Updated response assessment criteria for high-grade glioma: Beyond the MacDonald criteria

High-grade glioma continues to be a challenging disease with few effective treatment options and a poor prognosis, necessitating intensive research into alternate therapies. The Response Assessment in Neuro-Oncology (RANO) committee was formed to create a robust endpoint assessment criteria in Neuro-Oncology in order to streamline the assessment of new therapies in a uniform fashion. The aim of this committee is to create standardized guidelines to assess clinical and imaging response in the treatment of brain tumors, which can then be applied in clinical trials. Since the first RANO report was published in 2010, its criteria have been widely adopted and utilized in clinical trials worldwide. Standardized application of the RANO response assessment criteria in clinical trials will result in the generation of strong clinical data, which can subsequently be pooled and analyzed to attain a more accurate assessment of treatment efficacy. In this review, we summarize the current RANO guidelines in patients with high-grade glioma, highlighting the key clinical and imaging criteria used for RANO evaluation and introducing the role of newer imaging and biomarkers.