The highly heterogeneous and invasive nature characteristic of high-grade gliomas (HGG) has historically limited the efficacy of standard-of-care approaches, resulting in poor prognosis and treatment outcomes. Novel immunotherapies have shown remarkable potential to promote antitumoral immune responses and allow for long-term tumor remission. However, the complexity of the HGG tumor microenvironment and the dynamic immunological changes associated with immunotherapy response can limit the diagnostic utility of conventional magnetic resonance imaging (MRI) and positron emission tomography (PET) approaches. Consequently, distinguishing true tumor progression from immunotherapy-related effects often requires prolonged clinical follow-up over several months. To address this, novel quantitative MRI and PET-based approaches are being evaluated in preclinical studies and clinical trials. These advanced imaging methods target key biological features of the tumor microenvironment, including vascularity, cellularity, intratumoral habitats, tracer pharmacokinetics and immune infiltration, and can provide metrics to stratify patient response at earlier timepoints to support clinical decision making and improve treatment outcomes. This review highlights key HGG biological characteristics, describes standard-of-care and emerging therapeutic strategies, and discusses both conventional and advanced imaging methods to characterize immunotherapeutic responses.
Gallegos et al. (Tue,) studied this question.