Treatment of the later stages of Parkinson's disease - pharmacological approaches now and in the future

Recent updates on structural insights of MAO-B inhibitors: a review on target-based approach

Parkinson's disease is a neurodegenerative disorder characterized by slow movement, tremors, and stiffness caused due to loss of dopaminergic neurons caused in the brain's substantia nigra. The concentration of dopamine is decreased in the brain. Parkinson's disease may be happened because of various genetic and environmental factors. Parkinson's disease is related to the irregular expression of the monoamine oxidase (MAO) enzyme, precisely type B, which causes the oxidative deamination of biogenic amines such as dopamine. MAO-B inhibitors, available currently in the market, carry various adverse effects such as dizziness, nausea, vomiting, lightheadedness, fainting, etc. So, there is an urgent need to develop new MAO-B inhibitors with minimum side effects. In this review, we have included recently studied compounds (2018 onwards). Agrawal et al. reported MAO-B inhibitors with IC50 0.0051 µM and showed good binding affinity. Enriquez et al. reported a compound with IC50 144 nM and bind with some critical amino acid residue Tyr60, Ile198, and Ile199. This article also describes the structure-activity relationship of the compounds and clinical trial studies of related derivatives. These compounds may be used as lead compounds to develop potent compounds as MAO-B inhibitors.

Evaluation and Application of a PET Tracer in Preclinical and Phase 1 Studies to Determine the Brain Biodistribution of Minzasolmin (UCB0599)

PURPOSE

Minzasolmin (UCB0599) is an orally administered, small molecule inhibitor of ASYN misfolding in development as a potential disease-modifying therapy for Parkinson's disease. Here we describe the preclinical development of a radiolabeled tracer and results from a phase 1 study using the tracer to investigate the brain distribution of minzasolmin.

PROCEDURES

In the preclinical study, two radiolabeling positions were investigated on the S-enantiomer of minzasolmin (UCB2713): [11C]methylamine UCB2713 ([11C-N-CH3]UCB2713) and [11C]carbonyl UCB2713 ([11C-CO]UCB2713). Male C57 black 6 mice (N = 10) received intravenous [11C-N-CH3]UCB2713; brain homogenates were assessed for radioactivity and plasma samples analyzed by high-performance liquid chromatography. Positron emission tomography-computed tomography (PET-CT) was used to image brains in a subset of mice (n = 3). In the open-label, phase 1 study, healthy volunteers were scanned twice with PET-CT following injection with [11C]minzasolmin radiotracer (≤ 10 µg), first without, then with oral dosing with non-radiolabeled minzasolmin 360 mg.

PRIMARY OBJECTIVE

to determine biodistribution of minzasolmin in the human brain; secondary objectives included minzasolmin safety/tolerability.

RESULTS

Preclinical data supported the use of [11C]minzasolmin in clinical studies. In the phase 1 study, PET data showed substantial drug signal in the brain of healthy volunteers (N = 4). The mean estimated whole brain total distribution volume (VT) at equilibrium across all regions of interest was 0.512 mL/cm3, no difference in VT was observed following administration of minzasolmin 360 mg. Treatment-emergent adverse events (TEAEs) were reported by 75% (n = 3) of participants. No drug-related TEAEs, deaths, serious adverse events, or discontinuations were reported.

CONCLUSION

Following positive preclinical results with the N-methyl labeled PET tracer, [11C]minzasolmin was used in the phase 1 study, which demonstrated that minzasolmin readily crossed the blood-brain barrier and was well distributed throughout the brain. Safety and pharmacokinetic findings were consistent with previous early-phase studies (such as UP0077, NCT04875962).

Soft robotic apparel to avert freezing of gait in Parkinson's disease

Freezing of gait (FoG) is a profoundly disruptive gait disturbance in Parkinson's disease, causing unintended stops while walking. Therapies for FoG reveal modest and transient effects, resulting in a lack of effective treatments. Here we show proof of concept that FoG can be averted using soft robotic apparel that augments hip flexion. The wearable garment uses cable-driven actuators and sensors, generating assistive moments in concert with biological muscles. In this n-of-1 trial with five repeated measurements spanning 6 months, a 73-year-old male with Parkinson's disease and substantial FoG demonstrated a robust response to robotic apparel. With assistance, FoG was instantaneously eliminated during indoor walking (0% versus 39 ± 16% time spent freezing when unassisted), accompanied by 49 ± 11 m (+55%) farther walking compared to unassisted walking, faster speeds (+0.18 m s-1) and improved gait quality (-25% in gait variability). FoG-targeting effects were repeatable across multiple days, provoking conditions and environment contexts, demonstrating potential for community use. This study demonstrated that FoG was averted using soft robotic apparel in an individual with Parkinson's disease, serving as an impetus for technological advancements in response to this serious yet unmet need.

Dopaminergic regulation of inflammation and immunity in Parkinson's disease: friend or foe?

Parkinson's disease (PD) is a neurodegenerative disease affecting 7-10 million people worldwide. Currently, there is no treatment available to prevent or delay PD progression, partially due to the limited understanding of the pathological events which lead to the death of dopaminergic neurons in the substantia nigra in the brain, which is known to be the cause of PD symptoms. The current available treatments aim at compensating dopamine (DA) deficiency in the brain using its precursor levodopa, dopaminergic agonists and some indirect dopaminergic agents. The immune system is emerging as a critical player in PD. Therefore, immune-based approaches have recently been proposed to be used as potential antiparkinsonian agents. It has been well-known that dopaminergic pathways play a significant role in regulating immune responses in the brain. Although dopaminergic agents are the primary antiparkinsonian treatments, their immune regulatory effect has yet to be fully understood. The present review summarises the current available evidence of the immune regulatory effects of DA and its mimics and discusses dopaminergic agents as antiparkinsonian drugs. Based on the current understanding of their involvement in the regulation of neuroinflammation in PD, we propose that targeting immune pathways involved in PD pathology could offer a better treatment outcome for PD patients.

Targeting mitochondrial dysfunction to salvage cellular senescence for managing neurodegeneration

Aging is an inevitable phenomenon that causes a decline in bodily functions over time. One of the most important processes that play a role in aging is senescence. Senescence is characterized by accumulation of cells that are no longer functional but elude the apoptotic pathway. These cells secrete inflammatory molecules that comprise the senescence associated secretory phenotype (SASP). Several essential molecules such as p53, Rb, and p16INK4a regulate the senescence process. Mitochondrial regulation has been found to play an important role in senescence. Reactive oxygen species (ROS) generated from mitochondria can affect cellular senescence by inducing the persistent DNA damage response, thus stabilizing the senescence. Evidently, senescence plays a major contributory role to the development of age-related neurological disorders. In this chapter, we discuss the role of senescence in the progression and onset of several neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Moreover, we also discuss the efficacy of certain molecules like MitoQ, SkQ1, and Latrepirdine that could be proven therapeutics with respect to these disorders by regulating mitochondrial activity.

Effects of Music-Based Interventions on Motor and Non-Motor Symptoms in Patients with Parkinson's Disease: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis examined previous studies on music-based interventions for individuals with Parkinson’s disease (PD). The effectiveness of the interventions on various motor and non-motor outcomes was evaluated. This review was conducted by searching PubMed, CINAHL, PsycINFO, and Cochrane Library CENTRAL prior to June 2022 for randomized controlled trial (RCT) and controlled clinical trial (CCT) studies published in English. Data were expressed as weighted/standardized mean difference (MD/SMD) with 95% confidence intervals (CI). I2 index was used for heterogeneity. The initial search identified 745 studies, and 13 studies involving 417 participants with PD which met the inclusion criteria included in this review. The results of the meta-analysis revealed that music-based interventions can significantly improve walking velocity (MD = 0.12, 95% CI = 0.07~0.16, p < 0.00001), stride length (MD = 0.04, 95% CI = 0.02~0.07, p = 0.002), and mobility (MD = −1.05, 95% CI = −1.53~−0.57, p < 0.0001). However, the results did not support significant effects for music-based interventions on cadence (MD = 3.21, 95% CI = −4.15~10.57, p = 0.39), cognitive flexibility (MD = 20.91, 95% CI = −10.62~52.44, p = 0.19), inhibition (SMD = 0.07, 95% CI = −0.40~0.55, p = 0.76), and quality of life (SMD = −0.68, 95% CI= −1.68~0.32, p = 0.18). The findings suggest that music-based interventions are effective for the improvement of some motor symptoms, but evidence for non-motor symptoms is limited. Further high-quality studies with a larger sample size are required to obtain the robust effects of music-based interventions on various outcomes among patients with PD.

The PPN and motor control: Preclinical studies to deep brain stimulation for Parkinson's disease

The pedunculopontine nucleus (PPN) is the major part of the mesencephalic locomotor region, involved in the control of gait and locomotion. The PPN contains glutamatergic, cholinergic, and GABAergic neurons that all make local connections, but also have long-range ascending and descending connections. While initially thought of as a region only involved in gait and locomotion, recent evidence is showing that this structure also participates in decision-making to initiate movement. Clinically, the PPN has been used as a target for deep brain stimulation to manage freezing of gait in late Parkinson's disease. In this review, we will discuss current thinking on the role of the PPN in locomotor control. We will focus on the cytoarchitecture and functional connectivity of the PPN in relationship to motor control.

Phase 1/1b Studies of UCB0599, an Oral Inhibitor of α-Synuclein Misfolding, Including a Randomized Study in Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) and its progression are thought to be caused and driven by misfolding of α-synuclein (ASYN). UCB0599 is an oral, small-molecule inhibitor of ASYN misfolding, aimed at slowing disease progression.

OBJECTIVE

The aim was to investigate safety/tolerability and pharmacokinetics (PK) of single and multiple doses of UCB0599.

METHODS

Safety/tolerability and PK of single and multiple doses of UCB0599 and its metabolites were investigated in two phase 1 studies in healthy participants (HPs), where food effect and possible interaction with itraconazole (ITZ) were assessed (UP0030 [randomized, placebo-controlled, dose-escalation, crossover study, N = 65] and UP0078 [open-label study, N = 22]). Safety/tolerability and multi-dose PK of UCB0599 were subsequently investigated in a phase 1b randomized, double-blind, placebo-controlled study of participants with PD (UP0077 [NCT04875962], N = 31).

RESULTS

Across all studies, UCB0599 displayed rapid absorption with linear, time-independent PK properties; PK of multiple doses of UCB0599 were predictable from single-dose exposures. No notable food-effect was observed; co-administration with ITZ affected UCB0599 disposition (maximum plasma concentration and area under the curve increased ~1.3- and ~2 to 3-fold, respectively) however, this did not impact the safety profile. Hypersensitivity reactions were reported in UP0030 (n = 2) and UP0077 (n = 2). Treatment-related adverse events occurred in 43% (UCB0599), and 30% (placebo) of participants with PD were predominantly mild-to-moderate in intensity and were not dose related.

CONCLUSIONS

Seventy-three HPs and 21 participants with PD received UCB0599 doses; an acceptable safety/tolerability profile and predictable PK support continued development of UCB0599 for the slowing of PD progression. A phase 2 study in early-stage PD is underway (NCT04658186). © 2022 UCB Pharma. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Deep brain stimulation for Parkinson’s Disease: A Review and Future Outlook

Parkinson's Disease (PD) is a neurodegenerative disorder that manifests as an impairment of motor and non-motor abilities due to a loss of dopamine input to deep brain structures. While there is presently no cure for PD, a variety of pharmacological and surgical therapeutic interventions have been developed to manage PD symptoms. This review explores the past, present and future outlooks of PD treatment, with particular attention paid to deep brain stimulation (DBS), the surgical procedure to deliver DBS, and its limitations. Finally, our group's efforts with respect to brain mapping for DBS targeting will be discussed.

A Phase II Study to Evaluate the Safety and Efficacy of Prasinezumab in Early Parkinson's Disease (PASADENA): Rationale, Design, and Baseline Data

Background: Currently available treatments for Parkinson's disease (PD) do not slow clinical progression nor target alpha-synuclein, a key protein associated with the disease. Objective: The study objective was to evaluate the efficacy and safety of prasinezumab, a humanized monoclonal antibody that binds aggregated alpha-synuclein, in individuals with early PD. Methods: The PASADENA study is a multicenter, randomized, double-blind, placebo-controlled treatment study. Individuals with early PD, recruited across the US and Europe, received monthly intravenous doses of prasinezumab (1,500 or 4,500 mg) or placebo for a 52-week period (Part 1), followed by a 52-week extension (Part 2) in which all participants received active treatment. Key inclusion criteria were: aged 40-80 years; Hoehn & Yahr (H&Y) Stage I or II; time from diagnosis ≤2 years; having bradykinesia plus one other cardinal sign of PD (e.g., resting tremor, rigidity); DAT-SPECT imaging consistent with PD; and either treatment naïve or on a stable monoamine oxidase B (MAO-B) inhibitor dose. Study design assumptions for sample size and study duration were built using a patient cohort from the Parkinson's Progression Marker Initiative (PPMI). In this report, baseline characteristics are compared between the treatment-naïve and MAO-B inhibitor-treated PASADENA cohorts and between the PASADENA and PPMI populations. Results: Of the 443 patients screened, 316 were enrolled into the PASADENA study between June 2017 and November 2018, with an average age of 59.9 years and 67.4% being male. Mean time from diagnosis at baseline was 10.11 months, with 75.3% in H&Y Stage II. Baseline motor and non-motor symptoms (assessed using Movement Disorder Society-Unified Parkinson's Disease Rating Scale [MDS-UPDRS]) were similar in severity between the MAO-B inhibitor-treated and treatment-naïve PASADENA cohorts (MDS-UPDRS sum of Parts I + II + III [standard deviation (SD)]; 30.21 [11.96], 32.10 [13.20], respectively). The overall PASADENA population (63.6% treatment naïve and 36.4% on MAO-B inhibitor) showed a similar severity in MDS-UPDRS scores (e.g., MDS-UPDRS sum of Parts I + II + III [SD]; 31.41 [12.78], 32.63 [13.04], respectively) to the PPMI cohort (all treatment naïve). Conclusions: The PASADENA study population is suitable to investigate the potential of prasinezumab to slow disease progression in individuals with early PD. Trial Registration: NCT03100149.

Emerging hiPSC Models for Drug Discovery in Neurodegenerative Diseases

Neurodegenerative diseases affect millions of people worldwide and are characterized by the chronic and progressive deterioration of neural function. Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD), represent a huge social and economic burden due to increasing prevalence in our aging society, severity of symptoms, and lack of effective disease-modifying therapies. This lack of effective treatments is partly due to a lack of reliable models. Modeling neurodegenerative diseases is difficult because of poor access to human samples (restricted in general to postmortem tissue) and limited knowledge of disease mechanisms in a human context. Animal models play an instrumental role in understanding these diseases but fail to comprehensively represent the full extent of disease due to critical differences between humans and other mammals. The advent of human-induced pluripotent stem cell (hiPSC) technology presents an advantageous system that complements animal models of neurodegenerative diseases. Coupled with advances in gene-editing technologies, hiPSC-derived neural cells from patients and healthy donors now allow disease modeling using human samples that can be used for drug discovery.

Psychomotor impairments and therapeutic implications revealed by a mutation associated with infantile Parkinsonism-Dystonia

Parkinson disease (PD) is a progressive, neurodegenerative disorder affecting over 6.1 million people worldwide. Although the cause of PD remains unclear, studies of highly penetrant mutations identified in early-onset familial parkinsonism have contributed to our understanding of the molecular mechanisms underlying disease pathology. Dopamine (DA) transporter (DAT) deficiency syndrome (DTDS) is a distinct type of infantile parkinsonism-dystonia that shares key clinical features with PD, including motor deficits (progressive bradykinesia, tremor, hypomimia) and altered DA neurotransmission. Here, we define structural, functional, and behavioral consequences of a Cys substitution at R445 in human DAT (hDAT R445C), identified in a patient with DTDS. We found that this R445 substitution disrupts a phylogenetically conserved intracellular (IC) network of interactions that compromise the hDAT IC gate. This is demonstrated by both Rosetta molecular modeling and fine-grained simulations using hDAT R445C, as well as EPR analysis and X-ray crystallography of the bacterial homolog leucine transporter. Notably, the disruption of this IC network of interactions supported a channel-like intermediate of hDAT and compromised hDAT function. We demonstrate that Drosophila melanogaster expressing hDAT R445C show impaired hDAT activity, which is associated with DA dysfunction in isolated brains and with abnormal behaviors monitored at high-speed time resolution. We show that hDAT R445C Drosophila exhibit motor deficits, lack of motor coordination (i.e. flight coordination) and phenotypic heterogeneity in these behaviors that is typically associated with DTDS and PD. These behaviors are linked with altered dopaminergic signaling stemming from loss of DA neurons and decreased DA availability. We rescued flight coordination with chloroquine, a lysosomal inhibitor that enhanced DAT expression in a heterologous expression system. Together, these studies shed some light on how a DTDS-linked DAT mutation underlies DA dysfunction and, possibly, clinical phenotypes shared by DTDS and PD.

Exploring Nonmotor Neuropsychiatric Manifestations of Parkinson Disease in a Comprehensive Care Setting

Parkinson disease (PD) is a debilitating neurological condition that includes both motor symptoms and nonmotor symptoms (NMS). Psychiatric complaints comprise NMS and are collectively referred to as neuropsychiatric manifestations. Common findings include atypical depressive symptoms, anxiety, psychosis, impulse control disorder, deterioration of cognition, and sleep disturbances. Quality of life (QoL) of patients suffering from NMS is greatly impacted and many times can be more debilitating than motor symptoms of PD. We expand on knowledge gained from treatment models within a comprehensive care model that incorporates multidisciplinary specialists working alongside psychiatrists to treat PD. Insight into background, clinical presentations, and treatment options for patients suffering from neuropsychiatric manifestations of PD are discussed. Identifying symptoms early can help improve QoL, provide early symptom relief, and can assist tailoring treatment plans that limit neuropsychiatric manifestations.

Gait Progression Over 6 Years in Parkinson's Disease: Effects of Age, Medication, and Pathology

Background: Gait disturbance is an early, cardinal feature of Parkinson's disease (PD) associated with falls and reduced physical activity. Progression of gait impairment in Parkinson's disease is not well characterized and a better understanding is imperative to mitigate impairment. Subtle gait impairments progress in early disease despite optimal dopaminergic medication. Evaluating gait disturbances over longer periods, accounting for typical aging and dopaminergic medication changes, will enable a better understanding of gait changes and inform targeted therapies for early disease. This study aimed to describe gait progression over the first 6 years of PD by delineating changes associated with aging, medication, and pathology. Methods: One-hundred and nine newly diagnosed PD participants and 130 controls completed at least two gait assessments. Gait was assessed at 18-month intervals for up to 6 years using an instrumented walkway to measure sixteen spatiotemporal gait characteristics. Linear mixed-effects models assessed progression. Results: Ten gait characteristics significantly progressed in PD, with changes in four of these characteristics attributable to disease progression. Age-related changes also contributed to gait progression; changes in another two characteristics reflected both aging and disease progression. Gait impairment progressed irrespective of dopaminergic medication change for all characteristics except step width variability. Conclusions: Discrete gait impairments continue to progress in PD over 6 years, reflecting a combination of, and potential interaction between, disease-specific progression and age-related change. Gait changes were mostly unrelated to dopaminergic medication adjustments, highlighting limitations of current dopaminergic therapy and the need to improve interventions targeting gait decline.

Mechanisms and Pharmacotherapy for Ethanol-Responsive Movement Disorders

Ethanol-responsive movement disorders are a group of movement disorders of which clinical manifestation could receive significant improvement after ethanol intake, including essential tremor, myoclonus-dystonia, and some other hyperkinesia. Emerging evidence supports that the sensitivity of these conditions to ethanol might be attributed to similar anatomical targets and pathophysiologic mechanisms. Cerebellum and cerebellum-related networks play a critical role in these diseases. Suppression of inhibitory neurotransmission and hyper-excitability of these regions are the key points for pathogenesis. GABA pathways, the main inhibitory system involved in these regions, were firstly linked to the pathogenesis of these diseases, and GABAA receptors and GABAB receptors play critical roles in ethanol responsiveness. Moreover, impairment of low-voltage-activated calcium channels, which were considered as a contributor to oscillation activity of the nervous system, also participates in the sensitivity of ethanol in relevant disease. Glutamate transporters and receptors that are closely associated with GABA pathways are the action sites for ethanol as well. Accordingly, alternative medicines aiming at these shared mechanisms appeared subsequently to mimic ethanol-like effects with less liability, and some of them have achieved positive effects on different diseases with well-tolerance. However, more clinical trials with a large sample and long-term follow-ups are needed for pragmatic use of these medicines, and further investigations on mechanisms will continue to deepen the understanding of these diseases and also accelerate the discovery of ideal treatment.

Motor impulsivity and delay intolerance are elicited in a dose-dependent manner with a dopaminergic agonist in parkinsonian rats

RATIONALE

Impulse control disorders (ICD) and other impulsive-compulsive behaviours are frequently found in Parkinson's disease (PD) patients treated with dopaminergic agonists. To date, there are no available animal models to investigate their pathophysiology and determine whether they can be elicited by varying doses of dopaminergic drugs. In addition, there is some controversy regarding the predispositional pattern of striatal dopaminergic depletion.

OBJECTIVES

To study the effect of two doses of pramipexole (PPX) on motor impulsivity, delay intolerance and compulsive-like behaviour.

METHODS

Male rats with mild dopaminergic denervation in the dorsolateral striatum (bilateral injections of 6-hydroxidopamine (6-OHDA)) treated with two doses of PPX (0.25 mg/kg and 3 mg/kg) and tested in the variable delay-to-signal paradigm.

RESULTS

Partial (50%) dopaminergic depletion did not induce significant changes in motor impulsivity or delay intolerance. However, 0.25 mg/kg of PPX increased motor impulsivity, while 3 mg/kg of PPX increased both motor impulsivity and delay intolerance. These effects were independent of the drug's antiparkinsonian effects. Importantly, impulsivity scores before and after dopaminergic lesion were positively associated with the impulsivity observed after administering 3 mg/kg of PPX. No compulsive-like behaviour was induced by PPX administration.

CONCLUSIONS

We described a rat model, with a moderate dorsolateral dopaminergic lesion resembling that suffered by patients with early PD, that develops different types of impulsivity in a dose-dependent manner dissociated from motor benefits when treated with PPX. This model recapitulates key features of abnormal impulsivity in PD and may be useful for deepening our understanding of the pathophysiology of ICD.

A Network Pharmacology-Based Study of the Molecular Mechanisms of Shaoyao-Gancao Decoction in Treating Parkinson's Disease

Parkinson's disease (PD) is another major neurodegenerative disorder following Alzheimer's disease, which not only seriously reduces the survival in patients, affecting patient's quality of life, but also imposes a tremendous burden on families and even the whole society. It is urgent to find out effective drugs without side effects. The present study applied a creative approach called network pharmacology to explore the active compounds and therapeutic targets of Shaoyao-Gancao Decoction (SYGCD) for treating PD. We identified a total of 48 active compounds mediating 30 PD-related targets to exert synergism, and the same target can be enriched in multiple signal pathways and biological processes, expounding that the decoction can exert synergistic effect on PD by multi-targets and multi-pathways. Furthermore, the molecular docking analysis showed that active compounds and targets can be well combined. These results highlighted the molecular mechanisms underlying the efficiency of SYGCD for PD treatment at a systematic level, investigating thoroughly the innovative therapeutic tactics for PD in traditional Chinese medicine.

Effectiveness of a Goal-Based Intensive Rehabilitation in Parkinsonian Patients in Advanced Stages of Disease

BACKGROUND

Parkinsonian patients in advanced stages of disease suffer from many motor and non-motor symptoms, whose responsiveness to dopamine replacement therapy and deep brain stimulation is poor. It is necessary to find complementary strategies in order to improve the clinical conditions of patients in advanced Parkinson's disease (PD) stages.

OBJECTIVE

We aimed to understand whether an inpatient, motor-cognitive, multidisciplinary, aerobic, intensive and goal-based rehabilitation treatment (MIRT), specifically designed for PD, is effective for patients in advanced stages of disease.

METHODS

638 Parkinsonian patients, hospitalized to undergo a 4-week MIRT, were retrospectively identified. According to the Hoehn & Yahr (H&Y) scale, 496 were in H&Y stage 3 and 142 in H&Y stage 4-5. Outcome measures included: Unified Parkinson's Disease Rating Scale (UPDRS), Berg Balance Scale (BBS), Timed Up and Go Test (TUG), Six Minute Walk Test (6MWT), and Parkinson's Disease Disability Scale (PDDS).

RESULTS

At baseline all measures, except UPDRS IV, significantly worsened passing from H&Y stage 3 to H&Y stage 4-5 (p≤0.002 all). After rehabilitation all outcome measures significantly improved in both groups of patients (p < 0.0001 all). Comparing the amount of improvement in the two groups, significant differences were observed only for the changes in BBS and TUG (both p < 0.0001 after adjustment), with a better improvement in the H&Y stage 4-5 group.

CONCLUSIONS

A multidisciplinary, motor-cognitive, intensive and goal-based rehabilitation treatment, such as MIRT, could be an effective complementary treatment in PD patients in advanced stages of disease.

Are There Benefits in Adding Catechol-O Methyltransferase Inhibitors in the Pharmacotherapy of Parkinson's Disease Patients? A Systematic Review

BACKGROUND

A qualified consensus suggests that a combination of levodopa with a peripherally acting dopa decarboxylase inhibitor continues to present the gold standard treatment of Parkinson's disease (PD). However, as the disease progresses the therapeutic window of levodopa becomes narrowed. Pharmacological strategies for motor fluctuations are focused on providing less pulsatile and more continuous dopaminergic stimulation. Peripheral catechol-O-methyltransferase (COMT) inhibition improves the bioavailability of levodopa and results in a prolonged response.

OBJECTIVE

The primary aim of this study was to investigate the efficacy and safety of the two available COMT inhibitors; entacapone and tolcapone and the recently introduced opicapone.

METHODS

Electronic databases were systematically searched for original studies published within the last 37 years. In addition, lists of identified studies, reviews and their references were examined.

RESULTS

Twelve studies fulfilled the inclusion criteria. 3701 patients with PD were included in this systematic review.

CONCLUSIONS

Adjuvant treatment of PD patients experiencing motor fluctuations with entacapone resulted in improvement of motor function and was well tolerated. Therefore, entacapone presented an acceptable benefit to risk ratio. Tolcapone appeared to result in a greater therapeutic effect. However, this was not consistent across all motor variables and studies, and thus would not support its use, given the current onerous monitoring that is required. Opicapone was not associated with adverse reactions in a phase III trial but did not present a greater efficacy than entacapone, and thus further studies are required in order to illustrate its cost effectiveness.

Potential Therapeutic Application for Nicotinic Receptor Drugs in Movement Disorders

Emerging studies indicate that striatal cholinergic interneurons play an important role in synaptic plasticity and motor control under normal physiological conditions, while their disruption may lead to movement disorders. Here we discuss the involvement of the cholinergic system in motor dysfunction, with a focus on the role of the nicotinic cholinergic system in Parkinson's disease and drug-induced dyskinesias. Evidence for a role for the striatal nicotinic cholinergic system stems from studies showing that administration of nicotine or nicotinic receptor drugs protects against nigrostriatal degeneration and decreases L-dopa-induced dyskinesias. In addition, nicotinic receptor drugs may ameliorate tardive dyskinesia, Tourette's syndrome and ataxia, although further study is required to understand their full potential in the treatment of these disorders. A role for the striatal muscarinic cholinergic system in movement disorders stems from studies showing that muscarinic receptor drugs acutely improve Parkinson's disease motor symptoms, and may reduce dyskinesias and dystonia. Selective stimulation or lesioning of striatal cholinergic interneurons suggests they are primary players in this regulation, although multiple central nervous systems appear to be involved.

IMPLICATIONS

Accumulating data from preclinical studies and clinical trials suggest that drugs targeting CNS cholinergic systems may be useful for symptomatic treatment of movement disorders. Nicotinic cholinergic drugs, including nicotine and selective nAChR receptor agonists, reduce L-dopa-induced dyskinesias, as well as antipsychotic-induced tardive dyskinesia, and may be useful in Tourette's syndrome and ataxia. Subtype selective muscarinic cholinergic drugs may also provide effective therapies for Parkinson's disease, dyskinesias and dystonia. Continued studies/trials will help address this important issue.

Herbal Medicine Formulas for Parkinson's Disease: A Systematic Review and Meta-Analysis of Randomized Double-Blind Placebo-Controlled Clinical Trials

Background: Parkinson's disease (PD) is a debitlitating, chronic, progressive neurodegenerative disorder without modifying therapy. Here, we aimed to evaluate the available evidence of herbal medicine (HM) formulas for patients with PD according to randomized double-blind placebo-controlled clinical trials. Methods: HM formulas for PD were searched in eight main databases from their inception to February 2018. The methodological quality was assessed using Cochrane Collaboration risk of bias tool. Meta-analysis was performed using RevMan 5.3 software. Results: Fourteen trials with Seventeen comparisons comprising 1,311 patients were identified. Compared with placebo groups, HM paratherapy (n = 16 comparisons) showed significant better effects in the assessments of total Unified Parkinson's Disease Rating Scale (UPDRS) (WMD: -5.43, 95% CI:-8.01 to -2.86; P < 0.0001), UPDRS I (WMD: -0.30, 95% CI: -0.54 to -0.06; P = 0.02), UPDRS II (WMD: -2.21, 95% CI: -3.19 to -1.22; P < 0.0001), UPDRS III (WMD: -3.26, 95% CI:-4.36 to -2.16; P < 0.00001), Parkinson's Disease Quality of Life Questionnaire (p < 0.01) and Parkinson's Disease Questionnaire-39 (WMD: -7.65, 95% CI: -11.46 to -3.83; p < 0.0001), Non-motor Symptoms Questionnaire (p < 0.01) and Non-Motor Symptoms Scale (WMD: -9.19, 95% CI: -13.11 to -5.28; P < 0.00001), Parkinson's Disease Sleep Scale (WMD: 10.69, 95% CI: 8.86 to 12.53; P < 0.00001), and Hamilton depression rating scale (WMD: -5.87, 95% CI: -7.06 to -4.68; P < 0.00001). The efficiency of HM monotherapy (n = 1 comparison) was not superior to the placebo according to UPDRS II, UPDRS III and total UPDRS score in PD patients who never received levodopa treatment, all P > 0.05. HM formulas paratherapy were generally safe and well tolerated for PD patients (RR: 0.41, 95% CI: 0.21 to 0.80; P = 0.009). Conclusion: The findings of present study supported the complementary use of HM paratherapy for PD patients, whereas the question on the efficacy of HM monotherapy in alleviating PD symptoms is still open.

Adjunct rasagiline to treat Parkinson's disease with motor fluctuations: a randomized, double-blind study in China

Background

The use of adjunct rasagiline in levodopa-treated patients with Parkinson’s disease and motor fluctuations is supported by findings from large-scale clinical studies. This study is to investigate the efficacy and safety of adjunct rasagiline in Chinese patients with Parkinson’s disease, as a product registration study.

Methods

This 16-week, randomized, double-blind, parallel-group, multicenter, placebo-controlled study of rasagiline 1 mg/day included levodopa-treated patients with Parkinson’s disease and motor fluctuations. The primary efficacy endpoint was mean change from baseline in total daily OFF time over 16 weeks. Secondary endpoints were Clinical Global Impressions – Improvement (CGI-I), and change in Unified Parkinson’s Disease Rating Scale (UPDRS) Activities of daily living (ADL) and Motor scores. Patient well-being (EQ-5D), and the frequency of adverse events were also assessed.

Results

In total, 324 levodopa-treated patients were randomized to rasagiline 1 mg/day (n = 165) or placebo (n = 159). Over 16 weeks, rasagiline statistically significantly reduced the mean [95% confidence interval] total daily OFF time versus placebo (− 0.5 h [− 0.92, − 0.07]; p = 0.023). There were also statistically significant improvements versus placebo in CGI-I (− 0.4 points [− 0.61, − 0.22]; p < 0.001), UPDRS-ADL OFF (− 1.0 points [− 1.75, − 0.27]; p = 0.008), and UPDRS-Motor ON (− 1.6 points [− 3.05, − 0.14]; p = 0.032) scores, as well as the EQ-5D utility index (p < 0.05). Rasagiline was safe and well tolerated.

Conclusions

In levodopa-treated Chinese patients with Parkinson’s disease and motor fluctuations, adjunct rasagiline 1 mg/day statistically significantly reduced OFF time, and improved daily function and overall well-being, versus placebo. Consistent with findings in other countries, adjunct rasagiline was proven efficacious and well tolerated in Chinese patients.

Trial registration number

NCT01479530. Registered 22 November 2011.

Current Nondopaminergic Therapeutic Options for Motor Symptoms of Parkinson's Disease

Objective:

The aim of this study was to summarize recent studies on nondopaminergic options for the treatment of motor symptoms in Parkinson's disease (PD).

Data Sources:

Papers in English published in PubMed, Cochrane, and Ovid Nursing databases between January 1988 and November 2016 were searched using the following keywords: PD, nondopaminergic therapy, adenosine, glutamatergic, adrenergic, serotoninergic, histaminic, and iron chelator. We also reviewed the ongoing clinical trials in the website of clinicaltrials.gov.

Study Selection:

Articles related to the nondopaminergic treatment of motor symptoms in PD were selected for this review.

Results:

PD is conventionally treated with dopamine replacement strategies, which are effective in the early stages of PD. Long-term use of levodopa could result in motor complications. Recent studies revealed that nondopaminergic systems such as adenosine, glutamatergic, adrenergic, serotoninergic, histaminic, and iron chelator pathways could include potential therapeutic targets for motor symptoms, including motor fluctuations, levodopa-induced dyskinesia, and gait disorders. Some nondopaminergic drugs, such as istradefylline and amantadine, are currently used clinically, while most such drugs are in preclinical testing stages. Transitioning of these agents into clinically beneficial strategies requires reliable evaluation since several agents have failed to show consistent results despite positive findings at the preclinical level.

Conclusions:

Targeting nondopaminergic transmission could improve some motor symptoms in PD, especially the discomfort of dyskinesia. Although nondopaminergic treatments show great potential in PD treatment as an adjunct therapy to levodopa, further investigation is required to ensure their success.

The effect of Banisteriopsis caapi (B. caapi) on the motor deficits in the MPTP-treated common marmoset model of Parkinson's disease

Banisteriopsis caapi (B. caapi) contains harmine, harmaline, and tetrahydroharmine, has monoamine oxidase inhibitory activity, and has reported antiparkinsonian activity in humans when imbibed as a tea; however, its effects are poorly documented. For this reason, motor function was assessed in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets following administration of B. caapi extract (28.4-113.6 mg/kg; po), harmine (0.1 and 0.3 mg/kg; sc), and selegiline (10 mg/kg; sc), alone or with a submaximal dose of L-3,4-dihydroxyphenylalanine (L-DOPA; 4-7 mg/kg). L-DOPA reversed motor disability, increased locomotor activity, and induced moderate dyskinesia. B. caapi did not increase locomotor activity or induce dyskinesia but at 56.8 and 113.6 mg/kg improved motor disability. The L-DOPA response was unaltered by co-administration of B. caapi. Harmine (0.1 and 0.3 mg/kg) produced a mild improvement in motor disability without affecting locomotor activity or dyskinesia but had no effect on the L-DOPA-induced antiparkinsonian response. Selegiline (10 mg/kg) alone improved motor function to the same extent as L-DOPA, but with only mild dyskinesia, and did not alter the response to L-DOPA, although dyskinesia was reduced. The findings suggest that B. caapi alone has a mild antiparkinsonian effect but does not enhance the L-DOPA response or reduce dyskinesia.

Pulmonary Safety and Tolerability of Inhaled Levodopa (CVT-301) Administered to Patients with Parkinson's Disease

Background: CVT-301, an inhaled levodopa (LD) formulation, is under development for relief of OFF periods in Parkinson's disease (PD). Previously, we reported that CVT-301 improved OFF symptoms relative to placebo. In this study, we evaluate pulmonary function in patients treated with a single dose of CVT-301 or placebo for 3 hours, or received multiple doses/day for 4 weeks.

Methods: As part of two phase 2 studies, pulmonary safety and tolerability of CVT-301 were evaluated in PD patients experiencing motor fluctuations (≥2 hours OFF/day), Hoehn and Yahr stage 1–3, and forced expiratory volume in 1 second/forced vital capacity ratio ≥75% of predicted (in ON state). In study A, patients received single doses of oral carbidopa/LD and each of the following via the inhaled route: placebo and 25 and 50 mg LD fine particle dose (FPD) CVT-301. In study B, patients received up to 3 inhaled doses/day of 35 mg (weeks 1–2) and 50 mg LD FPD CVT-301 (weeks 3–4) versus placebo. Assessments included spirometry and treatment-emergent adverse events (TEAEs).

Results: In study A, (n = 24) mean age ± standard deviation was 61.3 ± 7.4 years, mean time since diagnosis was 10.5 ± 4.6 years, and mean duration of LD treatment 8.4 ± 3.7 years. Assessment of pulmonary function (predose to 3 hours postdose) showed that spirometry findings were within normal ranges, regardless of treatment groups, or motor status at screening. In study B, (n = 86) mean age was 62.4 ± 8.7 years, time since PD diagnosis was 9.4 ± 3.9 years, and duration of LD treatment 7.8 ± 3.9 years. Longitudinal assessment of pulmonary function over 4 weeks showed no significant difference in spirometry between CVT-301 versus placebo groups. In both studies, the most common CVT-301 TEAE was mild-to-moderate cough (study A: 21%; study B: 7% vs. 2% in placebo). Other common TEAEs in study B were dizziness and nausea.

Conclusion: Acute and longitudinal assessment of pulmonary function showed that CVT-301 treatment was not associated with acute airflow obstruction in this population. CVT-301 was generally safe and well tolerated.

Pharmacokinetics and brain uptake study of novel AMPA receptor antagonist perampanel in SD rats using a validated UHPLC-QTOF-MS method

Perampanel (PER) is a novel AMPA receptor antagonist for antiepileptic therapy and is prospective for the treatment of other neurological disorders. A highly sensitive and rapid UHPLC-QTOF-MS method was developed for the quantification of PER in plasma/brain homogenate of SD rat with alogliptin as an internal standard (IS). Chromatographic separation was carried out on an Acquity UPLC HSS Cyano column (100mm×2.1mm, 1.8μm) using gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0. 4mL/min. Sample preparation was carried out by a simple protein precipitation method. The mass spectrometric analysis of target ions at [M+H]⁺m/z 350.1288 for PER and m/z 340.1779 for IS was monitored with extracted ion chromatography. The developed analytical method meets the US-FDA and EMA bioanalytical guidelines and was found to be precise, accurate, selective and rugged. It exhibited good sensitivity (0.4ng/mL) and linearity over a range of 0.4-400ng/mL in both the bio-matrices. The method was successfully applied to pharmacokinetics and brain uptake study of PER after oral administration to SD rats. The study results showed PER has penetrated the blood-brain barrier, brain to plasma ratio (Kp) was found to be 0.62±0.05 and its rapidly eliminated from the brain.

Long-term Efficacy of Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease: A 5-year Follow-up Study in China

Background:

Subthalamic nucleus deep brain stimulation (STN DBS) is effective against advanced Parkinson's disease (PD), allowing dramatic improvement of Parkinsonism, in addition to a significant reduction in medication. Here we aimed to investigate the long-term effect of STN DBS in Chinese PD patients, which has not been thoroughly studied in China.

Methods:

Ten PD patients were assessed before DBS and followed up 1, 3, and 5 years later using Unified Parkinson's Disease Rating Scale Part III (UPDRS III), Parkinson's Disease Questionnatire-39, Parkinson's Disease Sleep Scale-Chinese Version, Mini-mental State Examination, Montreal Cognitive Assessment, Hamilton Anxiety Scale and Hamilton Depression Scale. Stimulation parameters and drug dosages were recorded at each follow-up. Data were analyzed using the ANOVA for repeated measures.

Results:

In the “off” state (off medication), DBS improved UPDRS III scores by 35.87% in 5 years, compared with preoperative baseline (P < 0.001). In the “on” state (on medication), motor scores at 5 years were similar to the results of preoperative levodopa challenge test. The quality of life is improved by 58.18% (P < 0.001) from baseline to 3 years and gradually declined afterward. Sleep, cognition, and emotion were mostly unchanged. Levodopa equivalent daily dose was reduced from 660.4 ± 210.1 mg at baseline to 310.6 ± 158.4 mg at 5 years (by 52.96%, P < 0.001). The average pulse width, frequency and amplitude at 5 years were 75.0 ± 18.21 μs, 138.5 ± 19.34 Hz, and 2.68 ± 0.43 V, respectively.

Conclusions:

STN DBS is an effective intervention for PD, although associated with a slightly diminished efficacy after 5 years. Compared with other studies, patients in our study required lower voltage and medication for satisfactory symptom control.

Induced pluripotent stem cells and Parkinson's disease: modelling and treatment

Many neurodegenerative disorders, such as Parkinson's disease (PD), are characterized by progressive neuronal loss in different regions of the central nervous system, contributing to brain dysfunction in the relevant patients. Stem cell therapy holds great promise for PD patients, including with foetal ventral mesencephalic cells, human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Moreover, stem cells can be used to model neurodegenerative diseases in order to screen potential medication and explore their mechanisms of disease. However, related ethical issues, immunological rejection and lack of canonical grafting protocols limit common clinical use of stem cells. iPSCs, derived from reprogrammed somatic cells, provide new hope for cell replacement therapy. In this review, recent development in stem cell treatment for PD, using hiPSCs, as well as the potential value of hiPSCs in modelling for PD, have been summarized for application of iPSCs technology to clinical translation for PD treatment.

Carbidopa/Levodopa ER Capsules (Rytary(®), Numient™): A Review in Parkinson's Disease

A new extended-release (ER) capsule formulation of carbidopa/levodopa (Rytary(®), Numient™, IPX066) is available for the treatment of Parkinson's disease (PD). Carbidopa/levodopa ER capsules contain beads of carbidopa and levodopa, designed to release the drugs at different rates in the gastrointestinal tract and provide constant therapeutic levodopa concentrations that are maintained for 4-5 h (after an initial peak at ≈ 1 h). In randomized phase III trials, oral carbidopa/levodopa ER was significantly more effective than placebo with regard to improving motor symptoms and activities of daily living in patients with early PD after 30 weeks' treatment, and provided significantly greater reductions in daily 'off-time' in patients with advanced PD than immediate-release (IR) carbidopa/levodopa or carbidopa/levodopa IR plus entacapone after a treatment period of 13 and 2 weeks, respectively, without increasing troublesome dyskinesia. The efficacy of carbidopa/levodopa ER was maintained during a 9-month open-label extension in patients with early or advanced PD. Carbidopa/levodopa ER was generally well tolerated in clinical trials, with the most common adverse events in the extension study being nausea and insomnia in patients with early PD and falls and dyskinesia in patients with advanced PD. Thus, carbidopa/levodopa ER is an effective and generally well-tolerated treatment option for the motor symptoms of PD, reducing periods of 'off-time' compared with carbidopa/levodopa IR without increasing troublesome dyskinesia.

G-Force PD: a global initiative in coordinating stem cell-based dopamine treatments for Parkinson's disease

Translating new cell-based therapies to the clinic for patients with neurodegenerative disorders is complex. It involves pre-clinical testing of the cellular product and discussions with several regulatory agencies, as well as ethical debates. In an attempt to support efforts around the world, we set up a global consortium that brings together the major funded teams working on developing a stem cell-derived neural transplantation therapy for Parkinson's disease (PD). This consortium, G-Force PD, involves teams from Europe, USA, and Japan, and has already met on two occasions to discuss common problems, solutions, and the roadmap to the clinic. In this short review, we lay out the brief history and rationale for this initiative and discuss some of the issues that arose in our most recent meeting (May 2015) as we consider undertaking first-in-human clinical trials with stem cell-derived neurons for PD.

Dyskinesias and impulse control disorders in Parkinson's disease: From pathogenesis to potential therapeutic approaches

Dopaminergic treatment in Parkinson's disease (PD) reduces the severity of motor symptoms of the disease. However, its chronic use is associated with disabling motor and behavioral side effects, among which levodopa-induced dyskinesias (LID) and impulse control disorders (ICD) are the most common. The underlying mechanisms and pathological substrate of these dopaminergic complications are not fully understood. Recently, the refinement of imaging techniques and the study of the genetics and molecular bases of LID and ICD indicate that, although different, they could share some features. In addition, animal models of parkinsonism with LID have provided important knowledge about mechanisms underlying such complications. In contrast, animal models of parkinsonism and abnormal impulsivity, although useful regarding some aspects of human ICD, do not fully resemble the clinical phenotype of ICD in patients with PD, and until now have provided limited information. Studies on animal models of addiction could complement the previous models and provide some insights into the background of these behavioral complications given that ICD are regarded as behavioral addictions. Here we review the most relevant advances in relation to imaging, genetics, biochemistry and pharmacological interventions to treat LID and ICD in patients with PD and in animal models with a view to better understand the overlapping and unique maladaptations to dopaminergic therapy that are associated with LID and ICD.