Feasibility of real-time molecular profiling for patients with newly diagnosed glioblastoma without MGMT promoter-hypermethylation – the NCT Neuro Master Match (N 2 M 2 ) pilot study

Abstract

Introduction

O⁶-methylguanine-DNA methyltransferase (MGMT) promoter methylation status is a predictive biomarker in glioblastoma patients. Glioblastoma without hypermethylated MGMT promoter are largely resistant to treatment with temozolomide. These patients are in particular need of new treatment approaches, which are offered by biomarker-driven clinical trials with targeted drugs based on molecular characterization of individual tumors.

Methods

In preparation for an upcoming clinical study, a comprehensive molecular profiling approach was undertaken on tissues from 43 glioblastoma patients harboring an unmethylated MGMT promoter at diagnosis. The diagnostic pipeline covered various levels of molecular characteristics including whole-exome sequencing, low-coverage whole-genome sequencing, RNA sequencing as well as microarray-based gene expression profiling and DNA methylation arrays.

Results

Complex multilayer molecular diagnostics were feasible in this setting with a median turn-around time of 4–5 weeks from surgery to the molecular tumor board. In 35% of cases potentially relevant therapeutic decisions were derived from the data. Alterations were most frequently found in receptor tyrosine kinases, members of the phosphoinositide 3-kinase / Akt / mechanistic target of rapamycin and mitogen-activated protein kinase pathway as well as cell cycle control and p53 regulation cascades. Individual tumors harbored clonal alterations such as oncogenic fusions of tyrosine kinases which constitute promising targets for targeted therapies. A prioritization algorithm is proposed to allocate patients with multiple targets to the potentially best treatment option.

Conclusion

With this feasibility study, a comprehensive molecular profiling approach for patients with newly diagnosed glioblastoma harboring an unmethylated MGMT promoter is presented. Analyses in this pilot cohort serve as a basis for trials based on targetable alterations and on the question of allocation of patients to the best treatment arm.