Safety and efficacy of continuous subcutaneous foslevodopa-foscarbidopa in patients with advanced Parkinson's disease: a randomised, double-blind, active-controlled, phase 3 trial.

BACKGROUND: Levodopa is the most effective symptomatic therapy for Parkinson's disease, but patients with advanced Parkinson's disease develop motor fluctuations with chronic oral levodopa therapy. Foslevodopa-foscarbidopa is a soluble formulation of levodopa and carbidopa prodrugs that is delivered as a 24-h/day continuous subcutaneous infusion, and we aimed to assess the safety and efficacy of this formulation in patients with advanced Parkinson's disease. METHODS: A 12-week randomised, double-blind, double-dummy, active-controlled study was done at 65 academic and community study centres in the USA and Australia. Patients with levodopa-responsive advanced Parkinson's disease inadequately controlled on current therapy, including at least 2·5 h of average daily off time, were randomly assigned (1:1) to continuous subcutaneous infusion of foslevodopa-foscarbidopa plus oral placebo or to oral immediate-release levodopa-carbidopa plus continuous subcutaneous infusion of placebo solution. Randomisation was stratified by site by means of a permutated-block schedule with a block size of two. The participants, treating investigators, study site personnel, and sponsor were masked to treatment group allocation. The primary and first key secondary endpoint in the hierarchical testing strategy were change from baseline to week 12 in on time without troublesome dyskinesia and off time, respectively; both endpoints were evaluated by an intention-to-treat analysis applying a mixed model for repeated measures analysis. Safety and tolerability were assessed throughout the study. The study is completed and is listed on ClinicalTrials.gov, NCT04380142. FINDINGS: Between Oct 19, 2020, and Sept 29, 2021, of 270 participants screened and 174 enrolled, 141 were randomly assigned and received continuous subcutaneous infusion of foslevodopa-foscarbidopa plus oral placebo capsules (n=74) or oral encapsulated immediate-release levodopa-carbidopa plus continuous subcutaneous infusion of placebo solution (n=67). Compared with levodopa-carbidopa, foslevodopa-foscarbidopa showed a significantly greater increase in on time without troublesome dyskinesia (model-based mean [SE] 2·72 [0·52] vs 0·97 [0·50] h; difference 1·75 h, 95% CI 0·46 to 3·05; p=0·0083) and a significantly greater reduction in off time (-2·75 [0·50] vs -0·96 [0·49] h; difference -1·79 h, -3·03 to -0·54; p=0·0054). Hierarchical testing ended after the first secondary endpoint. Adverse events were reported in 63 (85%) of 74 patients in the foslevodopa-foscarbidopa group versus 42 (63%) of 67 in the levodopa-carbidopa group, and incidences of serious adverse events were similar between the groups (six [8%] of 74 vs four [6%] of 67, respectively). The most frequent adverse events in the foslevodopa-foscarbidopa group were infusion site adverse events (erythema 20 [27%]), pain 19 [26%]), cellulitis (14 [19%]), and oedema (nine [12%]), most of which were non-serious and mild-moderate in severity. The only system organ class that had more than one serious adverse event in the foslevodopa-foscarbidopa group was infections and infestations (catheter site cellulitis [one [1%]] and infusion site cellulitis [one [1%]). Adverse events led to premature discontinuation of study drug in 16 (22%) of 74 participants in the foslevodopa-foscarbidopa group versus one (1%) of 67 participants in the oral levodopa-carbidopa group. INTERPRETATION: Foslevodopa-foscarbidopa improved motor fluctuations, with benefits in both on time without troublesome dyskinesia and off time. Foslevodopa-foscarbidopa has a favourable benefit-risk profile and represents a potential non-surgical alternative for patients with advanced Parkinson's disease. FUNDING: AbbVie.

An approach to acute clinical deterioration in patients with late-stage Parkinson's disease.

BACKGROUND: Idiopathic Parkinson's disease is a slowly progressive neurodegenerative disease. In the absence of disease-modifying therapies, patients inevitably progress to late-stage disease, characterised by a shift towards increasing disability from predominantly non-motor symptoms, which may be poorly levodopa responsive. OBJECTIVE: The aim of this article is to provide general practitioners (GPs) with a practical approach to the diagnosis and management of acute clinical deterioration in patients with late-stage Parkinson's disease. The authors outline common causes for such change and an approach to their workup and management. DISCUSSION: With an ageing population, we are seeing an increased prevalence of Parkinson's disease at all stages. Neurologists, geriatricians and GPs alike should therefore be familiar with the syndrome of late-stage Parkinson's disease and be equipped with treatment strategies to address acute non-motor and motor deteriorations.

The initial diagnosis and management of Parkinson's disease.

BACKGROUND: Parkinson's disease is a common, progressive neurodegenerative disorder, the prevalence of which is on the rise. The diagnosis and management of Parkinson's disease is therefore likely to become increasingly frequent in general practice. OBJECTIVE: The aim of this article is to provide a practical overview for the general practitioner of the initial diagnosis and management of Parkinson's disease. DISCUSSION: Parkinson's disease is a multisystem disorder, and the way the diagnosis is delivered, as well as the early management, can have a lasting impact on the patient experience. In this article, the authors present their preferred approach to diagnosis and initial treatment, while highlighting common pitfalls and some useful simple strategies for communicating the diagnosis.

Rest tremor correlates with reduced contralateral striatal dopamine transporter binding in Parkinson's disease.

INTRODUCTION: In vivo dopamine transporter imaging is a useful tool for distinguishing nigrostriatal pathologies (e.g. Parkinson's disease) from other causes of tremor. However, while many of the motoric features of Parkinson's disease (e.g. bradykinesia, rigidity, hypomimia) correlate well with reduced striatal dopamine transporter binding, the same relationship has not been demonstrated for tremor. We investigated the relationship between striatal dopamine transporter binding and quantitative measures of tremor. METHODS: 23 participants with Parkinson's disease underwent standardised clinical assessment including structured, videotaped clinical examination, tremor neurophysiology study of both upper limbs using accelerometry and surface EMG, and Technitium-99 m TRODAT-1 brain SPECT imaging. Normalised striatal uptake values were calculated. Tremor EMG and accelerometry time series were processed with Fourier transformation to identify peak tremor power within a window of 3-10Hz and to calculate the tremor stability index (TSI). RESULTS: Spearman correlation analyses revealed an association between tremor power and contralaterally reduced striatal uptake in a number of recording conditions. This association was strongest for rest tremor, followed by postural tremor, with the weakest association observed for kinetic tremor. Lower TSI was also associated with lower contralateral striatal uptake in a number of rest and postural conditions. CONCLUSION: These data suggest a relationship between Parkinsonian rest tremor and contralateral reduction in striatal dopamine binding. Use of quantitative neurophysiology techniques may allow the demonstration of clinico-pathophysiological relationships in tremor that have remained occult to previous studies.

Updates and advances in the treatment of Parkinson disease.

Parkinson disease (PD) is a complex neurodegenerative disorder that can present heterogeneously with a combination of motor and non-motor symptoms. α-synuclein, a neuronal protein, can undergo aberrant conformational change resulting in the intra-neuronal accumulation of toxic oligomers that form Lewy bodies, the pathological hallmark of PD. There is evidence that pathological α-synuclein exhibits prion-like behaviour in its mode of transmission through the nervous system. The choice of initial dopaminergic treatments should be individually tailored but long term outcomes appear to be equivalent. There is level A evidence supporting the benefit of three different device-assisted therapies in treating troublesome motor fluctuations and dyskinesias. Stem cell transplantation as currently being trialled is predominantly a symptomatic therapy targeting only limited regions of the brain affected by PD, and will need to be proven to be not only as effective but as safe as currently available device-assisted therapies. New modes of treatment including active immunisation against oligomeric α-synuclein and drugs that alter cellular metabolism show some promise. The inability to effectively treat a range of non-motor, non-dopaminergic symptoms remains a major therapeutic challenge.

Clinical significance of pharmacogenomic studies in tardive dyskinesia associated with patients with psychiatric disorders.

Pharmacogenomics is the study of the effects of genetic polymorphisms on medication pharmacokinetics and pharmacodynamics. It offers advantages in predicting drug efficacy and/or toxicity and has already changed clinical practice in many fields of medicine. Tardive dyskinesia (TD) is a movement disorder that rarely remits and poses significant social stigma and physical discomfort for the patient. Pharmacokinetic studies show an association between cytochrome P450 enzyme-determined poor metabolizer status and elevated serum antipsychotic and metabolite levels. However, few prospective studies have shown this to correlate with the occurrence of TD. Many retrospective, case-control and cross-sectional studies have examined the association of cytochrome P450 enzyme, dopamine (receptor, metabolizer and transporter), serotonin (receptor and transporter), and oxidative stress enzyme gene polymorphisms with the occurrence and severity of TD. These studies have produced conflicting and confusing results secondary to heterogeneous inclusion criteria and other patient characteristics that also act as confounding factors. This paper aims to review and summarize the pharmacogenetic findings in antipsychotic-associated TD and assess its clinical significance for psychiatry patients. In addition, we hope to provide insight into areas that need further research.

Active exercise for individuals with cervical dystonia: a pilot randomized controlled trial.

OBJECTIVE: To investigate the feasibility and effectiveness of an active exercise program for cervical dystonia. DESIGN: Pilot randomized controlled, single-blind trial of a 12-week intervention followed by a four-week follow-up period. SETTING: Supervised physiotherapy and outcome measurement sessions were conducted in a hospital outpatient physiotherapy setting. Participants also performed exercises at home. SUBJECTS: Twenty participants with idiopathic cervical dystonia were randomized into an experimental (n = 9) or control (n = 11) group. Two participants from the experimental group and one from the control group dropped out. INTERVENTIONS: The experimental group undertook a semi-supervised active exercise program aimed at correcting the dystonic head position, plus relaxation. The control group performed relaxation only. MAIN OUTCOME MEASURES: Feasibility of the intervention was assessed by recording adherence, muscle soreness, and adverse events. The primary outcome measure was blinded analysis of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) score. RESULTS: The active exercise program was feasible and safe, with participants in the experimental group completing 84% of prescribed training sessions in the 12-week intervention period. There were no adverse events in either group, while mild muscle soreness was reported by 66% of the experimental group. There was no significant difference between groups at post-test or follow-up. The difference between groups of -1.9 (95% confidence interval (CI) -9.0-5.2) on the TWSTRS demonstrates a trend towards greater improvement for the experimental group. CONCLUSION: Active exercise for people with cervical dystonia is feasible and can be completed with good adherence and no adverse effects.