Efficacy and Safety of Xanomeline-Trospium Chloride in Schizophrenia: A Randomized Clinical Trial.

Importance: A significant need exists for new antipsychotic medications with different mechanisms of action, greater efficacy, and better tolerability than existing agents. Xanomeline is a dual M1/M4 preferring muscarinic receptor agonist with no direct D2 dopamine receptor blocking activity. KarXT combines xanomeline with the peripheral muscarinic receptor antagonist trospium chloride with the goal of reducing adverse events due to xanomeline-related peripheral muscarinic receptor activation. In prior trials, xanomeline-trospium chloride was effective in reducing symptoms of psychosis and generally well tolerated in people with schizophrenia. Objective: To evaluate the efficacy and safety of xanomeline-trospium vs placebo in adults with schizophrenia. Design, Setting, and Participants: EMERGENT-3 (NCT04738123) was a phase 3, multicenter, randomized, double-blind, placebo-controlled, 5-week trial of xanomeline-trospium in people with schizophrenia experiencing acute psychosis, conducted between April 1, 2021, and December 7, 2022, at 30 inpatient sites in the US and Ukraine. Data were analyzed from February to June 2023. Interventions: Participants were randomized 1:1 to receive xanomeline-trospium chloride (maximum dose xanomeline 125 mg/trospium 30 mg) or placebo for 5 weeks. Main Outcomes and Measures: The prespecified primary end point was change from baseline to week 5 in Positive and Negative Syndrome Scale (PANSS) total score. Secondary outcome measures were change from baseline to week 5 in PANSS positive subscale score, PANSS negative subscale score, PANSS Marder negative factor score, Clinical Global Impression-Severity score, and proportion of participants with at least a 30% reduction in PANSS total score. Safety and tolerability were also evaluated. Results: A total of 256 participants (mean [SD] age, 43.1 [11.8] years; 191 men [74.6%]; 156 of 256 participants [60.9%] were Black or African American, 98 [38.3%] were White, and 1 [0.4%] was Asian) were randomized (125 in xanomeline-trospium group and 131 in placebo group). At week 5, xanomeline-trospium significantly reduced PANSS total score compared with placebo (xanomeline-trospium , -20.6; placebo, -12.2; least squares mean difference, -8.4; 95% CI, -12.4 to -4.3; P < .001; Cohen d effect size, 0.60). Discontinuation rates due to treatment-emergent adverse events (TEAEs) were similar between the xanomeline-trospium (8 participants [6.4%]) and placebo (7 participants [5.5%]) groups. The most common TEAEs in the xanomeline-trospium vs placebo group were nausea (24 participants [19.2%] vs 2 participants [1.6%]), dyspepsia (20 participants [16.0%] vs 2 participants [1.6%]), vomiting (20 participants [16.0%] vs 1 participant [0.8%]), and constipation (16 participants [12.8%] vs 5 participants [3.9%]). Measures of extrapyramidal symptoms, weight gain, and somnolence were similar between treatment groups. Conclusions and Relevance: Xanomeline-trospium was efficacious and well tolerated in people with schizophrenia experiencing acute psychosis. These findings, together with the previously reported and consistent results from the EMERGENT-1 and EMERGENT-2 trials, support the potential of xanomeline-trospium to be the first in a putative new class of antipsychotic medications without D2 dopamine receptor blocking activity. Trial Registration: ClinicalTrials.gov Identifier: NCT04738123.

Muscarinic Receptor Activators as Novel Treatments for Schizophrenia.

Achieving optimal treatment outcomes for individuals living with schizophrenia remains challenging, despite 70 years of drug development efforts. Many chemically distinct antipsychotics have been developed over the past 7 decades with improved safety and tolerability but with only slight variation in efficacy. All antipsychotics currently approved for the treatment of schizophrenia act as antagonists or partial agonists at the dopamine D2 receptor. With only a few possible exceptions, antipsychotic drugs have similar and modest efficacy for treating positive symptoms and are relatively ineffective in addressing the negative and cognitive symptoms of the disease. The development of novel treatments focused on targeting muscarinic acetylcholine receptors (mAChRs) has been of interest for more than 25 years following reports that treatment with a dual M1/M4-preferring mAChR agonist resulted in antipsychotic-like effects and procognitive properties in individuals living with Alzheimer's disease and schizophrenia; more recent clinical trials have confirmed these findings. In addition, advances in our understanding of the receptor binding and activation properties of xanomeline at specific mAChRs have the potential to inform future drug design targeting mAChRs.

Efficacy and safety of the muscarinic receptor agonist KarXT (xanomeline-trospium) in schizophrenia (EMERGENT-2) in the USA: results from a randomised, double-blind, placebo-controlled, flexible-dose phase 3 trial.

BACKGROUND: New treatments with new mechanisms are urgently needed for people with schizophrenia. Xanomeline is a dual M1 and M4-preferring muscarinic receptor agonist that does not block D2 dopamine receptors, unlike all currently approved treatments for schizophrenia. Xanomeline-trospium (KarXT) combines xanomeline with the peripherally restricted muscarinic receptor antagonist trospium chloride with the goal of ameliorating xanomeline-related adverse events associated with peripheral muscarinic receptors. The EMERGENT-2 trial aimed to assess the efficacy and safety of KarXT in people with schizophrenia experiencing acute psychosis. METHODS: EMERGENT-2 was a randomised, double-blind, placebo-controlled, flexible-dose, 5-week, inpatient, phase 3 trial in people with schizophrenia. Participants were adults aged 18-65 years with a diagnosis of schizophrenia who had a recent worsening of psychosis warranting hospital admission, a Positive and Negative Syndrome Scale (PANSS) score of 80 or higher, and a Clinical Global Impression-Severity score of 4 or higher. The participants were recruited from 22 inpatient sites in the USA, and were randomly assigned (1:1) to KarXT or placebo twice per day. Participants randomly assigned to KarXT received 50 mg xanomeline and 20 mg trospium twice per day for the first 2 days and then 100 mg xanomeline and 20 mg trospium twice per day for days 3-7. Beginning on day 8, KarXT dosing was flexible with an optional increase to 125 mg xanomeline and 30 mg trospium twice per day and the option to return to 100 mg xanomeline and 20 mg trospium based on tolerability. The primary endpoint was change from baseline to week 5 in PANSS total score. Efficacy analyses used the modified intention-to-treat population (all randomly assigned participants who received at least one trial medication dose and had at least one post-baseline PANSS assessment). Least squares mean change from baseline, SE, and least squares mean difference between the KarXT and placebo groups at week 5, along with the 95% CI and two-sided p values were calculated for the primary and secondary continuous efficacy endpoints. Safety analyses included all participants receiving at least one trial medication dose and used descriptive statistics. This trial is registered with ClinicalTrials.gov (NCT04659161). FINDINGS: From Dec 16, 2020, to April 13, 2022, of 407 people who were screened, 252 participants meeting enrolment criteria were randomly assigned to the KarXT (n=126) or placebo (n=126). Baseline PANSS total scores were 98·3 (KarXT; n=126) and 97·9 (placebo; n=125). The trial met the primary endpoint with a mean change from baseline to week 5 in PANSS total score that favoured KarXT (-21·2 points, SE 1·7) versus placebo (-11·6 points, 1·6; least squares mean difference -9·6; 95% CI -13·9 to -5·2; p<0·0001, Cohen's d effect size=0·61). All secondary endpoints were also met, and favoured KarXT versus placebo (p<0·05). The most common adverse events with KarXT versus placebo were constipation (27 [21%] vs 13 [10%]), dyspepsia (24 [19%] vs 10 [8%]), headache (17 [14%] vs 15 [12%]), nausea (24 [19%] vs seven [6%]), vomiting (18 [14%] vs one [1%]), hypertension (12 [10%] vs one [1%]), dizziness (11 [9%] vs four [3%]), gastro-oesophageal reflux disease (eight [6%] vs zero [0%]), and diarrhoea (seven [6%] vs four [3%]). Treatment-emergent adverse event rates of extrapyramidal motor symptoms (KarXT, zero [0%] vs placebo, zero [0%]), akathisia (one [1%] vs one [1%]), weight gain (zero [0%] vs one [1%]), and somnolence (six [5%] vs five [4%]) were similar between the KarXT and placebo groups, as were adverse event-related discontinuation rates (nine [7%] vs seven [6%]). INTERPRETATION: In the EMERGENT-2 trial, KarXT was effective in reducing positive and negative symptoms and was generally well tolerated. These results support the potential for KarXT to represent a new class of effective and well tolerated antipsychotic medicines based on activating muscarinic receptors, not the D2 dopamine receptor-blocking mechanism of all current antipsychotic medications. Results from additional trials, including the identical EMERGENT-3 trial and the 52-week, open-label EMERGENT-4 and EMERGENT-5 trials, will provide additional information on the efficacy and safety of KarXT in people with schizophrenia. FUNDING: Karuna Therapeutics.

Innovative Technologies in CNS Trials: Promises and Pitfalls for Recruitment, Retention, and Representativeness.

Objective: Recruitment of a sufficiently large and representative patient sample and its retention during central nervous system (CNS) trials presents major challenges for study sponsors. Technological advances are reshaping clinical trial operations to meet these challenges, and the COVID-19 pandemic further accelerated this development. Method of Research: The International Society for CNS Clinical Trials and Methodology (ISCTM; www.isctm.org) Innovative Technologies for CNS Trials Working Group surveyed the state of technological innovations for improved recruitment and retention and assessed their promises and pitfalls. Results: Online advertisement and electronic patient registries can enhance recruitment, but challenges with sample representativeness, conversion rates from eligible prescreening to enrolled patients, data privacy and security, and patient identification remain hurdles for optimal use of these technologies. Electronic medical records (EMR) mining with artificial intelligence (AI)/machine learning (ML) methods is promising but awaits translation into trials. During the study treatment phase, technological innovations increasingly support participant retention, including adherence with the investigational treatment. Digital tools for adherence and retention support take many forms, including patient-centric communication channels between researchers and participants, real-time study reminders, and digital behavioral interventions to increase study compliance. However, such tools add technical complexities to trials, and their impact on the generalizability of results are largely unknown. Conclusion: Overall, the group found a scarcity of systematic data directly assessing the impact of technological innovations on study recruitment and retention in CNS trials, even for strategies with already high adoption, such as online recruitment. Given the added complexity and costs associated with most technological innovations, such data is needed to fully harness technologies for CNS trials and drive further adoption.

Evidence of trospium's ability to mitigate cholinergic adverse events related to xanomeline: phase 1 study results.

RATIONALE: The M1/M4 preferring muscarinic receptor agonist xanomeline demonstrated antipsychotic and procognitive effects in patients with Alzheimer's disease or schizophrenia in prior studies, but further clinical development was limited by cholinergic adverse events (AEs). KarXT combines xanomeline with the peripherally restricted muscarinic receptor antagonist trospium with the goal of improving tolerability and is in clinical development for schizophrenia and other neuropsychiatric disorders. OBJECTIVE: Test the hypothesis that trospium can mitigate cholinergic AEs associated with xanomeline. METHODS: Healthy volunteers enrolled in this phase 1 (NCT02831231), single-site, 9-day, double-blind comparison of xanomeline alone (n = 33) versus KarXT (n = 35). Rates of five prespecified cholinergic AEs (nausea, vomiting, diarrhea, excessive sweating, salivary hypersecretion) were compared between treatment arms. Vital signs, electrocardiograms (ECGs), safety laboratory values, and pharmacokinetic (PK) analyses were assessed. A self-administered visual analog scale (VAS) and clinician-administered scales were employed. RESULTS: Compared with xanomeline alone, KarXT reduced composite incidences of the five a priori selected cholinergic AEs by 46% and each individual AE by ≥ 29%. There were no episodes of syncope in KarXT-treated subjects; two cases occurred in the xanomeline-alone arm. The rate of postural dizziness was 11.4% in the KarXT arm versus 27.2% with xanomeline alone. ECG, vital signs, and laboratory values were not meaningfully different between treatment arms. The VAS and clinician-administered scales tended to favor KarXT. PK analysis revealed that trospium did not affect xanomeline's PK profile. CONCLUSIONS: Trospium was effective in mitigating xanomeline-related cholinergic AEs. KarXT had an improved safety profile compared with xanomeline alone.

Safety and tolerability of KarXT (xanomeline-trospium) in a phase 2, randomized, double-blind, placebo-controlled study in patients with schizophrenia.

KarXT combines xanomeline, an M1/M4 preferring muscarinic agonist with no direct D2 receptor antagonism, with the peripherally restricted anticholinergic trospium. In EMERGENT-1 (NCT03697252), a 5-week, randomized, double-blind, placebo-controlled, phase 2 study in inpatients with schizophrenia, KarXT met the primary efficacy endpoint, numerous secondary endpoints, and was generally well tolerated. Here, we conducted additional post hoc analyses of safety and tolerability data of KarXT from EMERGENT-1 with a particular focus on adverse events (AEs) that may be associated with muscarinic receptor agonism (nausea or vomiting) or antagonism (dry mouth or constipation). A total of 179 patients received at least one dose of either KarXT (n = 89) or placebo (n = 90) and were included in the analyses. KarXT was associated with a low overall AE burden. The majority of procholinergic and anticholinergic AEs with KarXT were mild, occurred in the first 1-2 weeks of treatment, and were transient with a median duration ranging from 1 day for vomiting to 13 days for dry mouth. No patients in either treatment group discontinued the study due to any procholinergic or anticholinergic AEs. Incidence of somnolence/sedation AEs with KarXT were low and similar to those in the placebo group. KarXT was associated with no significant or clinically relevant changes in body weight, metabolic parameters, or vital signs. KarXT was generally well tolerated with an AE profile consistent with the activity of xanomeline-trospium at muscarinic receptors.

Effectiveness of KarXT (xanomeline-trospium) for cognitive impairment in schizophrenia: post hoc analyses from a randomised, double-blind, placebo-controlled phase 2 study.

The muscarinic receptor agonist xanomeline improved cognition in phase 2 trials in Alzheimer's disease and schizophrenia. We present data on the effect of KarXT (xanomeline-trospium) on cognition in schizophrenia from the 5-week, randomised, double-blind, placebo-controlled EMERGENT-1 trial (NCT03697252). Analyses included 125 patients with computerised Cogstate Brief Battery (CBB) subtest scores at baseline and endpoint. A post hoc subgroup analysis evaluated the effects of KarXT on cognitive performance in patients with or without clinically meaningful cognitive impairment at baseline, and a separate outlier analysis excluded patients with excessive intraindividual variability (IIV) across cognitive subdomains. ANCOVA models assessed treatment effects for completers and impairment subgroups, with or without removal of outliers. Sample-wide, cognitive improvement was numerically but not statistically greater with KarXT (n = 60) than placebo (n = 65), p = 0.16. However, post hoc analyses showed 65 patients did not exhibit clinically meaningful cognitive impairment at baseline, while eight patients had implausibly high IIV at one or both timepoints. Significant treatment effects were observed after removing outliers (KarXT n = 54, placebo n = 63; p = 0.04). Despite the small sample size, a robust (d = 0.50) and significant effect was observed among patients with cognitive impairment (KarXT n = 23, placebo n = 37; p = 0.03). These effects did not appear to be related to improvement in PANSS total scores (linear regression, R2 = 0.03). Collectively, these findings suggest that KarXT may have a separable and meaningful impact on cognition, particularly among patients with cognitive impairment.

Antipsychotic Efficacy of KarXT (Xanomeline-Trospium): Post Hoc Analysis of Positive and Negative Syndrome Scale Categorical Response Rates, Time Course of Response, and Symptom Domains of Response in a Phase 2 Study.

Objective: To evaluate Positive and Negative Syndrome Scale (PANSS) categorical response rates, time course of response, and symptom subdomains of response with the combination oral agent KarXT (xanomeline-trospium) in the treatment of schizophrenia.Methods: Post hoc analysis was conducted for EMERGENT-1 (NCT03697252), a 5-week, inpatient, placebo-controlled, phase 2 study of acute psychosis in patients who met DSM-5 criteria for schizophrenia. The EMERGENT-1 study was conducted between September 2018 and August 2019. Categorical thresholds of response used were PANSS total score reductions of ≥ 20%, ≥ 30%, ≥ 40%, and ≥ 50% between baseline and study end. Number needed to treat (NNT) for each categorical threshold was calculated. The proportion of KarXT- and placebo-treated patients achieving each response threshold at weeks 2, 4, and 5 was assessed. Marder 5-factor analysis of PANSS assessed response with KarXT across symptom domains.Results: A total of 83 patients in the KarXT group and 87 patients in the placebo group were included in the modified intent-to-treat analysis. Response rates with KarXT ranged from 59.0% for a ≥ 20% threshold to 15.7% for a ≥ 50% threshold. All response rates with KarXT were significantly higher than in the placebo arm (P < .05), with NNTs ranging from 3 (≥ 20% improvement) to 11 (≥ 50% improvement). KarXT was associated with a significantly higher response rate relative to placebo as early as 2 weeks for ≥ 20% (P = .0001) and ≥ 30% (P = .0022) thresholds and at 4 weeks for the ≥ 40% (P = .0049) and ≥ 50% (P = .0041) thresholds. Each of the Marder 5 factors showed significant differences favoring KarXT over placebo (P < .05) by 2 weeks and continuing through week 5 (endpoint Cohen d effect sizes, 0.48-0.66).Conclusions: KarXT provided clinically meaningful responder rates on PANSS total score compared with placebo at each response threshold, providing further support of the successful primary and secondary endpoints. Response was demonstrated as early as 2 weeks relative to placebo. KarXT demonstrated improvements vs placebo in all 5 factors (positive symptoms, negative symptoms, disorganized thought, uncontrolled hostility, and anxiety/depression).Trial Registration: ClinicalTrials.gov identifier: NCT03697252.

The Impact of Aberrant Data Variability on Drug-Placebo Separation and Drug/Placebo Response in an Acute Schizophrenia Clinical Trial.

OBJECTIVE: In the current posthoc analyses, we evaluated the impact of markers of aberrant data variability on drug placebo separation and placebo and drug response in an acute schizophrenia clinical trial. METHODS: Positive and negative syndrome scale data were obtained from a phase 2, randomized, double-blind, placebo controlled trial in hospitalized adults with schizophrenia experiencing an acute exacerbation. We assessed the impact of a total of six markers of aberrant data variability: erratic ratings, unusually large postbaseline improvement, high and low mean square successive difference (MSSD), identical and nearly identical ratings and compared the drug placebo difference, drug and treatment response at last visit in affected subjects vs those not affected. All analyses were conducted using generalized linear models. RESULTS: In this posthoc analysis, drug placebo separation decreased with the presence of most markers of aberrant data variability. The only exception was high MSSD was associated with significant increase in the signal. In the affected subjects, the presence of indicators of increased data variability augmented the response to placebo, in the case of large postbaseline change and high MSSD, significantly. The presence of indicators of decreased variability numerically but not statistically decreased the response to placebo. Similar findings were observed in the drug treatment group with the exception of erratic ratings that numerically but not statistically decreased the response to the drug. DISCUSSION: The presence of most indicators of aberrant data variability had a detrimental effect on drug-placebo separation and showed different effects on placebo and treatment response.

Site-independent confirmation of primary site-based PANSS ratings in a schizophrenia trial.

Blinded, site-independent (remote) ratings from audio-digital recordings of site-based Positive and Negative Syndrome Scale (PANSS) interviews were obtained in a 5-week, randomized, double-blinded study assessing the safety, tolerability, and efficacy of KarXT (a fixed combination of xanomeline and trospium chloride) in hospitalized adults with schizophrenia experiencing an acute exacerbation of psychosis (EMERGENT-1; ClinicalTrials.gov identifier: NCT3697252). The blinded site-independent raters had no knowledge of site location, study visit, drug vs. placebo assignment, or any treatment emergent adverse events (TEAEs). Concordance analyses of 561 paired site-based and site-independent PANSS ratings across all visits revealed a high correlation (ICC = 0.775). Paired scoring differences were positively correlated with the PANSS total score (Spearman's rho = 0.37, p < 0.0001). Paired PANSS scores were available from 148 subjects at both the baseline and end of study visits (KarXT = 72, Placebo = 76). Site-based PANSS total scores (primary aim) revealed a significantly greater improvement from baseline in the KarXT group compared to the placebo group (p < 0.0001). The blinded site-independent PANSS total scores derived from listening to and scoring the recorded site-based PANSS interviews replicated this finding (p < 0.001) and yielded an overall predictive value of 85.1% for matching the site-based response/non-response outcomes. TEAE's have the potential to "unblind" site-based ratings. In this study, the site-independent raters were blinded to TEAEs, affirmed the site-based PANSS ratings, and mitigated concerns about possible functional unblinding of site-based raters. This method of blinded assessment via audio-digital recordings may have utility for other studies concerned with ratings precision and/or functional unblinding.

Muscarinic Cholinergic Receptor Agonist and Peripheral Antagonist for Schizophrenia.

BACKGROUND: The muscarinic receptor agonist xanomeline has antipsychotic properties and is devoid of dopamine receptor-blocking activity but causes cholinergic adverse events. Trospium is a peripherally restricted muscarinic receptor antagonist that reduces peripheral cholinergic effects of xanomeline. The efficacy and safety of combined xanomeline and trospium in patients with schizophrenia are unknown. METHODS: In this double-blind, phase 2 trial, we randomly assigned patients with schizophrenia in a 1:1 ratio to receive twice-daily xanomeline-trospium (increased to a maximum of 125 mg of xanomeline and 30 mg of trospium per dose) or placebo for 5 weeks. The primary end point was the change from baseline to week 5 in the total score on the Positive and Negative Syndrome Scale (PANSS; range, 30 to 210, with higher scores indicating more severe symptoms of schizophrenia). Secondary end points were the change in the PANSS positive symptom subscore, the score on the Clinical Global Impression-Severity (CGI-S) scale (range, 1 to 7, with higher scores indicating greater severity of illness), the change in the PANSS negative symptom subscore, the change in the PANSS Marder negative symptom subscore, and the percentage of patients with a response according to a CGI-S score of 1 or 2. RESULTS: A total of 182 patients were enrolled, with 90 assigned to receive xanomeline-trospium and 92 to receive placebo. The PANSS total score at baseline was 97.7 in the xanomeline-trospium group and 96.6 in the placebo group. The change from baseline to week 5 was -17.4 points with xanomeline-trospium and -5.9 points with placebo (least-squares mean difference, -11.6 points; 95% confidence interval, -16.1 to -7.1; P<0.001). The results for the secondary end points were significantly better in the xanomeline-trospium group than in the placebo group, with the exception of the percentage of patients with a CGI-S response. The most common adverse events in the xanomeline-trospium group were constipation, nausea, dry mouth, dyspepsia, and vomiting. The incidences of somnolence, weight gain, restlessness, and extrapyramidal symptoms were similar in the two groups. CONCLUSIONS: In a 5-week trial, xanomeline-trospium resulted in a greater decrease in the PANSS total score than placebo but was associated with cholinergic and anticholinergic adverse events. Larger and longer trials are required to determine the efficacy and safety of xanomeline-trospium in patients with schizophrenia. (Funded by Karuna Therapeutics and the Wellcome Trust; ClinicalTrials.gov number, NCT03697252.).

The TOMMORROW study: Design of an Alzheimer's disease delay-of-onset clinical trial.

INTRODUCTION: Alzheimer's disease (AD) is a continuum with neuropathologies manifesting years before clinical symptoms; thus, AD research is attempting to identify more disease-modifying approaches to test treatments administered before full disease expression. Designing such trials in cognitively normal elderly individuals poses unique challenges. METHODS: The TOMMORROW study was a phase 3 double-blind, parallel-group study designed to support qualification of a novel genetic biomarker risk assignment algorithm (BRAA) and to assess efficacy and safety of low-dose pioglitazone to delay onset of mild cognitive impairment due to AD. Eligible participants were stratified based on the BRAA (using TOMM40 rs 10524523 genotype, Apolipoprotein E genotype, and age), with high-risk individuals receiving low-dose pioglitazone or placebo and low-risk individuals receiving placebo. The primary endpoint was time to the event of mild cognitive impairment due to AD. The primary objectives were to compare the primary endpoint between high- and low-risk placebo groups (for BRAA qualification) and between high-risk pioglitazone and high-risk placebo groups (for pioglitazone efficacy). Approximately 300 individuals were also asked to participate in a volumetric magnetic resonance imaging substudy at selected sites. RESULTS: The focus of this paper is on the design of the study; study results will be presented in a separate paper. DISCUSSION: The design of the TOMMORROW study addressed many key challenges to conducting a dual-objective phase 3 pivotal AD clinical trial in presymptomatic individuals. Experiences from planning and executing the TOMMORROW study may benefit future AD prevention/delay-of-onset trials.

Effects of pioglitazone on mnemonic hippocampal function: A blood oxygen level-dependent functional magnetic resonance imaging study in elderly adults.

INTRODUCTION: Mitochondrial dysfunction is implicated in the pathophysiology of Alzheimer's disease (AD). Accordingly, drugs that positively influence mitochondrial function are being evaluated in delay-of-onset clinical trials with at-risk individuals. Such ongoing clinical research can be advanced by developing a better understanding of how these drugs affect intermediate brain phenotypes associated with both AD risk and pathophysiology. METHODS: Using a randomized, parallel-group, placebo-controlled design in 55 healthy elderly volunteers, we explored the effects of oral, low-dose pioglitazone, a thiazolidinedione with promitochondrial effects, on hippocampal activity measured with functional magnetic resonance imaging during the encoding of novel face-name pairs. RESULTS: Compared with placebo, 0.6 mg of pioglitazone (but not 2.1 mg, 3.9 mg, or 6.0 mg) administered daily for 14 days was associated with significant increases in right hippocampal activation during encoding of novel face-name pairs at day 7 and day 14, relative to baseline. DISCUSSION: Our exploratory analyses suggest that low-dose pioglitazone has measurable effects on mnemonic brain function associated with AD risk and pathophysiology.

A call for comparative effectiveness research to learn whether routine clinical care decisions can protect from dementia and cognitive decline.

Common diseases like diabetes, hypertension, and atrial fibrillation are probable risk factors for dementia, suggesting that their treatments may influence the risk and rate of cognitive and functional decline. Moreover, specific therapies and medications may affect long-term brain health through mechanisms that are independent of their primary indication. While surgery, benzodiazepines, and anti-cholinergic drugs may accelerate decline or even raise the risk of dementia, other medications act directly on the brain to potentially slow the pathology that underlies Alzheimer's and other dementia. In other words, the functional and cognitive decline in vulnerable patients may be influenced by the choice of treatments for other medical conditions. Despite the importance of these questions, very little research is available. The Alzheimer's Drug Discovery Foundation convened an advisory panel to discuss the existing evidence and to recommend strategies to accelerate the development of comparative effectiveness research on how choices in the clinical care of common chronic diseases may protect from cognitive decline and dementia.

Lessons Learned and Potentials for Improvement in CNS Drug Development: ISCTM Section on Designing the Right Series of Experiments.

Once a molecule has been characterized as engaging an identified target at the appropriate location (affinity and potency), the next step involves designing experiments that will determine its pharmacodynamic activities both for efficacy (on target) and safety-tolerability (on/off target). Two expert presentations focused on looking back at completed programs and two concentrated on looking forward at ongoing programs. Specific discussions pertain to assessment of pharmacologic agonists (mGluR2/3, k-opiate, peroxisome proliferator-activated receptor gamma) and antagonists (orexin and cannabinoid) in disorders of cognition, mood, and anxiety. Advanced experimental study designs using genetics to guide a treatment trial in Alzheimer's disease and neural target-based approaches as the primary outcome measure in the National Institute of Mental Health-sponsored Fast-Fail Trials (FAST)-Mood and Anxiety Spectrum Disorders (MAS) initiative for depression showcases novel methodological approaches. Of interest, some of these initiatives were successful, while others were not, and two are currently ongoing. In conclusion, methodologies that were utilized and are currently employed to reach a successful clinical drug trial outcome are appreciated, and in case of failure, approaches to reviewing programs to enable learning that would be helpful to future programs are brought forth. This article is based on proceedings from the "Designing the Right Series of Experiments" session, which was held during the International Society for Clinical Trials Meeting (ISCTM) in Philadelphia, Pennsylvania, September 30 to October 2, 2013.

Assessing cognition and function in Alzheimer's disease clinical trials: do we have the right tools?

Several lines of evidence from Alzheimer's disease (AD) research continue to support the notion that the biological changes associated with AD are occurring possibly several decades before an individual will experience the cognitive and functional changes associated with the disease. The National Institute on Aging-Alzheimer's Association revised criteria for AD provided a framework for this new thinking. As a result of this growing understanding, several research efforts have launched or will be launching large secondary prevention trials in AD. These and other efforts have clearly demonstrated a need for better measures of cognitive and functional change in people with the earliest changes associated with AD. Recent draft guidance from the US Food and Drug Administration further elevated the importance of cognitive and functional assessments in early stage clinical trials by proposing that even in the pre-symptomatic stages of the disease, approval will be contingent on demonstrating clinical meaningfulness. The Alzheimer's Association's Research Roundtable addressed these issues at its fall meeting October 28-29, 2013, in Washington, D.C. The focus of the discussion included the need for improved cognitive and functional outcome measures for clinical of participants with preclinical AD and those diagnosed with Mild Cognitive Impairment due to AD.

New applications of disease genetics and pharmacogenetics to drug development.

TOMMORROW is a Phase III delay of onset clinical trial to determine whether low doses of pioglitazone, a molecule that induces mitochondrial doubling, delays the onset of MCI-AD in normal subjects treated with low dose compared to placebo. BOLD imaging studies in rodents and man were used to find the dose that increases oxygen consumption at central regions of the brain in higher proportion than activation of large corticol regions. The trial is made practical by the use of a pharmacogenetic algorithm based on TOMM40 and APOE genotypes and age to identify normal subjects at high risk of MCI-AD between the ages of 65-83 years within a five year follow-up period.

Safety and tolerability of rivastigmine capsule with memantine in patients with probable Alzheimer's disease: a 26-week, open-label, prospective trial (Study ENA713B US32).

OBJECTIVE: Rivastigmine, a dual cholinesterase inhibitor (ChEI), is widely approved for the symptomatic treatment of both mild-to-moderate Alzheimer's disease (AD) and Parkinson's disease dementia. Orally administered ChEIs may be associated with gastrointestinal (GI) side effects and add-on therapy with memantine, an N-methyl-d-aspartate receptor antagonist, approved for moderate-to-severe AD, may ameliorate such side effects. This was a 26-week, prospective, multicenter, single-arm, open-label pilot study to assess the safety and tolerability of rivastigmine capsules plus memantine in patients with moderate AD. METHODS: The primary objective was to assess the safety and tolerability of rivastigmine capsules 6-12 mg/day plus memantine (5-20 mg/day) as measured by the incidences of vomiting and nausea compared with those reported in the rivastigmine United States Prescribing Information (US PI). A total of 117 patients were enrolled with 116 receiving at least one dose of study medication. RESULTS: The incidences of nausea and vomiting (30% and 13%, respectively) observed in patients who received 6-12 mg/day rivastigmine plus memantine were lower than those stated in the US PI for rivastigmine monotherapy 6-12 mg/day (47% and 31%, respectively). The most common adverse events were nausea, vomiting, and dizziness. CONCLUSION: Results from this study suggest the combination of rivastigmine capsule and memantine in patients with moderate AD is safe and tolerable. A greater reduction in the GI tolerability of rivastigmine has been established with rivastigmine transdermal patch.

Switching from donepezil tablets to rivastigmine transdermal patch in Alzheimer's disease.

OBJECTIVE: Evaluate safety and tolerability of switching from donepezil to rivastigmine transdermal patch in patients with mild to moderate Alzheimer's disease. METHODS: Prospective, parallel-group, open-label study to evaluate immediate or delayed switch from 5-10 mg/day donepezil to 4.6 mg/24 h rivastigmine following a 4-week treatment period. RESULTS: Rates of discontinuation due to any reason or adverse events were similar between groups. Incidences of gastrointestinal adverse events were 3.8% in the immediate and 0.8% in the delayed switch group. No patients discontinued secondary to nausea and vomiting. Discontinuations due to application site reactions were low (2.3%). Asymptomatic bradycardia was more common following the immediate switch (2.3% vs 0%); however, these patients had coexisting cardiac comorbidities. CONCLUSION: Both switch strategies were safe and well tolerated. The majority of patients may be able to switch directly to rivastigmine patches without a withdrawal period. Appropriate clinical judgment should be used for patients with existing bradycardia or receiving beta blockers.