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Levodopa treatment remains the gold standard for Parkinson's disease, but shortcomings related to the pharmacological profile, notably, oral administration and the consequent occurrence of motor complications, have led to the development of several add-on levodopa treatments or to research to improve the method of delivery. Motor fluctuations, and to a lesser extent non-motor fluctuations, concern half of the patients with Parkinson's disease after 5 years of disease and patients identified them as one of their most bothersome symptoms. Catechol-O-methyl transferase inhibitors (COMT-Is) are one of the recommended first-line levodopa add-on therapies for the amelioration of end-of dose motor fluctuations in patient with advanced Parkinson's disease. Currently, two peripheral COMT-Is are considered as first-line choices - entacapone (ENT), which was approved by the US Food and Drug Administration in 1999 and the European Committee in 1998; and opicapone (OPC), which was approved by the European Committee in 2016. A second-line COMT-I that requires regular hepatic monitoring, tolcapone (TOL), was approved by the Food and Drug Administration in 1998 and the European Committee in 1997. Of note, OPC also received Food and Drug Administration approval in 2021, but it is still only marketed in a few countries, including Germany, UK, Spain, Portugal, Italy, Japan, and USA, while ENT and TOL have a wider market. Our narrative review summarizes the pharmacokinetic/pharmacodynamic properties, clinical efficacy in terms of motor fluctuations, motor/non-motor symptoms, quality of life, and safety data of these three COMT-Is, as evidenced by randomized clinical trials, as well as by real-life observational studies. Overall, a phase III non-inferiority trial showed a similar effect between ENT and OPC on off-time (−60.8 min/day and −40.3 min/day, vs placebo, respectively), with a possible additional off-time reduction of 39 min/day, obtained when there is a switch from ENT to OPC. Concomitantly, TOL can reduce off-time by an average of 98 min/day. A significant though discrete concomitant reduction on the Unified Parkinson's Disease Rating Scale motor section (2–3 points) is obtained with all three drugs vs placebo. Data on quality of life are fewer and more heterogeneous, with positive results obtained especially in open-label studies. Effects on non-motor symptoms were investigated as secondary outcome only in a few studies, frequently by means of non-specific scales and a benefit was observed in open-label studies. Dopaminergic adverse effects were the most frequent, dyskinesia being the most common for the three drugs eventually requiring levodopa dose reductions. No urine discoloration and a very low incidence of diarrhea were found with OPC compared with ENT and TOL. Regular hepatic monitoring is needed only for TOL. A combination of COMT-Is with new formulations of levodopa, including the subcutaneous, intrajejunal, or new extended-release formulation, merits further exploration to improve the management of both mild and severe motor fluctuations. [ABSTRACT FROM AUTHOR]

Background: A global overview of drug development programs in Parkinson's disease over the last few decades is lacking, while such programs are challenging given the multifaceted and heterogeneous nature of the disease. Objective: To indirectly assess drug development programs in Parkinson's disease, exploring some factors associated with compound attrition at different trial phases. Methods: We assessed all Parkinson's disease trials in the WHO trials portal, from inception (1999) to September 2019. Independent authors selected trials and extracted data. The success rate was the number of compounds that progressed to the next drug development phase divided by the number of compounds in that phase. Results: Overall, 357 trials (studying 152 compounds) fulfilled our inclusion criteria, with 62 (17.3%) phase 1 trials, 135 (37.8%) phase 2 trials, 85 (23.8%) phase 3 trials, and 53 (14.8%) phase 4 trials. The success rate was 42.4% from phase 2 to 3. Original compounds received regulatory approval by the FDA in 21.4% of cases, compared with 6.7% of repurposed compounds, representing an overall success rate of 14.9%. We found 172 trials (48.2%) conducted for repurposing previously licensed compounds. These figures were approximately the same regarding approval by the EMA. Most compounds were approved to treat parkinsonism and motor fluctuations. Conclusion: We found a moderate-to-high success rate in all phases of drug development. This was largely based on the success of original compounds, despite almost half of the identified trials attempting compound repurposing. [ABSTRACT FROM AUTHOR]

Background: Opicapone is a catechol O-methyltransferase (COMT) inhibitor indicated for use as adjunct to levodopa therapy in patients with Parkinson's disease (PD) and motor fluctuations. Objective: To characterize the safety and tolerability of adjunct opicapone (25 and 50 mg) in a pooled population of levodopa-treated PD patients who participated in the opicapone Phase-3 clinical program. Methods: Patient-level data (placebo, opicapone 25 mg and 50 mg) from the BIPARK-1 and BIPARK-2 double-blind and open-label studies were combined. Results: Pooled analyses included 766 patients from the double-blind studies and 848 patients from the open-label studies. In the double-blind studies, 63.3% of opicapone-treated patients reported treatment-emergent adverse events (TEAEs) versus 57.2% in the placebo group. The most common TEAEs reported in the opicapone group compared to placebo were dyskinesia, constipation and insomnia. The incidence of serious TEAEs was similar across opicapone and placebo groups (3.5% versus 4.3%, respectively). Overall, 71.3% patients treated with open-label opicapone reported at least one TEAE; most occurred within the first 2 months of the open-label studies, and then decreased thereafter. Throughout the Phase-3 clinical program, there were no serious AEs suggestive of hepatic toxicity, and the incidence of gastrointestinal disorders such as nausea and diarrhea remained low (<2%). There were no relevant changes in laboratory parameters including liver enzymes, vital signs, physical or neurological examinations, or ECG readings. Conclusions: Long-term use of opicapone once-daily over 1-year at doses of 25 mg or 50 mg was generally safe and well tolerated, supporting its clinical usefulness in the management of PD motor fluctuations. [ABSTRACT FROM AUTHOR]

Background: Essential tremor is one of the most prevalent movement disorders. Many treatments for essential tremor have been reported in clinical practice, but it is uncertain which options have the most robust evidence. The International Parkinson and Movement Disorder Society commissioned a task force on tremor to review clinical studies of treatments for essential tremor.Objectives: To conduct an evidence-based review of current pharmacological and surgical treatments for essential tremor, using standardized criteria defined a priori by the International Parkinson and Movement Disorder Society.Methods: We followed the recommendations of the International Parkinson and Movement Disorder Society Evidence Based Medicine Committee.Results: Sixty-four studies of pharmacological and surgical interventions were included in the review. Propranolol and primidone were classified as clinically useful, similar to Topiramate, but only for doses higher than 200 mg/day. Alprazolam and botulinum toxin type A were classified as possibly useful. Unilateral Ventralis intermedius thalamic DBS, radiofrequency thalamotomy, and MRI-guided focused ultrasound thalamotomy were considered possibly useful. All the above recommendations were made for limb tremor in essential tremor. There was insufficient evidence for voice and head tremor as well as for the remaining interventions.Conclusion: Propranolol, primidone, and topiramate (>200 mg/day) are the pharmacological interventions in which the data reviewed robustly supported efficacy. Their safety profile and patient preference may guide the prioritization of these interventions in clinical practice. MRI-guided focused ultrasound thalamotomy was, for the first time, assessed and was considered to be possibly useful. There is a need to improve study design in essential tremor and overcome the limitation of small sample sizes, cross-over studies, short-term follow-up studies, and use of nonvalidated clinical scales. © 2019 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

In this edition of the Huntington's Disease Clinical Trials Corner we expand on the HD-DBS and on the TRIHEP3 trials, and we list all currently registered and ongoing clinical trials in Huntington's disease. [ABSTRACT FROM AUTHOR]

Introduction: Ibrutinib is an oral covalent inhibitor of Bruton's tyrosine kinase approved for the treatment of patients with chronic lymphocytic leukemia (CLL), mantle cell lymphoma and Waldenstrӧm’s macroglobulinemia. Ibrutinib has an increased risk of atrial fibrillation but the mechanism is unknown, and hypertension may play a role in the pathogenesis of this adverse drug reaction. Methods: We aimed to review the risk of hypertension and atrial fibrillation as adverse events associated with ibrutinib through a systematic review with meta-analysis of randomized controlled trials (RCTs) retrieved in December 2018 on MEDLINE, EMBASE, CENTRAL and ClinicalTrials.gov. The data were pooled using random-effects meta-analyses using the risk ratio (RR) with the 95% confidence interval (95%CI). The confidence on the pooled estimates was ascertained through the grading of recommendations assessment, development, and evaluation (GRADE) approach. Results: There were 8 eligible RCTs (2580 patients), all reporting safety data of interest. Ibrutinib was associated with a significant increase in the risk of hypertension with a RR of 2.82 (95%CI 1.52–5.23) with moderate quality evidence. Ibrutinib increased significantly the risk of atrial fibrillation with a RR of 4.69 (95%CI 2.17–7.64) with high quality evidence. Conclusions: Ibrutinib was associated with significantly increased risks of both hypertension and atrial fibrillation. [ABSTRACT FROM AUTHOR]

Multiple system atrophy (MSA) is a rare neurodegenerative disease of undetermined cause. Although many clinical trials have been conducted, there is still no treatment that cures the disease or slows its progression. We sought to assess the clinical trials, methodology, and quality of reporting of clinical trails conducted in MSA patients. We conducted a systematic review of all trials with at least 1 MSA patient subject to any pharmacological/nonpharmacological interventions. Two independent reviewers evaluated the methodological characteristics and quality of reporting of trials. A total of 60 clinical trials were identified, including 1375 MSA patients. Of the trials, 51% (n = 31) were single-arm studies. A total of 28% (n = 17) had a parallel design, half of which (n = 13) were placebo controlled. Of the studies, 8 (13.3%) were conducted in a multicenter setting, 3 of which were responsible for 49.3% (n = 678) of the total included MSA patients. The description of primary outcomes was unclear in 60% (n = 40) of trials. Only 10 (16.7%) clinical trials clearly described the randomization process. Blinding of the participants, personnel, and outcome assessments were at high risk of bias in the majority of studies. The number of dropouts/withdrawals was high (n = 326, 23.4% among the included patients). Overall, the design and quality of reporting of the reviewed studies is unsatisfactory. The most frequent clinical trials were small and single centered. Inadequate reporting was related to the information on the randomization process, sequence generation, allocation concealment, blinding of participants, and sample size calculations. Although improved during the recent years, methodological quality and trial design need to be optimized to generate more informative results. © 2017 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Background In a rare disorder such as Huntington's disease ( HD), a global network of clinical trial sites with access to patients speeds up recruitment into clinical trials. The objective was to test the hypothesis that demographics, HTT genotype, clinical spectrum, and progression are similar in HD participants of two large observational HD studies, the European Huntington's Disease Network's European REGISTRY study and the North American COHORT study. Methods REGISTRY cross-sectional data were available from a total of 7,384 participants (1,125 [15.2%] premanifest and 6,259 [84.8%] manifest HD). COHORT cross-sectional data from 1,499 participants at 44 study sites were available (175 pre- HD [11.7%], 1,324 manifest HD [88.3%]). Participants were assessed clinically using the Unified Huntington's Disease Rating Scale ( UHDRS). Longitudinal data were available for total motor score and cognitive performance in more than 50% of REGISTRY participants and more than 70% of COHORT participants. Results Demographics, HTT genotypes, phenotype, and progression were similar in the two studies. Patients in Europe were prescribed antidyskinetics more frequently, and antidepressants less frequently, than in North America. In either study, participants on antidyskinetic medication had higher UHDRS total motor scores, worse function assessment scores, and worse cognitive scores than those taking antidepressants or no medication. In contrast, motor, function assessment, and cognitive scores were broadly similar in participants taking antidepressants or no medication. The differences in cognitive performances between languages were small. Conclusions Our data suggest that HD patients, and the way they are assessed, are similar across two continents with different cultures and languages. [ABSTRACT FROM AUTHOR]

Background: Drug development in Huntington's disease (HD) is particularly challenging, and only two compounds are approved by the FDA. It is therefore essential to appraise drug development programs in order to understand the reasons for their failure during the early stages of development. Objectives: To describe the landscape of HD therapeutic development and critically explore the causes of compound attrition in the different stages of drug development, from phase 1 to phase 4. Methods: All HD clinical trials registered in the WHO International Clinical Trials Search Portal, from inception to May 2017, were analyzed. Two independent authors selected and extracted data. Success rate in a trial phase was calculated as the number of compounds that progressed to the next trial phase divided by the number of compounds in that phase. The overall success rate was calculated as the ratio between the number of compounds that receive regulatory approval and the total number of compounds. Results: Ninety-nine trials assessing 41 compounds and eleven non-pharmacological interventions (devices and cell therapies) were identified. Twenty-four (24.2%) were phase 1 trials, 46 (46.5%) phase 2, 20 (20.2%) phase 3, and two (2.0%) phase 4. Sixty trials (60.6%) received industry sponsorship. The most frequently studied compounds were creatine, latrepirdine and pridopidine. The mean number of participants enrolled was 92.0 and the length of treatment was 262.9 days, and both increased from phase 1 to phase 3 trials. The success rate was 25.0% from phase 1 to phase 2, 19.4% from phase 2 to phase 3, and 14.3% from phase 3 to approval. The overall success rate was 3.5%. Conclusions: Although HD is a rare condition, 99 HD trials were identified in a comprehensive clinical trial registry. We found a low success rate at earlier phases of drug-development and a very low trial success rate at later phases. There is a significant gap between drug discovery and development success rates that warrants careful appraisal and improvement. [ABSTRACT FROM AUTHOR]

Background: Over the past decades there has been a significant increase in the number of published clinical trials in palliative care. However, empirical evidence suggests that there are methodological problems in the design and conduct of studies, which raises questions about the validity and generalisability of the results and of the strength of the available evidence. We sought to evaluate the methodological characteristics and assess the quality of reporting of clinical trials in palliative care. Methods: We performed a systematic review of published clinical trials assessing therapeutic interventions in palliative care. Trials were identified using MEDLINE (from its inception to February 2015). We assessed methodological characteristics and describe the quality of reporting using the Cochrane Risk of Bias tool. Results: We retrieved 107 studies. The most common medical field studied was oncology, and 43.9% of trials evaluated pharmacological interventions. Symptom control and physical dimensions (e.g. intervention on pain, breathlessness, nausea) were the palliative care-specific issues most studied. We found under-reporting of key information in particular on random sequence generation, allocation concealment, and blinding. Conclusions: While the number of clinical trials in palliative care has increased over time, methodological quality remains suboptimal. This compromises the quality of studies. Therefore, a greater effort is needed to enable the appropriate performance of future studies and increase the robustness of evidence-based medicine in this important field. [ABSTRACT FROM AUTHOR]

Background: There is increasing evidence to suggest a tight relationship between cognitive impairment and falls in Parkinson's disease (PD). Here, we draw attention to a potentially significant flaw in the existent falls-related research, namely the apparent exclusion of patients with cognitive impairment or dementia. Objective: Our objective was to review all published, on-going or scheduled fall-related intervention studies, in order to investigate the extent to which cognitively impaired individuals with PD were included in these studies. Methods: We analyzed published controlled trials regarding falls and PD in commonly used databases, as well as relevant ongoing clinical trials registered within the World Health Organization database, clinicaltrials.gov and the European Clinical Trials Database. Results: Fourteen of the fifteen published studies included had explicit cognitive exclusion criteria as part of their study protocol. Most of the 54 on-going PD fall-related studies excluded patients with cognitive impairment. Conclusions: This suggests that individuals with cognitive impairment or dementia are excluded from fall-related research studies. We strongly recommend that future work in this area should include a representative sample of patients with PD, including subjects with cognitive decline. [ABSTRACT FROM AUTHOR]

To determine the efficacy, safety and tolerability of nebicapone, a new catechol- O-methyltransferase inhibitor for the treatment of motor fluctuations in Parkinson's disease (PD), we conducted a multicenter, randomized, 8-week double-blind, placebo- and active-controlled, parallel-group study comparing nebicapone 50 mg, 100 mg, or 150 mg, entacapone 200 mg (active control) or placebo administered concomitantly with levodopa/carbidopa or levodopa/benserazide. Two hundred and fifty-two PD patients with motor fluctuations treated with levodopa/carbidopa or levodopa/benserazide (4-8 daily doses) were enrolled and 250 patients were eligible for intention-to-treat (ITT) analysis on the basis of having at least one efficacy assessment. The primary endpoint was 8-week change from baseline in absolute 'Off' time duration noted in self-scoring diaries. At 8 weeks of treatment the mean daily 'Off' time decreased significantly compared to placebo for nebicapone 150 mg (−106 min; 95%CI: −192; −21) and entacapone 200 mg (−81 min; 95%CI: −142; −19). The decrease in 'Off' time with nebicapone 50 mg or 100 mg did not reach statistical significance. Treatment-emergent adverse events were reported by 32% to 49% of patients in any treatment group, with no observed dose relationship in the nebicapone groups. Clinically relevant elevations in aspartate transaminase (AST) and/or alanine transaminase (ALT) were observed in 4 of 46 patients with the nebicapone 150 mg dose. The results of this study show that nebicapone 150 mg is efficacious for the treatment of motor fluctuations in PD patients. However, the risk of increasing liver transaminases and its clinically relevance deserves further evaluation. [ABSTRACT FROM AUTHOR]

This paper is a narrative review of the concept of evidence-based medicine (EBM) and its application in the movement disorders field. The paper has three parts:

The article present the results of ADAGIO trial which is intended to test whether the monoamine oxidase type B (MAO-B) inhibitor can be used as a medication for Parkinson's disease (PD). The study involved 1,176 patients with early, untreated PD who were randomly assigned to 72 weeks of rasagiline. For the trial to be successful, three hierarchical conditions should be met. It was found out that there is a significant delay in the progression of the disease.

Background: Daytime sleepiness and sleep disorders are frequently reported in Parkinson's disease (PD). However, their impact on quality of life has been underestimated and few clinical trials have been performed.Objectives: We aimed to assess the efficacy and safety of pharmacological interventions for daytime sleepiness and sleep disorders in PD.Methods: Systematic review of randomized controlled trials comparing any pharmacological intervention with no intervention or placebo for the treatment of daytime sleepiness and sleep problems in PD patients.Results: Ten studies (n = 338 patients) were included. Four trials addressed interventions for excessive daytime sleepiness. Meta-analysis of the three trials evaluating modafinil showed a significant reduction in sleepiness, as assessed by the Epworth Sleepiness Scale (ESS) (- 2.24 points, 95% CI - 3.90 to - 0.57, p < 0.05). In one study, treatment with caffeine was associated with a non-significant improvement of 1.71 points in ESS (95% CI, - 3.57 to 0.13). The six remaining trials assessed interventions for insomnia and REM sleep Behaviour Disorder (RBD). Single study results suggest that doxepin and YXQN granules might be efficacious, while pergolide may be deleterious for insomnia and that rivastigmine may be used to treat RBD in PD patients. However, there is insufficient evidence to support or refute the efficacy of any of these interventions. No relevant side effects were reported.Conclusions: Whilst providing recommendations, this systematic review depicts the lack of a body of evidence regarding the treatment of sleep disorders in PD patients; hence, further studies are warranted. [ABSTRACT FROM AUTHOR]

Background: Exercise therapy is becoming extremely relevant as a new efficacious intervention in multiple medical fields. Although several clinical trials have reported benefits of exercise therapy for Parkinson's disease (PD), recommendations and prescriptions for its use in clinical practice remain limited.Objectives: To evaluate the methodological quality and publication rate of clinical trials on exercise therapy for PD.Methods: We analyzed all clinical trials assessing exercise therapy for PD registered in the WHO International Clinical Trials Registry Platform and the ClinicalTrials.gov registries, from 2000 to 2017. We evaluated the methodological quality of trials using the Cochrane Risk of Bias criteria.Results: A total of 236 clinical trials were identified. Only 70 (29.7%) trials reported their findings, and 61 (25.8%) had results published in scientific journals. Most trials had an unclear risk of bias concerning incomplete and selective outcome reporting and lacked data on the randomization process, allocation concealment, blinding of participants and personnel, and outcomes assessors. Aerobic capacity was the most frequent type of exercise intervention.Conclusions: Although a large number of trials on exercise are registered in international portals, the quality of reporting remains suboptimal and only a quarter of trials have their results published in scientific journals. These two factors, in addition to the heterogeneity of the interventions tested and the unsatisfactory reported methodological quality of most trials, compromise the interpretation of study results. Therefore, higher quality clinical trials reports are needed to establish exercise as part of the PD armamentarium. [ABSTRACT FROM AUTHOR]

Objective: To estimate the magnitude of the nocebo response in Parkinson's disease and explore possible associations with study characteristics.Methods: Databases were searched up to February 2017. Placebo-controlled, parallel-group randomized controlled trials investigating pharmacological interventions in people with Parkinson's disease were included. Data were derived from the last measured within-group response in the placebo and intervention arms of randomized controlled trials, after independent extraction. A random-effects model was used to pool study data. The main outcome was the nocebo response, measured as the proportion of placebo-treated participants experiencing any adverse events (AEs). We also measured the proportion of patients with serious AEs (SAEs), and the rates of study dropouts (including due to AEs) and death. PROSPERO registration number is CRD42017070471.Results: We included 236 randomized controlled trials, with a combined population of 17,381 participants allocated to placebo. The nocebo response was 56.0% (95% CI, 51.7%-60.4%; 148 trials; I2 = 98%). SAEs were reported in 4.0% (95% CI, 3.4%-4.6%, 157 trials; I2 = 73%) of placebo-treated patients, dropouts in 14.0% (95% CI, 12.5%-15.5%, 225 trials; I2 = 91%), dropouts due to AEs in 5.7% (95% CI, 5.1%-6.4%, 219 trials; I2 = 73%). Deaths occurred in 0.6% (95% CI, 0.5%-0.7%, 227 trials; I2 = 0%). Similar proportions were identified in patients in intervention arms.Conclusions: The magnitude of the nocebo response in parallel-designed randomized controlled trials in Parkinson's disease is substantial and should be considered in the interpretation of safety results and in the design and interpretation of future clinical trials. [ABSTRACT FROM AUTHOR]

Abstract: Reluctance to start medication has never been investigated before in PD. We studied reluctance to start medication for PD motor symptoms, namely its prevalence, underlying reasons, drug-specificity, and associated delay in the start of PD medication. A cross-sectional observational international study was conducted. Patients with a clinical diagnosis of PD advised to start antiparkinsonian medication in the previous 5 years were invited to complete a questionnaire in three centers located in North America and Europe. An electronic online survey was sent to physicians through the mailing list of the Movement Disorder Society. 469 participants (201 PD patients, 268 physicians). 40.2% (n = 82) of the patients reported reluctance to start medication, but 88.6% (n = 234/264) of the physicians estimated that ≤20% of their patients with PD had been reluctant to start medication. The most common reasons reported by patients were the fear of side effects (n = 35, 55.6%), followed by non-acceptance of diagnosis (n = 23, 36.5%); fear of a temporally limited benefit was more commonly selected by physicians (n = 92/267, 34.5%). Patients indicated reluctance to start DAs more frequently compared with L-DOPA (OR: 2.22, 95% CI: 1.30, 9.03; p = 0.013) while physicians perceived L-DOPA to be associated with more reluctance (OR: 4.7, 95% CI: 3.41; 6.59; p < 0.0001). Patients with PD and physicians have a different perspective on the issue of reluctance to start medication. There is a need to bring physicians and patients with PD closer to a shared vision of the problem reluctance to start medication. [Copyright &y& Elsevier]

Abstract: Introduction: Limited data is available regarding motivations and concerns of Parkinson’s disease (PD) patients when participating in clinical trials (CTs). Knowledge of these factors may improve the recruitment and quality of future trials. Objectives: To assess the motivations and concerns of PD patients concerning participation in CTs and to evaluate the extent to which patients understand informed consent materials and placebo effect concept. Methods: Cross-sectional study in PD patients enrolled in CTs between 2002 and 2007. Two questionnaires designed for placebo-controlled and active-controlled studies were mailed to patients. Results: From the 93/127 replied questionnaires (response rate: 73.2%) 91 were evaluable. Fifty-nine percent of the participants were women with a mean age of 66.8 years. The main reasons for participating in CTs were to help the advance of science (63.7%), to gain access to a better treatment (56.0%), and to benefit others (51.6%). Risk of adverse events (49.5%) and negative effects of treatment (35.2%) were the major concerns. Ninety percent reported they had understood the informed consent. Of 80 patients included in placebo-controlled studies, 63.9% understood the placebo effect concept. Globally, 66% of patients would participate in another CT and 41.6% in a placebo-controlled trial. Conclusions: The main motivations of PD patients to participate in CTs were the benefit to the patient himself and to others. The major concern was safety. PD patients understood the informed consent, but more educational efforts must be made to explain the placebo effect. Most PD patients were very positive toward CTs and would participate in another trial. [Copyright &y& Elsevier]