Prolonged Temozolomide Maintenance Therapy in Newly Diagnosed Glioblastoma

Background. The impact of prolonging temozolomide (TMZ) maintenance beyond six cycles in newly diagnosed glioblastoma (GBM) remains a topic of discussion. We investigated the effects of prolonged TMZ maintenance on progression-free survival (PFS) and overall survival (OS). Patients and Methods. In this retrospective single-center cohort study, we included patients with GBM who were treated with radiation therapy with concomitant and adjuvant TMZ. For analysis, patients were considered who either completed six TMZ maintenancecycles group B), continued with TMZ therapy beyond six cycles group C), or stopped TMZ maintenance therapy within the first six cycles group A). Patients with progression during the first six TMZ maintenance cycles were excluded. Results. Clinical data from 107 patients were included for Kaplan-Meier analyses and 102 for Cox regressions. Median PFS times were 8.1 months 95% confidence interval [CI] 6.1-12.4) in group A, 13.7 months 95% CI 10.6-17.5) in group B, and 20.9 months 95% CI 15.2-43.5) in group C. At first progression, response rates of TMZ/lomustine rechallenge were 47% in group B and 13% in group C. Median OS times were 12.7 months 95% CI 10.3-16.8) in group A, 25.2 months 95% CI 17.7-55.5) in group B, and 28.6 months 95% CI 24.4-open) in group C. Nevertheless, multivariate Cox regression for patients in group C compared with group B that accounted for imbalances of other risk factors showed no different relative risk RR) for OS RR 0.77, p =.46). Conclusion. Our data do not support a general extension of TMZ maintenance therapy beyond six cycles.