytoma. MGMT promoter methylation is a strong predictive biomarker for the choice between RT and TMZ.