Putaminal Recombinant Glucocerebrosidase Delivery with Magnetic Resonance–Guided Focused Ultrasound in Parkinson's Disease: A Phase I Study

ABSTRACT Background GBA1 mutation is the most common genetic risk factor for Parkinson's disease (PD). Replacement of the lysosomal enzyme glucocerebrosidase (GCase) slows neurodegeneration in PD models and may be a promising disease‐modifying therapy in patients with PD. However, recombinant GCase has limited penetration through the blood–brain barrier (BBB). Microbubble‐mediated magnetic resonance–guided focused ultrasound (MRgFUS) can reversibly disrupt the BBB for drug delivery. Methods This open‐label phase I study investigated the safety and feasibility of MRgFUS putaminal delivery of intravenous GCase at escalating doses (15 to 30 to 60 IU/kg) every 2 weeks in four patients with PD with GBA1 mutations. Results BBB permeability was achieved and restored in all patients as quantified by dynamic contrast‐enhanced magnetic resonance imaging after treatment. There were no serious adverse events. Two patients developed transient dyskinesia after treatment. Blinded Movement Disorder Society–Unified Parkinson's Disease Rating Scale motor scores off medication decreased by 12% at 6 months from baseline (from 26 ± 9 to 22 ± 6). Standardized uptake value ratio on fluorodeoxyglucose positron emission tomography imaging in the treated putamen reduced from 1.66 ± 0.14 to 1.27 ± 0.08. Conclusions Results from this study demonstrate the safety and feasibility of MRgFUS GCase delivery in PD and support further investigation of this approach. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.