A randomized phase II trial of concurrent temozolomide (TMZ) and radiotherapy (RT) followed by dose dense compared to metronomic TMZ and maintenance cis-retinoic acid for patients with newly diagnosed glioblastoma multiforme (GBM)

Abstract

2031 Background: Metronomic and dose dense scheduling are alternatives to conventional TMZ regimens to overcome drug resistance in part by depleting O-6 methylguanine-DNA methyltransferase (MGMT). Furthermore, metronomic TMZ may inhibit endothelial recovery and act as an anti-angiogenic therapy; dose dense TMZ increases the intensity of drug delivery. Objective: To determine the overall (OS) and progression free survival (PFS) of patients with newly diagnosed GBM treated with concurrent TMZ and RT followed by dose dense or metronomic TMZ and maintenance cis-retinoic acid. Methods: Patients with newly diagnosed, histologically confirmed GBM underwent standard RT with TMZ. Upon completion of this treatment, patients were randomized to receive dose-dense TMZ (150mg/m2, days 1–7 and 15–21 of a 28 day cycle) or metronomic TMZ (50mg/m2 daily in 28 day cycles), for 6 cycles. Maintenance cis-retinoic acid was prescribed following the 6 cycles of adjuvant TMZ. OS and PFS were calculated from date of diagnosis. Prospective correlative tissue analysis of MGMT status is planned. A Simon minimax 2-stage design was used for each cohort. If either group has 70% survival probability at 1 year, further evaluation in a phase III trial will be recommended. Results: 51 patients were randomized: 24 to metronomic, and 27 to dose dense. Median age is 57, and median KPS 90. 26 patients have progression of disease (POD), with a median follow up of 5 months. Grade 3/4 hematologic toxicity occurred in 7 patients (14%), 3 in the metronomic and 4 in the dose dense arm. Conclusions: Our patient population is comparable to that of other upfront GBM treatment trials. Metronomic and dose dense TMZ appear to be well tolerated with equivalent toxicities. Early analysis suggests that patients on the dose dense regimen may have better PFS than those on the metronomic arm. [Table: see text] No significant financial relationships to disclose.