Protracted Adjuvant Temozolomide in Glioblastoma Multiforme

Abstract

Purpose: Radiotherapy with concurrent temozolomide (TMZ), followed by 6 cycles of adjuvant TMZ, is the standard of care for newly diagnosed Glioblastoma Mulltiforme (GBM). However tumor progression is the role with median survival of almost 14 months. With lack of effective second line chemotherapy, many physicians and some guidelines advocate prolonged use of adjuvant TMZ more than 6 months. We conduct this study to test the efficacy of protracted adjuvant conventional dose TMZ over the standard 6 doses of adjuvant TMZ. Material and Methods: This phase II trial enrolled patients newly diagnosed as GBM, older than age 18 years, with a Karnofsky performance score (KPS) of ≥60, Neurological Performance Scale (NPS) of ≤3. Patients were randomly assigned to the standard concurrent chemoradiotherapy (CCRT) followed by 6 cycles of adjuvant TMZ or the same treatment with more than 6 cycles of adjuvant chemotherapy extended as long as the patient in good performance, with no unacceptable toxicity, no signs of disease progression. The primary end point was OS. Results: A total of 59 patients were recruited in the study and were randomized in two arms. 29 patients joined arm 1 aiming at receiving CCRT followed by adjuvant 6 cycles TMZ (6 cycles arm) and 30 joined arm 2 aiming at receiving the same treatment with more than 6 cycles of TMZ (>6 cycles). 16 patients managed to complete the adjuvant 6 cycles in arm 1. 19 patients in arm 2, completed the 6 cycles with additive more doses with a median of 11 cycles (range: 8 - 23 cycles). Median PFS was 12.1 months for (6 cycles) arm, and 18.8 months for (>6 cycles) arm, HR 0.88 (95% CI: 1.185 - 4.901) (P 0.015); the overall survival for (6 cycles) arm was 18.1 months, versus 24.1 months, HR 0.70 (95% CI: 1.007 - 4.037) (P 0.048). No significant added toxicity was notice and the 4 weekly TMZ was well tolerated. Conclusion: This study concluded that protracted adjuvant TMZ after concurrent chemoradiotherapy could be a feasible strategy for GBM. This strategy warrants a large phase III randomized trial.