Molecular Classification and Therapeutic Targets in Ependymoma

Simple Summary Molecular characterization of ependymoma has revolutionized its categorization. This new molecular classification has implications particularly in targeted therapeutics. Amongst the ten subgroups of ependymoma currently described, three are found in the spinal compartment, and three in the infratentorial and supratentorial compartments respectively; the subependymoma subgroup is found in all these anatomic compartments. Each subgroup carries unique molecular features that lead to oncogenesis and to disparities in prognosis. Here, the molecular classification, key clinical features, current understanding of tumorigenesis, and potential molecular targets for cranial and spinal ependymoma are discussed. Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.