Quantitative, longitudinal measurements of response to immunotherapy for glioblastoma using multiparametric MRI in a long-term survivor treated with autologous tumor lysate-loaded dendritic cell vaccine: an illustrative case.

backgroundNeurosurgeons are in the forefront of developing clinical trials that harness the immune system to combat glioblastoma. Autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) is a novel immunotherapy for glioblastoma. An unmet need is to develop a sensitive, specific, feasible, clinically relevant, neuroimaging biomarker that accurately reflects response to immunotherapy. OBSERVATIONS: This illustrative case involves a 63-year-old female who survived for 64 months following near-total resection of a glioblastoma and enrollment in a clinical trial (NCT00045968) using DCVax-L. A multivariate logistic regression model was used to assess treatment response longitudinally at 11 time points measuring predictive probability (PP) of tumor progression based on diffusion tensor imaging- and perfusion-weighted imaging-derived parameters within the contrast-enhancing region. Lesions were considered true progression (TP) if the PP was ≥ 50% and pseudoprogression (PsP; predominant treatment effects) if the PP was < 50 %. These findings were subsequently validated by histopathological analysis during resection for tumor recurrence. LESSONS: These findings support the use of multiparametric MRI to monitor the effects of immunotherapy in patients with glioblastoma. Such multiparametric prediction models using noninvasive, advanced neuroimaging may be helpful to differentiate TP from PsP in longitudinal assessment of treatment response. https://thejns.org/doi/10.3171/CASE26655.