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: NCT00626990.

Background: The 1st and 2^nd interim analyses of the CATNON trial on anaplastic glioma (NCT00626990) showed benefit from adjuvant (adj) temozolomide (TMZ) on overall survival (OS) in patients with IDH mutant (mt) tumors, but no benefit of concurrent (conc) TMZ regardless of Isocitrate dehydrogenase 1 and 2 (IDH) mutation (mt) status. We now present the final analysis and the exploratory molecular marker analysis of the study. Methods: The 2x2 factorial design phase III CATNON trial randomized 751 adult patients with newly diagnosed non-codeleted anaplastic glioma to either 59.4 Gy radiotherapy (RT) alone; the same RT with concTMZ; the same RT and 12 cycles of adjTMZ or the same RT with both concTMZ and adjTMZ. Methylation status including MGMT promoter methylation status were assessed with the Infinium MethylationEPIC Beadchip. IDH mutation (mt) status and glioma specific alterations were assessed with a glioma targeted panel using Agilent SureSelect baits. Results: After a median follow-up of 10.9 years and with 499 events observed, in the intent-to-treat population the hazard ratio (HR) for OS adjusted for stratification factors after concTMZ was 0.906 (95%CI 0.760, 1.082; p=0.28) and after adjTMZ 0.647 (95%CI 0.541, 0.773; p <0.0001). In 660 patients IDH status could be determined: IDH was mt in 444 tumors and wild type (wt) in 216 tumors. Median OS was 1.7 yrs in patients with IDHwt tumors and 8.5 years in patients with IDHmt tumors. Benefit to TMZ was limited to patients with anaplastic glioma IDHmt of which 199 were still alive (45%). For patients with IDHmt tumors the HR for concTMZ was 0.81 (95% CI 0.63-1.04; p=0.09) and for adjTMZ 0.54 (95% CI 0.42-0.69,p < 0.0001). No benefit was observed of concTMZ in IDHmt glioma patients that also received adjTMZ (HR 0.92 95% CI 0.63-1.36; p=0.69). In patients with IDHmt tumors that had received any TMZ median OS was 10.3 years, the median OS in patients treated with adjTMZ was 12.5 years (95% CI 9.4-15.0; p<0.0001). In exploratory analysis, high-copy number Amplification of PDGFR and CDK4; Homozygous deletion of the CDKN2A/B locus, total copy number alterations, methylation subtype (A_IDH vs A_IDH_HG, G-CIMP high versus low, MGMT-promoter methylation as determined by methylation arrays) were all associated with outcome but none was predictive for benefit to TMZ. Conclusions: Despite more follow-up, concTMZ did not improve OS regardless of IDH status. AdjTMZ increased OS in patients with IDHmt tumors but not in patients with IDHwt tumors. Molecular factors of known prognostic significance for IDHmt 1p/19q intact anaplastic glioma did not predict benefit to TMZ. Median OS in patients with IDHmt glioma having received adjTMZ after RT was 12.5 years. Standard of post-operative care in patients with high grade IDHmt astrocytoma should be RT followed by 12 cycles adjTMZ.