Rasagiline adjunct therapy in patients with Parkinson's disease: post hoc analyses of the PRESTO and LARGO trials

The Role of MAO-B Inhibitors in Fatigue in Parkinson's Disease: A Narrative Review

Background: Fatigue is a common and debilitating non-motor symptom (NMS) in Parkinson's disease (PD), significantly affecting patients' quality of life. MAO-B inhibitors are effective therapy for motor symptoms and fluctuations and may also play a role in fatigue management. Methods: We searched PubMed for English-language articles (January 1978-August 2024) using keywords including "selegiline", "rasagiline", "safinamide", "MAO-B", "fatigue", and "Parkinson's disease". Clinical trials, observational, and preclinical studies were included. Results: While the role of MAO-B inhibitors in fatigue remains unclear, evidence suggests potential benefits. Selegiline has shown effectiveness in improving fatigue in animal models, supporting its potential utility in treating fatigue and motivational impairments in PD patients. Rasagiline has been associated with reduced fatigue progression in early PD, with some studies showing significant improvements compared to placebo. Safinamide, with its dual action as an MAO-B inhibitor and glutamate modulator, may further enhance fatigue management. Its ability to reduce glutamate release is particularly relevant, given the role of glutamate overactivity in PD-related fatigue. Studies indicate safinamide can significantly reduce fatigue levels. Conclusions: Fatigue in PD is a complex symptom with multiple contributing factors. While MAO-B inhibitors may support fatigue management, their precise role and optimal use require further investigation.

Sustained response in early responders to safinamide in patients with Parkinson's disease and motor fluctuations: A post hoc analysis of the SETTLE study

Safinamide is a selective, reversible, monoamine oxidase B inhibitor for the treatment of patients with Parkinson's disease (PD) and motor fluctuations. This was a post hoc analysis of the SETTLE study, in which patients with PD and motor fluctuations were randomly assigned to 24-week treatment with safinamide (50 mg/day for 2 weeks, increased to 100 mg/day if tolerated) or placebo. In the present analysis, responders were defined according to their treatment responses at Week 2 and Week 24 based on changes in ON-time without troublesome dyskinesia from baseline with cutoffs of 1 hour. It was found that 81% (103/127) of the responders at Week 2 maintained the response through Week 24 in the safinamide group. Other outcomes did not necessarily coincide with the ON-time response; however, “Early” responders who showed a treatment response at both Week 2 and Week 24 had substantial improvements from baseline in OFF-time, UPDRS Part II and III scores, and PDQ-39 summary index scores through Week 24. The safinamide group had a higher proportion of early responders than the placebo group (39% vs 20%, p < 0.0001). At baseline, early responders in the safinamide group had significantly higher UPDRS Part II and III scores, shorter ON-time, and longer OFF-time than the other responder populations. In conclusion, the results of the present post hoc analysis suggest that patients with a short ON-time, severe motor symptoms, and highly compromised activities of daily living can benefit from safinamide early in treatment and over the long term.

Monoamine-oxidase Type B Inhibitors and Cognitive Functions in Parkinson's Disease: Beyond the Primary Mechanism of Action

Symptoms of cognitive impairment are rather common since the early stage of Parkinson's disease (PD); they aggravate with disease progression and may lead to dementia in a significant proportion of cases. Worsening of cognitive symptoms in PD patients depends on the progression of subcortical dopaminergic damage as well as the involvement of other brain neurotransmitter systems in cortical and subcortical regions. Beyond the negative impact on disability and quality of life, the presence and severity of cognitive symptoms may limit adjustments of dopamine replacement therapy along the disease course. This review focuses on the consequences of the administration of monoamine-oxidase type Binhibitors (MAOB-I) on cognition in PD patients. Two drugs (selegiline and rasagiline) are available for the treatment of motor symptoms of PD as monotherapy or in combination with L-DOPA or dopamine agonists in stable and fluctuating patients; a further drug (safinamide) is usable in fluctuating subjects solely. The results of available studies indicate differential effects according to disease stage and drug features. In early, non-fluctuating patients, selegiline and rasagiline ameliorated prefrontal executive functions, similarly to other dopaminergic drugs. Benefit on some executive functions was maintained in more advanced, fluctuating patients, despite the tendency of worsening prefrontal inhibitory control activity. Interestingly, high-dose safinamide improved inhibitory control in fluctuating patients. The benefit of high-dose safinamide on prefrontal inhibitory control mechanisms may stem from its dual mechanism of action, allowing reduction of excessive glutamatergic transmission, in turn secondary to increased cortical dopaminergic input.

Neuroprotective Function of Rasagiline and Selegiline, Inhibitors of Type B Monoamine Oxidase, and Role of Monoamine Oxidases in Synucleinopathies

Synucleinopathies are a group of neurodegenerative disorders caused by the accumulation of toxic species of α-synuclein. The common clinical features are chronic progressive decline of motor, cognitive, behavioral, and autonomic functions. They include Parkinson’s disease, dementia with Lewy body, and multiple system atrophy. Their etiology has not been clarified and multiple pathogenic factors include oxidative stress, mitochondrial dysfunction, impaired protein degradation systems, and neuroinflammation. Current available therapy cannot prevent progressive neurodegeneration and “disease-modifying or neuroprotective” therapy has been proposed. This paper presents the molecular mechanisms of neuroprotection by the inhibitors of type B monoamine oxidase, rasagiline and selegiline. They prevent mitochondrial apoptosis, induce anti-apoptotic Bcl-2 protein family, and pro-survival brain- and glial cell line-derived neurotrophic factors. They also prevent toxic oligomerization and aggregation of α-synuclein. Monoamine oxidase is involved in neurodegeneration and neuroprotection, independently of the catalytic activity. Type A monoamine oxidases mediates rasagiline-activated signaling pathways to induce neuroprotective genes in neuronal cells. Multi-targeting propargylamine derivatives have been developed for therapy in various neurodegenerative diseases. Preclinical studies have presented neuroprotection of rasagiline and selegiline, but beneficial effects have been scarcely presented. Strategy to improve clinical trials is discussed to achieve disease-modification in synucleinopathies.

Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease: Past, Present, and Future

Monoamine oxidase-B (MAO-B) inhibitors are commonly used for the symptomatic treatment of Parkinson's disease (PD). MAO-B inhibitor monotherapy has been shown to be effective and safe for the treatment of early-stage PD, while MAO-B inhibitors as adjuvant drugs have been widely applied for the treatment of the advanced stages of the illness. MAO-B inhibitors can effectively improve patients' motor and non-motor symptoms, reduce "OFF" time, and may potentially prevent/delay disease progression. In this review, we discuss the effects of MAO-B inhibitors on motor and non-motor symptoms in PD patients, their mechanism of action, and the future development of MAO-B inhibitor therapy.

Helicobacter pylori eradication improves motor fluctuations in advanced Parkinson's disease patients: A prospective cohort study (HP-PD trial)

BACKGROUND

Helicobacter pylori (HP) is a bacterium associated with many gastrointestinal (GI) diseases and has shown a high prevalence in Parkinson's disease (PD). As HP-associated GI dysfunction could affect L-dopa (levodopa) absorption, HP eradication might improve the clinical response and decrease motor fluctuations.

METHODS

A prospective cohort study was conducted on the clinical symptoms of PD patients with motor fluctuations. The 13C-urea breath test was used to diagnose a current HP infection. All patients with HP infection received a 2-week regimen of triple therapy. The changes in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score, L-dopa onset time, wearing-off symptoms, mean daily on-off time, GI symptom scores, and quality of life score were measured at baseline and at a 6-week follow-up.

RESULTS

A total of 163 PD patients were assessed, of whom 40 were enrolled. Fifty-five percent of the enrolled patients (22/40) had a current HP infection, whereas HP eradication was identified in 17 of 22 (77.3%) patients who received eradication therapy. Patients with HP eradication showed a significant decrease in daily 'off' time (4.0 vs. 4.7 h, p = 0.040) and an increase in daily 'on' time (11.8 vs. 10.9 h, p = 0.009). Total wearing-off score (4.4 vs. 6.0, p = 0.001) and the GI symptom score (8.1 vs. 12.8, p = 0.007) were significantly improved. There was no significant improvement in L-dopa onset time, UPDRS motor score, or quality of life score.

CONCLUSIONS

HP eradication leads to significant clinical improvement in the symptoms of PD. Eradication of HP not only increases the total daily 'on' time but also decreases wearing-off symptoms and improves GI symptoms.

Therapeutic Strategies to Treat or Prevent Off Episodes in Adults with Parkinson's Disease

Parkinson's disease is a chronic, neurodegenerative disease, which manifests with a mixture of motor, cognitive and behavioural symptoms. Levodopa is the most effective antiparkinsonian treatment to date, although chronic use engenders a mixture of complications in a substantial proportion of patients. Amongst these is the occurrence of episodes of worsening symptoms-'off' phenomena. These episodes can manifest with either motor or non-motor symptoms or a combination of these features and have been found to have profound impacts on patients' quality of life. Although preventative measures are poorly evidenced, avoiding excessive total daily levodopa intake in selected populations that are deemed to be of a higher risk for developing these episodes warrants further exploration. Methods to improve levodopa bioavailability and delivery to the brain are currently available and are of value in addressing these episodes once they have become established. These include modifications to levodopa formulations as well as the use of complimentary agents that improve levodopa bioavailability. The deployment of device-assisted approaches is a further dimension that can be considered in addressing these debilitating episodes. This review summarises the clinical manifestations of 'off' phenomena and the current approaches to treat them. Although we briefly discuss clinical advances on the horizon, the predominant focus is on existing, established treatments.

A case study of foliglurax, the first clinical mGluR4 PAM for symptomatic treatment of Parkinson's disease: translational gaps or a failing industry innovation model?

INTRODUCTION

Approximately 40% of Parkinson's disease (PD) patients that take mostly dopamine receptor agonists for motor fluctuations, experience the return of symptoms between regular doses. This is a phenomenon known as 'OFF periods.' Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 4 (mGluR4) are a promising non-dopaminergic mechanism with potential to address the unmet need of patients suffering from OFF periods. Foliglurax is the first mGluR4 PAM that has advanced into clinical testing in PD patients.

AREAS COVERED

We summarize the chemistry, pharmacokinetics, and preclinical pharmacology of foliglurax. Translational PET imaging studies, clinical efficacy data, and a competitive landscape analysis of available therapies are presented to the readers. In this Perspective article, foliglurax is used as a case study to illustrate the inherent R&D challenges that companies face when developing drugs. These challenges include the delivery of drugs acting through novel mechanisms, long-term scientific investment, and commercial success and shorter-term positive financial returns.

EXPERT OPINION

Failure to meet the primary and secondary endpoints in a Phase 2 study led Lundbeck to discontinue the development of foliglurax. Understanding the evidence supporting compound progression into Phase 2 will enable the proper assessment of the therapeutic potential of mGluR4 PAMs.

Contemporary Options for the Management of Motor Complications in Parkinson's Disease: Updated Clinical Review

Parkinson's disease (PD) is a chronic, progressive condition affecting around 1% of the population older than 60 years. Upon long-term treatment with levodopa, the mainstay of treatment in PD, most patients, especially younger ones exposed to higher doses, will experience symptoms related to end-of-dose deterioration, peak-dose dyskinesias, and other motor fluctuations. Therapeutic strategies are grounded on modification of oral levodopa pharmacokinetics to extend levodopa benefit and development of new routes of drug delivery (e.g., levodopa/carbidopa intestinal gel infusion) or long-acting formulations of existing dopaminergic drugs to prolong the duration of striatal dopamine receptors stimulation. As our understanding of the pathophysiology of motor complications evolves, our therapeutic armamentarium is actively expanding and the focus of research is now actively pointing to the new non-dopaminergic agents acting both within the basal ganglia and in other brain regions (e.g., drugs acting on glutamate, GABA, serotonin, and calcium channels). Despite the fact that trials comparing the different therapeutic strategies are lacking, we aimed at devising practical evidence- and experience-guided suggestions for the clinical management of motor complications, emphasizing that this should always be an individualized endeavor. This review summarizes the pharmacological management of motor complications in PD, including new formulations and routes of delivery, and the newer released drugs such as istradefylline, opicapone, safinamide, and zonisamide. Advanced therapeutic strategies for selected cases such as treatment with apomorphine and surgical techniques (deep brain stimulation) are also discussed. A comprehensive knowledge of the available options and evidence is fundamental for the successful management of these challenging complications.

Selegiline: a molecule with innovative potential

Monoamine oxidase B (MAO-B) inhibitors have an established role in the treatment of Parkinson's disease as monotherapy or adjuvant to levodopa. Two major recognitions were required for their introduction into this therapeutic field. The first was the elucidation of the novel pharmacological properties of selegiline as a selective MAO-B inhibitor by Knoll and Magyar and the original idea of Riederer and Youdim, supported by Birkmayer, to explore its effect in parkinsonian patients with on-off phases. In the 1960s, MAO inhibitors were mainly studied as potential antidepressants, but Birkmayer found that combined use of levodopa and various MAO inhibitors improved akinesia in Parkinson's disease. However, the serious side effects of the first non-selective MAO inhibitors prevented their further use. Later studies demonstrated that MAO-B, mainly located in glial cells, is important for dopamine metabolism in the brain. Recently, cell and molecular studies revealed interesting properties of selegiline opening new possibilities for neuroprotective mechanisms and a disease-modifying effect of MAO-B inhibitors.

Rasagiline combined with levodopa therapy versus levodopa monotherapy for patients with Parkinson's disease: a systematic review

OBJECTIVE

The aim of this report was to systematically evaluate the efficacy and safety of rasagiline (R) plus levodopa (L) (R + L) for the treatment of Parkinson's disease (PD) compared with that of L monotherapy, in order to provide a reference resource for rational drug use.

METHODS

Randomized controlled trials (RCTs) of R + L for PD published up to September 2018 were searched. Sensitivity analyses were also performed.

RESULTS

Fourteen RCTs with 2531 participants were included. Compared with L monotherapy, the pooled effects of R + L combination therapy on unified Parkinson's disease rating scale (UPDRS) score were (SMD - 0.50, 95% CI - 0.70 to - 0.30, P < 0.00001) for UPDRS motor score, (SMD - 0.59, 95% CI - 0.79 to - 0.39, P < 0.00001) for UPDRS activities of daily living (ADL) score, (SMD - 0.65, 95% CI - 0.81 to - 0.49, P < 0.00001) for UPDRS total score. R + L combination therapy was better than L monotherapy in reducing daily off-time (SMD - 1.15, 95% CI - 2.13 to - 0.17, P = 0.02), but there was a statistically nonsignificant result in daily on-time increase (SMD 1.39, 95% CI - 0.69 to 3.48, P = 0.19). There were no statistical differences in number of adverse events (OR 1.33, 95% CI 0.97 to 1.82, P = 0.07) and number of dropout (OR 0.88, 95% CI 0.65 to 1.19, P = 0.39) between R + L combination therapy and L monotherapy.

CONCLUSIONS

R + L combination therapy was superior to L monotherapy for improvement of UPDRS scores and off-time in PD patients. Moreover, R + L combination therapy and L monotherapy were similar in terms of safety and tolerability.

Different Generations of Type-B Monoamine Oxidase Inhibitors in Parkinson's Disease: From Bench to Bedside

Three inhibitors of type-B monoamine oxidase (MAOB), selegiline, rasagiline, and safinamide, are used for the treatment of Parkinson's disease (PD). All three drugs improve motor signs of PD, and are effective in reducing motor fluctuations in patients undergoing long-term L-DOPA treatment. The effect of MAOB inhibitors on non-motor symptoms is not uniform and may not be class-related. Selegiline and rasagiline are irreversible inhibitors forming a covalent bond within the active site of MAOB. In contrast, safinamide is a reversible MAOB inhibitor, and also inhibits voltage- sensitive sodium channels and glutamate release. Safinamide is the prototype of a new generation of multi-active MAOB inhibitors, which includes the antiepileptic drug, zonisamide. Inhibition of MAOB-mediated dopamine metabolism largely accounts for the antiparkinsonian effect of the three drugs. Dopamine metabolism by MAOB generates reactive oxygen species, which contribute to nigro-striatal degeneration. Among all antiparkinsonian agents, MAOB inhibitors are those with the greatest neuroprotective potential because of inhibition of dopamine metabolism, induction of neurotrophic factors, and, in the case of safinamide, inhibition of glutamate release. The recent development of new experimental animal models that more closely mimic the progressive neurodegeneration associated with PD will allow to test the hypothesis that MAOB inhibitors may slow the progression of PD.

New Frontiers in Selective Human MAO-B Inhibitors

Accumulating evidence shows a relationship between the human MAO-B (hMAO-B) enzyme and neuropsychiatric/degenerative disorder, personality traits, type II alcoholism, borderline personality disorders, aggressiveness and violence in crime, obsessive-compulsive disorder, depression, suicide, schizophrenia, anorexia nervosa, migraine, dementia, and PD. Thus, MAO-B represents an attractive target for the treatment of a number of human diseases. The discovery, development, and therapeutic use of drugs that inhibit MAO-B are major challenges for future therapy. Various compounds and drugs that selectively target this isoform have been discovered recently. These agents are synthetic compounds or natural products and their analogues, including chalcones, pyrazoles, chromones, coumarins, xanthines, isatin derivatives, thiazolidindiones, (thiazol-2-yl)hydrazones, and analogues of marketed drugs. Despite considerable efforts in understanding the binding interaction with specific substrates or inhibitors, structural information available for the rational design of new hMAO-B inhibitors remains unsatisfactory. Therefore, the quest for novel, potent, and selective hMAO-B inhibitors remains of high interest.

Treatment of advanced Parkinson's disease

PURPOSE OF REVIEW

Later stage Parkinson's disease, sometimes referred to as advanced disease, has been characterized by motor complication, as well as by the potential emergence of nonlevodopa responsive motor and nonmotor symptoms. The management of advanced stage Parkinson's disease can be complex. This review summarizes the currently available treatment strategies for addressing advanced Parkinson's disease.

RECENT FINDINGS

We will discuss the latest pharmacological strategies (e.g., inhibitors of dopamine-metabolizing enzymes, dopamine agonists, and extended release dopamine formulations) for addressing motor dysfunction. We will summarize the risks and benefits of current invasive treatments. Finally, we will address the current evidence supporting the treatment of nonmotor symptoms in the advanced Parkinson's disease patient. We will conclude by detailing the potential nonpharmacological and multidisciplinary approaches for advanced stage Parkinson's disease.

SUMMARY

The optimization of levodopa is, in most cases, the most powerful therapeutic option available; however, medication optimization requires an advanced understanding of Parkinson's disease. Failure of conventional pharmacotherapy should precipitate a discussion of the potential risks and benefits of more invasive treatments. Currently, there are no comparative studies of invasive treatment. Among the invasive treatments, deep brain stimulation has the largest amount of existing evidence, but also has the highest individual per patient risk. Nonmotor symptoms will affect quality of life more than the motor Parkinson's disease symptoms, and these nonmotor symptoms should be aggressively treated. Many advanced Parkinson's disease patients will likely benefit from multi and interdisciplinary Parkinson's disease teams with multiple professionals collaborating to develop a collective and tailored strategy for an individual patient.

Symptomatic efficacy of rasagiline monotherapy in early Parkinson's disease: post-hoc analyses from the ADAGIO trial

BACKGROUND

The ADAGIO study included a large cohort of patients with early PD (baseline total-UPDRS = 20) who were initially randomized to rasagiline and placebo, thereby allowing analyses of symptomatic efficacy.

METHODS

Post-hoc analyses comparing the efficacy of rasagiline 1 mg/day (n = 288) versus placebo (n = 588) on key symptoms at 36 weeks, and on total-UPDRS scores over 72 weeks (completer population: rasagiline 1 mg/day n = 221, placebo n = 392) were performed.

RESULTS

Treatment with rasagiline resulted in significantly better tremor, bradykinesia, rigidity and postural-instability-gait-difficulty scores at week 36 versus placebo. Whereas the placebo group experienced progressive deterioration from baseline (2.6 UPDRS points at week 36), patients in the rasagiline group were maintained at baseline values at week 60 (UPDRS-change of 0.3 points). At week 72, patients who had received continuous monotherapy with rasagiline experienced a worsening of only 1.6 points.

CONCLUSIONS

Treatment with rasagiline maintained motor function to baseline values for at least a year with significant benefits observed in all key PD motor symptoms.

Rasagiline and rapid symptomatic motor effect in Parkinson's disease: review of literature

Rasagiline is a monoamine oxidase type-B inhibitor used as monotherapy or in addition to levodopa in the treatment of Parkinson's disease. Once daily administration of rasagiline makes it easy to use, and allows good compliance by patients and adherence to therapy. Several multicenter studies have noted the effectiveness of rasagiline on both motor and non-motor symptoms, which require a complex pharmacologic approach, such as cognitive disorders. A recent study also reported a rapid action of rasagiline on motor symptoms. Positive findings have been highlighted by an economic model study. This review analyzes the main studies of rasagiline, with particular attention to the effectiveness of the drug on motor symptoms.