RTID-09. A RANDOMIZED, DOUBLE-BLINDED, PHASE 3 STUDY OF ENZASTAURIN ADDED TO TEMOZOLOMIDE DURING AND FOLLOWING RADIATION THERAPY IN NEWLY DIAGNOSED GLIOBLASTOMA PATIENTS WHO POSSESS THE NOVEL BIOMARKER, DGM1

Abstract

Abstract BACKGROUND Limited progress has been made in improving therapeutic outcomes for glioblastoma (GBM) patients. Enzastaurin (enza) is an oral PKC-β inhibitor that suppresses signaling through the PKC and PI3K/AKT pathways. Although enza did not significantly improve survival in a prior Phase 1/2 study, we have identified a novel genomic biomarker, DGM1, that may predict a response to enza in GBM. PRIMARY OBJECTIVE To assess whether enza added to temozolomide and radiation therapy (RT) improves overall survival (OS) in newly diagnosed GBM patients who possess the DGM1 biomarker. POPULATION Adults with newly diagnosed GBM regardless of DGM1 status who have undergone surgical resection and are candidates for chemoradiation. Approximately 318 patients will be enrolled. DGM1 status will be determined prior to analysis. DESIGN This is a randomized, double-blinded, placebo-controlled study. Patients will be stratified by MGMT and IDH1 status and by geographic region. Treatment will be divided into 3 phases. In the Concurrent Phase (6 weeks), patients will receive RT plus temozolomide and either enzastaurin or placebo. Patients will then enter the Single-Agent Phase and receive either enza or placebo (21-35 days). Then, patients will enter the Adjuvant Phase and receive temozolomide with either enza or placebo (6-12 cycles) followed by enza or placebo alone (to 24 cycles total). ANALYSIS The primary efficacy endpoint of OS will be analyzed using stratified log-rank test for all DGM1-positive randomized patients. The study has approximately 90% power to detect a HR of 0.63 assuming 196 OS events based on a 2.5% one-sided false positive error rate. Statistical significance would be achieved with an estimated observed HR < 0.76. Safety evaluation will include all patients receiving at least one dose of enza or placebo. If OS in DGM1-positive patients is statistically significant, OS in the overall population will be assessed.