Pilot Study of Repeated Blood-Brain Barrier Disruption in Patients with Mild Alzheimer's Disease with an Implantable Ultrasound Device

International audienceBackground: Temporary disruption of the blood-brain barrier (BBB) using pulsed ultrasound leads to the clearance of both amyloid and tau from the brain, increased neurogenesis, and mitigation of cognitive decline in pre-clinical models of Alzheimer’s disease (AD) while also increasing BBB penetration of therapeutic antibodies. The goal of this pilot clinical trial was to investigate the safety and the efficacy of this approach in patients with mild AD using an implantable ultrasound device. Methods: An implantable, 1 MHz ultrasound device (SonoCloud-1) was extradurally implanted under local anesthesia in the skull of 10 mild AD patients to target the left supra-marginal gyrus. Over 3.5 months, seven ultrasound sessions in combination with intravenous infusion of microbubbles were performed twice per month to temporarily disrupt the BBB. 18 F-Florbetapir and 18 F-fluorodeoxyglucose positron emission tomography (PET) imaging were performed on a combined PET/MRI scanner at inclusion and at four and eight months after initiation of sonications to monitor brain metabolism and amyloid levels along with cognitive evaluations. Evolution of cognitive and neuroimaging features were compared to that of a matched sample of control participants. Results: A total of 63 BBB opening procedures were performed in nine subjects. The procedure was well-tolerated. A non-significant decrease in amyloid accumulation at four months of -6.6% (SD=7.2%) on 18 F-Florbetapir PET imaging in the sonicated gray matter targeted by the ultrasound transducer was observed compared to baseline in six subjects that completed treatments and who had evaluable imaging scans. No differences in longitudinal change in glucose metabolism were observed compared to neighboring or contralateral regions or to the change observed in the same region in ADNI participants. No significant effect on cognition evolution was observed in comparison to the ADNI participants as expected due to the small sample size and duration of the trial. Conclusions: These results demonstrate the safety of ultrasound-based BBB disruption and potential of this technology to be used as a therapy for AD patients. They support further research of this technique in a larger clinical trial with a device designed to sonicate larger volumes of tissue and in combination with disease modifying drugs to further enhance the effects observed