Urate is closely linked to white matter integrity in multiple system atrophy

Recent Advances in Clinical Trials in Multiple System Atrophy

PURPOSE OF REVIEW

This review summarizes previous and ongoing neuroprotection trials in multiple system atrophy (MSA), a rare and fatal neurodegenerative disease characterized by parkinsonism, cerebellar, and autonomic dysfunction. It also describes the preclinical therapeutic pipeline and provides some considerations relevant to successfully conducting clinical trials in MSA, i.e., diagnosis, endpoints, and trial design.

RECENT FINDINGS

Over 30 compounds have been tested in clinical trials in MSA. While this illustrates a strong treatment pipeline, only two have reached their primary endpoint. Ongoing clinical trials primarily focus on targeting α-synuclein, the neuropathological hallmark of MSA being α-synuclein-bearing glial cytoplasmic inclusions. The mostly negative trial outcomes highlight the importance of better understanding underlying disease mechanisms and improving preclinical models. Together with efforts to refine clinical measurement tools, innovative statistical methods, and developments in biomarker research, this will enhance the design of future neuroprotection trials in MSA and the likelihood of positive outcomes.

Diffusion Magnetic Resonance Imaging Microstructural Abnormalities in Multiple System Atrophy: A Comprehensive Review

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by autonomic failure, ataxia, and/or parkinsonism. Its prominent pathological alterations can be investigated using diffusion magnetic resonance imaging (dMRI), a technique that exploits the characteristics of water random motion inside brain tissue. The aim of this report was to review currently available literature on the application of dMRI in MSA and to describe microstructural abnormalities, diagnostic applications, and pathophysiological correlates. Sixty-four published studies involving microstructural investigation using dMRI in MSA were included. Widespread microstructural abnormalities of white matter were described, especially in the middle cerebellar peduncle, corticospinal tract, and hemispheric fibers. Gray matter degeneration was identified as well, with diffuse involvement of subcortical structures, especially in the putamina. Diagnostic applications of dMRI were mostly explored for the differential diagnosis between MSA parkinsonism and Parkinson's disease. Recently, machine learning algorithms for image processing and disease classification have demonstrated high diagnostic accuracy, showing potential for translation into clinical practice. To a lesser extent, clinical correlates of microstructural abnormalities have also been investigated, and abnormalities related to motor, ocular, and cognitive impairments were described. dMRI in MSA has contributed to in vivo identification of known pathological abnormalities. Translation into clinical practice of the latest advancements for the differential diagnosis between MSA and other forms of parkinsonism seems feasible. Current limitations involve the possibility of correctly diagnosing MSA in the very early stages, when the clinical diagnosis is most uncertain. Furthermore, pathophysiological correlates of microstructural abnormalities remain understudied. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Inosine 5'-Monophosphate to Raise Serum Uric Acid Level in Multiple System Atrophy (IMPROVE-MSA study)

The aim of this trial was to investigate the safety, tolerability, and capability of serum uric acid (UA) elevation of inosine 5'-monophosphate (IMP) in multiple system atrophy (MSA). The IMPROVE-MSA trial was a randomized, double-blind, placebo-controlled trial in patients with MSA with no history of hyperuricemia-related disorders. The participants were assigned to placebo (n = 25) or IMP (n = 30) in a 1 to 1 ratio, and then followed up for 24 weeks. The primary end points included safety, tolerability, and alteration of the serum UA level during the follow-up period. The secondary end points were changes in scores of the unified MSA rating scale (UMSARS) and the Mini-Mental Status Examination (MMSE) and Montreal Cognitive Assessment (MoCA). The total number of adverse events (AEs) and serious AEs was comparable between the active and placebo groups. Serum UA level (mg/dL) was significantly increased from baseline (active vs. placebo, 4.57 vs. 4.58; P = 0.98) to study end point (6.96 vs. 4.43; P < 0.001) in the active group compared with the placebo group (time × group interaction; P < 0.001). The change in UMSARS scores did not differ between the active and placebo groups. However, the active group showed better alterations in MoCA scores with nominal significance (P < 0.001) and tendency for better alterations in MMSE scores (P = 0.09) than the placebo group. Our data demonstrated that IMP treatment was generally safe and well-tolerated in patients with MSA. A further trial with a long-term follow-up is required to examine whether UA elevation will slow clinical progression in early MSA.