[ 68 Ga]-DOTATATE PET Standardized Uptake Value Reduction after Bevacizumab in High-grade Meningioma: A Potential Treatment Response Biomarker

Bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor A, is emerging as a promising therapy for high-grade meningioma, an aggressive central nervous system tumor with limited systemic treatment options. While clinical stabilization has been observed in prior trials, radiographic response on conventional MRI is often minimal, highlighting the need for alternative imaging biomarkers to monitor treatment effect. [68Ga]-DOTATATE is a somatostatin analog that binds with high affinity to somatostatin receptor 2, which is overexpressed in meningiomas. In this case series, we present three patients with WHO grade 3 meningioma who underwent baseline and follow-up [68Ga]-DOTATATE PET imaging in the setting of bevacizumab therapy. All patients had biopsy-confirmed high-grade disease and demonstrated multifocal [68Ga]-DOTATATE-avid lesions at baseline. Across 12 lesions, 67% showed a reduction in SUVmax following therapy. In contrast, matched control patients who underwent serial [68Ga]-DOTATATE PET imaging without bevacizumab or other systemic therapy demonstrated no significant change in SUVmax. Linear mixed-effects modeling confirmed a significant treatment effect, with a 7.2-unit greater reduction in SUVmax in the bevacizumab-treated group than in controls (p = 0.01). Our findings raise the possibility that [68Ga]-DOTATATE PET may capture early biologic responses to antiangiogenic therapy not reflected by anatomic imaging alone, potentially reflecting changes in somatostatin receptor expression, tumor perfusion, or metabolic activity. This series suggests that [68Ga]-DOTATATE PET may serve as a noninvasive, biologically informative adjunct to conventional imaging and supports further investigation of its role as a molecular imaging biomarker of bevacizumab response in high-grade meningioma.