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Pseudoresponse
KEY FACTS
Terminology
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Antiangiogenic agents may substantially reduce contrast enhancement in glioblastoma multiforme related to reduced vascular permeability rather than actual tumor response
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Bevacizumab (Avastin): Anti-VEGF is main antiangiogenic agent currently used for treatment of recurrent malignant gliomas
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Cediranib : VEGF receptor tyrosine kinase inhibitor has been tested in recent high-grade glioma treatment trials
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Imaging
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Decreased enhancement in patient with malignant glioma treated with anti-VEGF agent
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May see persistent FLAIR and diffusion restriction, despite decreased enhancement
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DWI and ADC have been proposed as imaging markers for tumor response in presence of antiangiogenic agents to address pseudoresponse
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Beware, decreased enhancement in tumor follow-up study may be true treatment response or pseudoresponse in setting of newer therapies
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DSC: Early changes in relative cerebral blood volume after initiation of antiangiogenic therapy may distinguish pseudoresponse from true treatment response
Top Differential Diagnoses
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Treatment response
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Steroid effect
Clinical Issues
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Antiangiogenic agents normalize hyperpermeable tumor vasculature and restore blood-brain barrier
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Local response to tumor growth is controlled, but diffuse infiltration and distant metastases are common
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Antiangiogenic agents significantly improve 6-month progression-free survival but may not affect overall survival
Axial T1 C+ MR in a GBM patient who progressed on standard therapy with radiation and Temodar shows there is a heterogeneously enhancing mass involving the genu of the corpus callosum
. Avastin therapy was started immediately after this MR examination.
. Avastin therapy was started immediately after this MR examination.
Axial T1 C+ MR in the same patient 4 weeks after the start of Avastin shows a marked decrease in the enhancing mass involving the genu of the corpus callosum
. The FLAIR and DWI showed stable hyperintensity and mass effect.
. The FLAIR and DWI showed stable hyperintensity and mass effect.
Axial T1 C+ MR in the same patient 8 weeks later shows an increase in the size of the corpus callosum enhancing mass
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Axial FLAIR MR in the same patient shows a marked increase in the size
and associated mass effect of the corpus callosum mass related to progressive tumor. Decreased enhancement on the prior MR is a result of pseudoresponse from the antiangiogenic therapy, rather than true tumor response. Diffuse tumor infiltration is common after antiangiogenic therapy.
and associated mass effect of the corpus callosum mass related to progressive tumor. Decreased enhancement on the prior MR is a result of pseudoresponse from the antiangiogenic therapy, rather than true tumor response. Diffuse tumor infiltration is common after antiangiogenic therapy.
TERMINOLOGY
Abbreviations
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Vascular endothelial growth factor (VEGF)
Synonyms
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Treatment effect, Avastin effect
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