MRS of Glioma Genomics

In France, about 5000 new people with a primary malignant brain tumor are diagnosed each year. The most common primary tumors are gliomas, originating from glial cells (astrocytomas and oligodendrogliomas). Low-grade gliomas are mildly aggressive, but they often evolve into a more malignant form.

Mutations in the genes encoding isocitrate dehydrogenase (IDH) are found in about 80% of low-grade gliomas and are associated with a favorable prognosis. Remarkably, IDH-mutated gliomas are characterized by a specific cellular metabolism causing the accumulation of D-2-hydroxyglutarate (2HG) in tumor cells. 2HG can be detected in vivo using 1H magnetic resonance spectroscopy (MRS) and is recognized as a unique, noninvasive biomarker of IDH-mutated gliomas. Noninvasive detection of IDH mutations via 2HG MRS represents a crucial step for decision-making and patient care.

A subset of IDH-mutated tumors also presents a complete deletion of 1p and 19q chromosome arms (1p/19q codeletion). The 1p/19q codeletion is specifically linked to the oligodendroglial histologic subtype and it has been associated with a better patient outcome. However, the biological effects of this genetic alteration are still unclear and in vivo markers are lacking. Recently, we reported the first in vivo detection of the cystathionine molecule in human brain gliomas using MRS and explored the association between cystathionine accumulation and 1p/19q codeletion in gliomas.

In this project, the investigation team will combine cutting edge MRI and MRS techniques for metabolic and microstructural characterization of brain tumors with the aim of providing novel reliable noninvasive biomarkers of tumor genetic subtypes. These methods will enable noninvasive identification of IDH-mutated gliomas and, potentially, 1p/19q codeleted gliomas. In addition, the researchers will investigate the utility of 2HG, cystathionine and MRI microstructural markers to monitor tumor response to anti-cancer treatments and tumor progression.

The outputs of this project, altogether, may open new avenues to a better understanding of the pathophysiological mechanisms of oncogenesis and the design of new treatments for gliomas.