Diffuse intrinsic pontine gliomas: New waves

Abstract

Brainstem lesions are heterogenous. Although the majority are astrocytomas, adult and pediatric gliomas differ in their molecular genetic aberrations; gliomas located in the brainstem differ biologically from those located supratentorially; and there is tremendous intratumoral variation in histologic type and genetic profile, as shown in the paper by Warren et al (1) in this issue of Neuro-Oncology. We must perform biopsies to determine the precise histologic types and genetic profiles of lesions in the brainstem. However, textbooks usually state that biopsy or surgery is not required for the diagnosis or treatment of diffuse intrinsic pontine gliomas (DIPGs) and cannot be recommended routinely; diagnosis can be made using MRI alone. The advent of stereotactic biopsy has made the surgical diagnosis of brainstem lesions less dangerous and more feasible. In this issue of the journal, Dellaretti et al (2) report on 96 brainstem biopsies performed at the Roger Salengro Hospital in Lille, France, between February 1988 and August 2007. The overall morbidity rate associated with biopsy was 9%, and one patient died of causes associated with the procedure; these morbidity and mortality rates are considered acceptable. Stereotactic biopsy makes it possible to conduct new clinical studies of DIPG, such as a currently ongoing phase II trial to determine survival after molecularly determined treatment in children and young adults with newly diagnosed DIPG (http://clinicaltrials.gov/ ct2/show/NCT01182350). MRI-guided stereotactic biopsies will be performed. On the basis of molecular parameters after biopsy, patients will receive erlotinib or temozolomide after radiotherapy with bevacizumab. Stratification will be based on O 6 -methylguanine-DNA methyltransferase promoter methylation status and epidermal growth factor receptor expression in tumor biopsy samples. These new treatments for DIPG are now raising hopes for responses to tailored treatment.