Cost-effectiveness of droxidopa in patients with neurogenic orthostatic hypotension: post-hoc economic analysis of Phase 3 clinical trial data

OBJECTIVE

Falls are associated with neurogenic orthostatic hypotension (nOH) and are an economic burden on the US healthcare system. Droxidopa is approved by the US FDA to treat symptomatic nOH. This study estimates the cost-effectiveness of droxidopa vs standard of care from a US payer perspective.

METHODS

A Markov model was used to predict numbers of falls and treatment responses using data from a randomized, double-blind trial of patients with Parkinson's disease and nOH who received optimized droxidopa therapy or placebo for 8 weeks. The severity of falls, utility values, and injury-related costs were derived from published studies. Model outcomes included number of falls, number of quality-adjusted life-years (QALYs), and direct costs. Incremental cost-effectiveness ratios (ICERs) were calculated. Outcomes were extrapolated over 12 months.

RESULTS

Patients receiving droxidopa had fewer falls compared with those receiving standard of care and gained 0.33 QALYs/patient. Estimated droxidopa costs were $30,112, with estimated cost savings resulting from fall avoidance of $14,574 over 12 months. Droxidopa was cost-effective vs standard of care, with ICERs of $47,001/QALY gained, $24,866 per avoided fall with moderate/major injury, and $1559 per avoided fall with no/minor injury. The main drivers were fall probabilities and fear of fall-related inputs.

LIMITATIONS

A limitation of the current study is the reliance on falls data from a randomized controlled trial where the placebo group served as the proxy for standard of care. Data from a larger patient population, reflecting 'real-life' patient use and/or comparison with other agents used to treat nOH, would have been a useful complement, but these data were not available.

CONCLUSION

Using Markov modeling, droxidopa appears to be a cost-effective option compared with standard of care in US clinical practice for the treatment of nOH.

Carbidopa levodopa enteral suspension

INTRODUCTION

The search for consistent, effective treatments in Parkinson's disease (PD) is ongoing. The importance of continuous dopaminergic stimulation (CDS) is understood to underlie best medical therapy for PD by providing closer replication of physiological patterns of dopamine release in healthy brains.

AREAS COVERED

An overview of interventions to improve motor fluctuations in PD is presented. Significant improvements in off-time are achieved by providing continuous therapy using targeted deep brain stimulation (DBS), subcutaneous apomorphine infusion and carbidopa/levodopa enteral suspension (Duopa). Duopa is a newly approved treatment in the US for advanced PD that delivers levodopa pumped to the intestinal tract through a percutaneous gastrostomy with jejunum tube extension (PEG-J tube). Trials with carbidopa/levodopa enteral suspension show improvement in motor fluctuations, reduction in plasma levodopa variation and improvement in overall "on" time compared with oral immediate release formulation of carbidopa/levodopa.

EXPERT OPINION

The degree of improvement in number of off hours per day on carbidopa/levodopa enteral suspension infusion rivals that seen with DBS and apomorphine infusion and makes this new treatment a valuable option in advanced fluctuating PD patients, especially those who are neither candidates for DBS or who do not have access to apomorphine infusion therapy or who have failed either or both therapies.

NBI-98854, a selective monoamine transport inhibitor for the treatment of tardive dyskinesia: A randomized, double-blind, placebo-controlled study

BACKGROUND

Tardive dyskinesia is a persistent movement disorder induced by chronic neuroleptic exposure. NBI-98854 is a novel, highly selective, vesicular monoamine transporter 2 inhibitor. We present results of a randomized, 6-week, double-blind, placebo-controlled, dose-titration study evaluating the safety, tolerability, and efficacy of NBI-98854 for the treatment of tardive dyskinesia.

METHODS

Male and female adult subjects with moderate or severe tardive dyskinesia were included. NBI-98854 or placebo was given once per day starting at 25 mg and then escalated by 25 mg to a maximum of 75 mg based on dyskinesia and tolerability assessment. The primary efficacy endpoint was the change in Abnormal Involuntary Movement Scale from baseline at week 6 scored by blinded, central video raters. The secondary endpoint was the Clinical Global Impression of Change-Tardive Dyskinesia score assessed by the blinded investigator.

RESULTS

Two hundred five potential subjects were screened, and 102 were randomized; 76% of NBI-98854 subjects and 80% of placebo subjects reached the maximum allowed dose. Abnormal Involuntary Movement Scale scores for NBI-98854 compared with placebo were significantly reduced (p = 0.0005). Active drug was also superior on the Clinical Global Impression of Change-Tardive Dyskinesia (p < 0.0001). Treatment-emergent adverse event rates were 49% in the NBI-98854 and 33% in the placebo subjects. The most common adverse events (active vs. placebo) were fatigue and headache (9.8% vs. 4.1%) and constipation and urinary tract infection (3.9% vs. 6.1%). No clinically relevant changes in safety assessments were noted.

CONCLUSION

NBI-98854 significantly improved tardive dyskinesia and was well tolerated in patients. These results support the phase 3 clinical trials of NBI-98854 now underway.

Mavoglurant (AFQ056) in combination with increased levodopa dosages in Parkinson's disease patients

Long-term use of levodopa (L-dopa) in patients with Parkinson's disease is associated with development of dyskinesia. This study explored whether Parkinson's disease patients with L-dopa-induced dyskinesia experience improved OFF-time from higher L-dopa doses without worsening of dyskinesias when receiving adjunctive mavoglurant. Patients with moderate-to-severe L-dopa-induced dyskinesia were randomized to receive mavoglurant or placebo. Mavoglurant (AFQ056) was up-titrated over two weeks from 25 mg twice daily (bid) to 100 mg bid (L-dopa kept stable), followed by three weeks during which the daily L-dopa dosage was increased by up to 300 mg/day. A sample size of 30 was initially planned; however, the study was terminated prematurely due to enrollment challenges. OFF-time showed greater improvements in the mavoglurant group (n = 7) compared with the placebo group (n = 7); difference at week 5 was -2.77 h (90% confidence interval -5.44, -0.09 h; p = 0.09). ON-time without troublesome dyskinesia increased more from baseline to week 5 in the mavoglurant group (4.38 h) versus the placebo group (0.63 h). Clinician-rated measures were conflicting. The Modified Abnormal Involuntary Movement Scale scores showed a slight improvement with mavoglurant compared with placebo, while the Unified Dyskinesia Rating Scale parts III and IV worsened slightly with mavoglurant compared with placebo. Due to the low patient numbers and conflicting clinician-rated outcomes data, our findings are not conclusive. However, our results suggest that mavoglurant combined with higher doses of L-dopa may be effective in treating patients with Parkinson's disease experiencing L-dopa-related motor fluctuations and dyskinesias.

Amantadine extended release for levodopa-induced dyskinesia in Parkinson's disease (EASED Study)

ADS-5102 is a long-acting, extended-release capsule formulation of amantadine HCl administered once daily at bedtime. This study investigated the safety, efficacy, and tolerability of ADS-5102 in Parkinson's disease (PD) patients with levodopa-induced dyskinesia. This was a randomized, double-blind, placebo-controlled, parallel-group study of 83 PD patients with troublesome dyskinesia assigned to placebo or one of three doses of ADS-5102 (260 mg, 340 mg, 420 mg) administered daily at bedtime for 8 weeks. The primary efficacy analysis compared change from baseline to week 8 in Unified Dyskinesia Rating Scale (UDysRS) total score for 340 mg ADS-5102 versus placebo. Secondary outcome measures included change in UDysRS for 260 mg, 420 mg, Fatigue Severity Scale (FSS), Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS), patient diary, Clinician's Global Impression of Change, and Parkinson's Disease Questionnaire (PDQ-39). ADS-5102 340 mg significantly reduced dyskinesia versus placebo (27% reduction in UDysRS, P = 0.005). In addition, ADS-5102 significantly increased ON time without troublesome dyskinesia, as assessed by PD patient diaries, at 260 mg (P = 0.004), 340 mg (P = 0.008) and 420 mg (P = 0.018). Adverse events (AEs) were reported for 82%, 80%, 95%, and 90% of patients in the placebo, 260-mg, 340-mg, and 420-mg groups, respectively. Constipation, hallucinations, dizziness, and dry mouth were the most frequent AEs. Study withdrawal rates were 9%, 15%, 14%, and 40% for the placebo, 260-mg, 340-mg, and 420-mg groups, respectively. All study withdrawals in the active treatment groups were attributable to AEs. ADS-5102 was generally well tolerated and resulted in significant and dose-dependent improvements in dyskinesia in PD patients.

Effects of rasagiline on the progression of nonmotor scores of the MDS-UPDRS

BACKGROUND

A draft version of part 1 (Non-Motor Aspects of Experiences of Daily Living; nM-EDL) of the MDS-UPDRS scale was employed as a secondary outcome in the ADAGIO study, which assessed the effect of rasagiline in early Parkinson's disease (PD) patients.

METHODS

This analysis includes 1,150 untreated PD patients randomized to placebo or rasagiline 1 or 2 mg/day for 36 weeks in the placebo-controlled phase of ADAGIO who had draft-nM-EDL assessments at baseline and week 36.

RESULTS

Over the 9-month placebo-controlled phase of the study, nM-EDL scores significantly deteriorated from baseline in the placebo group only (0.34 ± 0.10 units; P < 0.001). Compared to the placebo group (n = 583), there was significantly less deterioration in the 1-mg/day rasagiline group (n = 280; treatment effect: -0.33 units; P < 0.05), whereas the treatment effect in the 2-mg/day rasagiline group (n = 287) was not statistically significant (-0.25 ± 0.17 units; P = 0.131).

CONCLUSIONS

The nM-EDL subscale appears sensitive to change in very early PD, and treatment with rasagiline 1 mg/day was associated with significantly less decline in nonmotor experiences of daily living versus placebo. Given that score changes were numerically small, the clinical implications of this effect remain unclear.

Levodopa-carbidopa intestinal gel in advanced Parkinson's disease: final 12-month, open-label results

Motor complications in Parkinson's disease (PD) are associated with long-term oral levodopa treatment and linked to pulsatile dopaminergic stimulation. l-dopa-carbidopa intestinal gel (LCIG) is delivered continuously by percutaneous endoscopic gastrojejunostomy tube (PEG-J), which reduces l-dopa-plasma–level fluctuations and can translate to reduced motor complications. We present final results of the largest international, prospective, 54-week, open-label LCIG study. PD patients with severe motor fluctuations (>3 h/day “off” time) despite optimized therapy received LCIG monotherapy. Additional PD medications were allowed >28 days post-LCIG initiation. Safety was the primary endpoint measured through adverse events (AEs), device complications, and number of completers. Secondary endpoints included diary-assessed off time, “on” time with/without troublesome dyskinesia, UPDRS, and health-related quality-of-life (HRQoL) outcomes. Of 354 enrolled patients, 324 (91.5%) received PEG-J and 272 (76.8%) completed the study. Most AEs were mild/moderate and transient; complication of device insertion (34.9%) was the most common. Twenty-seven (7.6%) patients withdrew because of AEs. Serious AEs occurred in 105 (32.4%), most commonly complication of device insertion (6.5%). Mean daily off time decreased by 4.4 h/65.6% (P < 0.001). On time without troublesome dyskinesia increased by 4.8 h/62.9% (P < 0.001); on time with troublesome dyskinesia decreased by 0.4 h/22.5% (P = 0.023). Improvements persisted from week 4 through study completion. UPDRS and HRQoL outcomes were also improved throughout. In the advanced PD population, LCIG's safety profile consisted primarily of AEs associated with the device/procedure, l-dopa/carbidopa, and advanced PD. LCIG was generally well tolerated and demonstrated clinically significant improvements in motor function, daily activities, and HRQoL sustained over 54 weeks. © 2014 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Droxidopa for the short-term treatment of symptomatic neurogenic orthostatic hypotension in Parkinson's disease (nOH306B)

Neurogenic orthostatic hypotension (nOH) results from failure of norepinephrine responses to postural change to maintain standing systolic blood pressure (s-SBP). Droxidopa is an oral prodrug of norepinephrine. Study nOH306 enrolled patients with Parkinson's disease (PD) and symptomatic nOH. Subjects underwent up to 2 weeks of double-blind titration of droxidopa or placebo, followed by 8 weeks of double-blind maintenance treatment (100-600 mg thrice-daily). For the initial 51 subjects (study nOH306A, previously reported), the primary efficacy measure, Orthostatic Hypotension Questionnaire (OHQ) composite score, did not demonstrate significant change versus placebo at maintenance week 8. For the subsequent 171 subjects (study nOH306B, reported here), the primary efficacy measure was change versus placebo on item 1 ("dizziness, lightheadedness, feeling faint, or feeling like you might black out") of the Orthostatic Hypotension Symptom Assessment (OHSA) subsection of the OHQ at maintenance week 1. At week 1, mean (standard deviation) improvement on OHSA item 1 was 2.3 (2.95) for droxidopa versus 1.3 (3.16) for placebo (P = 0.018). In addition, mean increase in s-SBP at week 1 was 6.4 (18.85) for droxidopa versus 0.7 (20.18) mmHg for placebo (nominal P value: 0.032). Differences in change in OHSA item 1 scores from baseline to maintenance weeks 2, 4, and 8 were not statistically significant. Adverse-event (AE) incidence was similar across groups, but 12.4% of droxidopa and 6.1% of placebo subjects withdrew because of AEs. The most common AEs on droxidopa (vs. placebo) were headache (13.5% vs. 7.3%) and dizziness (10.1% vs. 4.9%). Study nOH306B demonstrated subjective (OHSA item 1) and objective (s-SBP) evidence of short-term droxidopa efficacy (vs. placebo) for symptomatic nOH in PD.

Long-term safety and sustained efficacy of extended-release pramipexole in early and advanced Parkinson's disease

BACKGROUND AND PURPOSE

To assess the long-term safety and efficacy of pramipexole as a once-daily (q.d.) extended-release oral formulation in early or advanced Parkinson's disease (PD).

METHODS

In two double-blind (DB) studies of early PD and one of advanced PD,active-treatment arms received pramipexole immediate release (IR) or extended release (ER), with exposure lasting up to 33 weeks. In open-label (OL) extensions that followed immediately, subjects took ER q.d. for up to 80 weeks, with dosage adjustment permitted (range 0.375-4.5 mg q.d.).

RESULTS

Of 590 subjects completing an early-PD DB study, 511 entered the early-PD OL extension; 408 completed it. Reported adverse events (AEs) with incidence ≥10.0% were somnolence (15.1%), peripheral edema (11.7%) and back pain (10.6%). Of 465 subjects completing the advanced-PD DB study, 391 entered the advanced-PD OL extension; 329 completed it. Reported AEs with incidence ≥10.0%were dyskinesia (27.4%) and somnolence (13.6%). Impulse control disorders were identified by semi-structured interview in 13 subjects (1.4% of 902). In exploratory analyses, adjusted mean Unified Parkinson's Disease Rating Scale (UPDRS) PartsII + III scores (excluding ex-placebo recipients) remained substantially improved from DB baseline scores prior to pramipexole introduction, at -6.6 and -6.3 points amongst ex-DB-ER and ex-DB-IR recipients after 113 weeks of pramipexole (33 DB plus 80 OL) in early PD, and -11.5 and -9.1 after up to 113 weeks (up to 33 DB plus 80 OL) in advanced PD.

CONCLUSIONS

These results support the long-term safety and efficacy of pramipexole ER in early and advanced PD. AEs were typical for dopaminergic medications, and UPDRS scores suggested sustained symptomatic benefit.

Droxidopa in patients with neurogenic orthostatic hypotension associated with Parkinson's disease (NOH306A)

BACKGROUND

Neurogenic orthostatic hypotension (nOH) is common in Parkinson's disease (PD), and represents a failure to generate norepinephrine responses appropriate for postural change. Droxidopa (L-threo-3,4-dihydroxyphenylserine) is an oral norepinephrine prodrug.

OBJECTIVE

Interim analyses of the initial patients enrolled in a multicenter, randomized, double-blind, placebo-controlled phase 3 trial of droxidopa for nOH in PD (ClinicalTrials.gov Identifier: NCT01176240).

METHODS

PD patients with documented nOH underwent ≤ 2 weeks of double-blind droxidopa or placebo dosage optimization followed by 8 weeks of maintenance treatment (100-600 mg t.i.d.). The primary efficacy measure was change in Orthostatic Hypotension Questionnaire (OHQ) composite score from baseline to Week 8. Key secondary variables included dizziness/lightheadedness score (OHQ item 1) and patient-reported falls.

RESULTS

Among 24 droxidopa and 27 placebo recipients, mean OHQ composite-score change at Week 8 was -2.2 versus -2.1 (p = 0.98); in response to this pre-planned futility analysis, the study was temporarily stopped and all data from these patients were considered exploratory. At Week 1, mean dizziness/lightheadedness score change favored droxidopa by 1.5 units (p = 0.24), with subsequent numerical differences favoring droxidopa throughout the observation period, and at Week 1, mean standing systolic blood-pressure change favored droxidopa by 12.5 mmHg (p = 0.04). Compared with placebo, the droxidopa group exhibited an approximately 50% lower rate of reported falls (p = 0.16) and fall-related injuries (post-hoc analysis).

CONCLUSIONS

This exploratory analysis of a small dataset failed to show benefit of droxidopa, as compared with placebo by the primary endpoint. Nonetheless, there were signals of potential benefit for nOH, including improvement in dizziness/lightheadedness and reduction in falls, meriting evaluation in further trials.

Association between Hoehn and Yahr, Mini-Mental State Examination, age, and clinical syndrome predominance and diagnostic effectiveness of ioflupane I 123 injection (DaTSCAN™) in subjects with clinically uncertain parkinsonian syndromes

Introduction

Diagnostic effectiveness of Ioflupane I 123 injection (DaTSCAN™, DaTscan™, or [123I]FP-CIT or ioflupane [¹²³I]) SPECT imaging, was assessed in patients with clinically uncertain parkinsonian syndrome (CUPS).

Methods

We investigated the association between subject’s Hoehn & Yahr (H&Y) stage, Mini-Mental State Examination (MMSE), age, and motor symptom subgroups and diagnostic performance of ioflupane [¹²³I] imaging. Phase 4 study data were used to calculate sensitivity, specificity, positive and negative predictive value, and accuracy in 92 CUPS subjects, using 1-year clinical diagnosis after ioflupane [¹²³I] imaging as reference standard.

Results

Diagnostic effectiveness of ioflupane [¹²³I] imaging was high in all subgroups: 91% to 100% for H&Y low (<2) and high (≥2) stage subjects; 93% to 96% for MMSE low (<29) or high (≥29) scores; 91% to100% in both age subgroups (younger [<68] and older [≥68]); and 92% to 100% in subjects with both tremor dominant and balanced motor signs. Specificity of ioflupane [¹²³I] imaging for bradykinetic rigid or posturally (BRP) unstable motor subtype was lower, but better than for baseline clinical diagnosis.

Conclusions

Strongest diagnostic performance of ioflupane [¹²³I] imaging for clinical diagnosis of Parkinson’s syndrome (PS) or non-PS was associated with tremor and balanced motor dominance rather than with BRP dominance. High diagnostic effectiveness of ioflupane [¹²³I] imaging and favourable performance relative to final clinical diagnosis at 1 year post-scan in subjects with CUPS was demonstrated. This study suggests that the diagnostic performance of ioflupane [¹²³I] imaging in CUPS remains high at all stages of disease, including early stage, and across both age groups and cognitive state (MMSE).

A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit

IMPORTANCE

Coenzyme Q10 (CoQ10), an antioxidant that supports mitochondrial function, has been shown in preclinical Parkinson disease (PD) models to reduce the loss of dopamine neurons, and was safe and well tolerated in early-phase human studies. A previous phase II study suggested possible clinical benefit.

OBJECTIVE

To examine whether CoQ10 could slow disease progression in early PD.

DESIGN, SETTING, AND PARTICIPANTS

A phase III randomized, placebo-controlled, double-blind clinical trial at 67 North American sites consisting of participants 30 years of age or older who received a diagnosis of PD within 5 years and who had the following inclusion criteria: the presence of a rest tremor, bradykinesia, and rigidity; a modified Hoehn and Yahr stage of 2.5 or less; and no anticipated need for dopaminergic therapy within 3 months. Exclusion criteria included the use of any PD medication within 60 days, the use of any symptomatic PD medication for more than 90 days, atypical or drug-induced parkinsonism, a Unified Parkinson's Disease Rating Scale (UPDRS) rest tremor score of 3 or greater for any limb, a Mini-Mental State Examination score of 25 or less, a history of stroke, the use of certain supplements, and substantial recent exposure to CoQ10. Of 696 participants screened, 78 were found to be ineligible, and 18 declined participation.

INTERVENTIONS

The remaining 600 participants were randomly assigned to receive placebo, 1200 mg/d of CoQ10, or 2400 mg/d of CoQ10; all participants received 1200 IU/d of vitamin E.

MAIN OUTCOMES AND MEASURES

Participants were observed for 16 months or until a disability requiring dopaminergic treatment. The prospectively defined primary outcome measure was the change in total UPDRS score (Parts I-III) from baseline to final visit. The study was powered to detect a 3-point difference between an active treatment and placebo.

RESULTS

The baseline characteristics of the participants were well balanced, the mean age was 62.5 years, 66% of participants were male, and the mean baseline total UPDRS score was 22.7. A total of 267 participants required treatment (94 received placebo, 87 received 1200 mg/d of CoQ10, and 86 received 2400 mg/d of CoQ10), and 65 participants (29 who received placebo, 19 who received 1200 mg/d of CoQ10, and 17 who received 2400 mg/d of CoQ10) withdrew prematurely. Treatments were well tolerated with no safety concerns. The study was terminated after a prespecified futility criterion was reached. At study termination, both active treatment groups showed slight adverse trends relative to placebo. Adjusted mean changes (worsening) in total UPDRS scores from baseline to final visit were 6.9 points (placebo), 7.5 points (1200 mg/d of CoQ10; P = .49 relative to placebo), and 8.0 points (2400 mg/d of CoQ10; P = .21 relative to placebo).

CONCLUSIONS AND RELEVANCE

Coenzyme Q10 was safe and well tolerated in this population, but showed no evidence of clinical benefit.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00740714.

Tozadenant (SYN115) in patients with Parkinson's disease who have motor fluctuations on levodopa: a phase 2b, double-blind, randomised trial

BACKGROUND

Many patients with Parkinson's disease have motor fluctuations despite treatment with available drugs. Tozadenant (SYN115) is an oral, selective adenosine A2A receptor antagonist that improves motor function in animal models of Parkinson's disease. We aimed to assess the safety and efficacy of tozadenant as an adjunct to levodopa in patients with Parkinson's disease who have motor fluctuations on levodopa.

METHODS

We did an international, multicentre, phase 2b, randomised, double-blind, placebo-controlled, parallel-group, dose-finding clinical trial of tozadenant in levodopa-treated patients with Parkinson's disease who had motor fluctuations (at least 2·5 h off-time per day). Eligible patients were randomly assigned via a computer-generated randomisation schedule to receive tozadenant 60, 120, 180, or 240 mg or matching placebo twice daily for 12 weeks. All study management, site personnel, and patients were masked to treatment assignment. The primary outcome was change from baseline to week 12 in hours per day spent in the off-state (assessed from Parkinson's disease diaries completed by patients). This study is registered at ClinicalTrials.gov, number NCT01283594.

FINDINGS

Of 420 randomised patients (mean age 63·3 [SD 8·3] years; mean duration of Parkinson's disease 8·7 [4·7] years), 403 provided post-baseline diary data and 337 completed study treatment. Compared with placebo, mean daily off-time was significantly reduced in the combined tozadenant 120 mg twice-daily and 180 mg twice-daily group (-1·1 h, 95% CI -1·8 to -0·5; p=0·0006), the tozadenant 120 mg twice-daily group (-1·1 h, -1·8 to -0·4; p=0.0039), and the tozadenant 180 mg twice-daily group (-1·2 h, -1·9 to -0·4; p=0·0039). The most common adverse events in these groups were dyskinesia (seven [8%] of 84 patients in the placebo group, 13 [16%] of 82 in the 120 mg twice-daily group, and 17 [20%] of 85 in the 180 mg twice-daily group), nausea (three [4%], 9 [11%], and ten [12%]), and dizziness (one [1%], four [5%], and 11 [13%]). Tozadenant 60 mg twice daily was not associated with a significant reduction in off-time, and tozadenant 240 mg twice daily was associated with an increased rate of discontinuation because of adverse events (17 [20%] of 84 patients).

INTERPRETATION

Tozadenant at 120 or 180 mg twice daily was generally well tolerated and was effective at reducing off-time. Further investigation of tozadenant treatment in phase 3 trials is warranted.

FUNDING

Biotie Therapies.

Peptidoglycan recognition protein genes and risk of Parkinson's disease

Increased gut permeability, inflammation, and colonic α-synuclein pathology are present in early Parkinson's disease (PD) and have been proposed to contribute to PD pathogenesis. Peptidoglycan is a structural component of the bacterial cell wall. Peptidoglycan recognition proteins (PGRPs) maintain healthy gut microbial flora by regulating the immune response to both commensal and harmful bacteria. We tested the hypothesis that variants in genes that encode PGRPs are associated with PD risk. Participants in two independent case-control studies were genotyped for 30 single-nucleotide polymorphisms (SNPs) in the four PGLYRP genes. Using logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for potential confounding variables, we conducted analyses in each study, separately and pooled. One SNP failed the assay, and three had little to no variation. The ORs were similar in both study populations. In pooled analyses, three of seven PGLYRP2 SNPs (rs3813135, rs733731, rs892145), one of five PGLYRP3 SNPs (rs2987763), and six of nine PGLYRP4 SNPs (rs10888557, rs12063091, rs3006440, rs3006448, rs3006458, and rs3014864) were significantly associated with PD risk. Association was strongest for PGLYRP4 5'untranslated region (UTR) SNP rs10888557 (GG reference, CG OR 0.6 [95%CI 0.4-0.9], CC OR 0.15 [95%CI 0.04-0.6]; log-additive P-trend, 0.0004). Common variants in PGLYRP genes are associated with PD risk in two independent studies. These results require replication, but they are consistent with hypotheses of a causative role for the gut microbiota and gastrointestinal immune response in PD.

Minimal clinically important difference in Parkinson's disease as assessed in pivotal trials of pramipexole extended release

Background. The minimal clinically important difference (MCID) is the smallest change in an outcome measure that is meaningful for patients. Objectives. To calculate the MCID for Unified Parkinson's Disease Rating Scale (UPDRS) scores in early Parkinson's disease (EPD) and for UPDRS scores and "OFF" time in advanced Parkinson's disease (APD). Methods. We analyzed data from two pivotal, double-blind, parallel-group trials of pramipexole ER that included pramipexole immediate release (IR) as an active comparator. We calculated MCID as the mean change in subjects who received active treatment and rated themselves "a little better" on patient global impression of improvement (PGI-I) minus the mean change in subjects who received placebo and rated themselves unchanged. Results. MCIDs in EPD (pramipexole ER, pramipexole IR) for UPDRS II were -1.8 and -2.0, for UPDRS III -6.2 and -6.1, and for UPDRS II + III -8.0 and -8.1. MCIDs in APD for UPDRS II were -1.8 and -2.3, for UPDRS III -5.2 and -6.5, and for UPDRS II + III -7.1 and -8.8. MCID for "OFF" time (pramipexole ER, pramipexole IR) was -1.0 and -1.3 hours. Conclusions. A range of MCIDs is emerging in the PD literature that provides the basis for power calculations and interpretation of clinical trials.

Efficacy and safety of rifampicin for multiple system atrophy: a randomised, double-blind, placebo-controlled trial

BACKGROUND

No available treatments slow or halt progression of multiple system atrophy, which is a rare, progressive, fatal neurological disorder. In a mouse model of multiple system atrophy, rifampicin inhibited formation of α-synuclein fibrils, the neuropathological hallmark of the disease. We aimed to assess the safety and efficacy of rifampicin in patients with multiple system atrophy.

METHODS

In this randomised, double-blind, placebo-controlled trial we recruited participants aged 30-80 years with possible or probable multiple system atrophy from ten US medical centres. Eligible participants were randomly assigned (1:1) via computer-generated permuted block randomisation to rifampicin 300 mg twice daily or matching placebo (50 mg riboflavin capsules), stratified by subtype (parkinsonian vs cerebellar), with a block size of four. The primary outcome was rate of change (slope analysis) from baseline to 12 months in Unified Multiple System Atrophy Rating Scale (UMSARS) I score, analysed in all participants with at least one post-baseline measurement. This study is registered with ClinicalTrials.gov, number NCT01287221.

FINDINGS

Between April 22, 2011, and April 19, 2012, we randomly assigned 100 participants (50 to rifampicin and 50 to placebo). Four participants in the rifampicin group and five in the placebo group withdrew from study prematurely. Results of the preplanned interim analysis (n=15 in each group) of the primary endpoint showed that futility criteria had been met, and the trial was stopped (the mean rate of change [slope analysis] of UMSARS I score was 0.62 points [SD 0.85] per month in the rifampicin group vs 0.47 points [0.48] per month in the placebo group; futility p=0.032; efficacy p=0.76). At the time of study termination, 49 participants in the rifampicin group and 50 in the placebo group had follow-up data and were included in the final analysis. The primary endpoint was 0.5 points (SD 0.7) per month for rifampicin and 0.5 points (0.5) per month for placebo (difference 0.0, 95% CI -0.24 to 0.24; p=0.82). Three (6%) of 50 participants in the rifampicin group and 12 (24%) of 50 in the placebo group had one or more serious adverse events; none was thought to be related to treatment.

INTERPRETATION

Our results show that rifampicin does not slow or halt progression of multiple system atrophy. Despite the negative result, the trial does provide information that could be useful in the design of future studies assessing potential disease modifying therapies in patients with multiple system atrophy.

FUNDING

National Institutes of Health, Mayo Clinic Center for Translational Science Activities, and Mayo Funds.