MRI in Glioma Immunotherapy: Evidence, Pitfalls, and Perspectives.

Domenico Aquino,Valeria Cuccarini,Maria Grazia Bruzzone,Gaetano Finocchiaro,Andrea Gioppo

doi:10.1155/2017/5813951

Abstract

Pseudophenomena, that is, imaging alterations due to therapy rather than tumor evolution, have an important impact on the management of glioma patients and the results of clinical trials. RANO (response assessment in neurooncology) criteria, including conventional MRI (cMRI), addressed the issues of pseudoprogression after radiotherapy and concomitant chemotherapy and pseudoresponse during antiangiogenic therapy of glioblastomas (GBM) and other gliomas. The development of cancer immunotherapy forced the identification of further relevant response criteria, summarized by the iRANO working group in 2015. In spite of this, the unequivocal definition of glioma progression by cMRI remains difficult particularly in the setting of immunotherapy approaches provided by checkpoint inhibitors and dendritic cells. Advanced MRI (aMRI) may in principle address this unmet clinical need. Here, we discuss the potential contribution of different aMRI techniques and their indications and pitfalls in relation to biological and imaging features of glioma and immune system interactions.

Highlights

IntroductionGlioblastoma multiforme (GBM) is the most common primary brain tumor in adults [1] and carries a grim prognosis
Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults [1] and carries a grim prognosis.Infiltrative nature of diffuse gliomas makes it difficult to eliminate microscopic disease despite macroscopic gross total resection
The purpose of this review is to summarize current research on magnetic resonance imaging (MRI) assessment for patients undergoing immunotherapy with a major focus on Advanced MRI (aMRI) parameters

Summary

Introduction

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults [1] and carries a grim prognosis. Effective immune response might need time to evolve, and early imaging might reflect true progressive disease; on the other hand, inflammatory response in areas of macroscopic or microscopic infiltrative tumor might mimic radiological features of tumor progression with increased enhancement and edema. The iRANO committee, integrating guidance for progressive imaging findings from the irRC with RANO criteria, redefined the response assessment criteria for patients with brain tumors undergoing immunotherapy providing novel iRANO criteria [14]: in patients with early findings suggesting progression (i.e., ≥25% increase in the sum of biperpendicular diameters of enhancing tissue, development of new lesions, or substantial worsening in T2/FLAIR) within the first 6 months of immunotherapy regimen without substantial neurological decline, therapy should be continued and confirmation of radiographic progression by follow-up imaging should be sought 3 months after the initial radiographic evidence of progressive disease (Table 1, Figure 1)

Delayed-Contrast MRI

Diffusion MRI

Findings

Concluding Remarks and Perspectives