Modeling and preclinical trials for gliomas.

Glioma is the most common form of primary brain tumor. Although surgical resection of the tumor may be achieved, recurrence is almost inevitable because of the propensity of gliomas for infiltrative growth far into functionally intact brain tissue. Gliomas are classified into four clinical grades, with glioblastoma multiforme (GBM) being the most aggressive type (World Health Organization [WHO] Grade IV). GBMs develop de novo, as primary glioblastomas, or through progressive malignification of lower-grade gliomas, termed secondary glioblastomas. Gliosarcomas and giant cell glioblastomas are two rare variants that also sort into the GBM diagnosis. Diffuse gliomas (WHO Grade II) are categorized into astrocytomas, oligodendrogliomas, and mixed oligoastrocytomas, depending on the cells’ resemblance to astrocytes or oligodendrocytes. WHO Grade III gliomas constitute a more aggressive form and include anaplastic astrocytomas and anaplastic oligodendrogliomas (25).