Safety and tolerability of CI-979 in patients with Alzheimer's disease

Exploratory Biomarker Study of the Triple Reuptake Inhibitor SEP-432 Compared to the Dual Reuptake Inhibitor Duloxetine in Healthy Normal Subjects

INTRODUCTION

SEP-432 is a triple monoamine reuptake inhibitor of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), based on in vitro binding studies. We sought evidence that SEP-432 engages these monoamine systems by measuring concentrations of monoamines and/or their main metabolites in cerebrospinal fluid (CSF) and plasma and comparing results to duloxetine, a dual reuptake inhibitor of NE and 5-HT.

METHODS

Eighteen healthy normal subjects received either SEP-432 (300 mg/day), duloxetine (60 mg/day), or placebo for 14 days in-clinic (double blind) with CSF and plasma collections at baseline (single lumbar puncture) and Day 14 (24-h CSF and plasma collection). Concentrations of monoamines and their metabolites, as well as pharmacokinetic concentrations of SEP-432 and metabolite, were quantified by liquid chromatography-tandem mass spectrometry.

RESULTS

Compared to placebo in the Day 14 area under the curve 24-h (AUC0-24 h ) analysis, SEP-432 significantly (P < 0.05) decreased the NE metabolite dihydroxyphenylglycol (DHPG) in CSF and plasma, decreased 5-HT in plasma, and did not affect DA metabolites, while duloxetine had significant effects on DHPG and 5-HT. Time-matched baseline to Day 14 biomarker comparisons confirmed these findings.

CONCLUSION

CSF monoamine biomarkers confirmed central NET activity for SEP-432 and duloxetine's dual reuptake inhibition.

A memory and organizational aid improves Alzheimer disease research consent capacity: results of a randomized, controlled trial

OBJECTIVES

Early and progressive cognitive impairments of patients with Alzheimer disease (AD) hinder their capacity to provide informed consent. Unfortunately, the limited research on techniques to improve capacity has shown mixed results. Therefore, the authors tested whether a memory and organizational aid improves the performance of patients with AD on measures of capacity and competency to give informed consent.

DESIGN, SETTING, AND PARTICIPANTS

Patients with AD randomly assigned to standard consent or standard plus a memory and organizational aid.

INTERVENTION

Memory and organizational aid summarized the content of information mandated under the informed consent disclosure requirements of the Common Rule at a sixth grade reading level.

MEASUREMENTS

Three psychiatrists without access to patient data independently reviewed MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR) interview transcripts to judge whether the patient was capable of providing informed consent. The agreement of at least two of the three experts defined a participant as capable of providing informed consent. Secondary outcomes are MacCAT-CR measures of understanding, appreciation and reasoning, and comparison with cognitively normal older adult norms.

RESULTS

AD intervention and control groups were similar in terms of age, education, and cognitive status. The intervention group was more likely to be judged competent than control group and had higher scores on MacCAT-CR measure of understanding. The intervention had no effect on the measures of appreciation or reasoning.

CONCLUSIONS

A consent process that addresses the deficits in memory and attention of a patient with AD can improve capacity to give informed consent for early phase AD research. The results also validate the MacCAT-CR as an instrument to measure capacity, especially the understanding subscale.

TRIAL REGISTRY

ClinicalTrials.Gov#NCT00105612, http://clinicaltrials.gov/show/NCT00105612.

A novel derivative of xanomeline improves fear cognition in aged mice

The M1/M4 muscarinic acetylcholine receptor agonist xanomeline can significantly improve the cognitive function, but the intolerable side effects limit its clinical usefulness. Our recent study has reported a novel derivative of xanomeline, 3-[3-(3-(3-florophenyl)-2-propyn-1-ylthio)-1,2,5-thiadiazol-4-yl]-1,2,5,6-tetrahydro-1-methylpyridine oxalate (EUK1001), exhibited higher affinity of mAChRs and less side effects relative to xanomeline. In the present study, we further utilized behavioral and electrophysiological techniques to investigate the effects of EUK1001 on fear cognition and hippocampal long-term potentiation (LTP) in aged mice. Behavioral testing showed that 0.1, 0.5 or 1.0mg/kg EUK1001 group, like 1.0mg/kg xanomeline group, exhibited better performance in contextual fear conditioning and passive avoidance test than vehicle-controls. In the cued fear conditioning test, just 0.5 or 1.0, but not 0.1mg/kg EUK1001, significantly enhanced the levels of freezing response. In addition, theta-burst stimulation (TBS) induced the significant larger hippocampal LTP in brain slices perfused with artificial cerebrospinal fluid (ACSF) containing 0.01microM EUK1001 or in brain slices from aged mice injected intraperitoneally (i.p.) with EUK1001. This enhancing effect was blocked by 0.25microM pirenzepine, a selective M1 antagonist. Together, these results show that EUK1001 can enhance fear cognition and synaptic plasticity via the activation of M1 muscarinic acetylcholine receptors. Thus, EUK1001 may possibly represent a promising lead compound for the treatment of Alzheimer's disease and age-related cognitive deficits.

A novel derivative of xanomeline improved memory function in aged mice

OBJECTIVE

To characterize the function of a new xanomeline-derived M1 agonist, 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1,2,5-thiadiazol-4-yl]-1,2,5,6- tetrahydro-1-methylpyridine Oxalate (EUK1001), the acute toxicity and the effects on synaptic plasticity and cognition of EUK1001 were evaluated.

METHODS

To examine the median lethal dose (LD50) of EUK1001, a wide dose range of EUK1001 was administered by p.o. and i.p. in aged mice. Furthermore, novel object recognition task and in vitro electrophysiological technique were utilized to investigate the effects of EUK1001 on recognition memory and hippocampal synaptic plasticity in aged mice.

RESULTS

EUK1001 exhibited lower toxicity than xanomeline, and improved the performance of aged mice in the novel object recognition test. In addition, bath application of 1 micromol/L EUK1001 directly induced long-term potentiation in the hippocampus slices.

CONCLUSION

We conclude that EUK1001 can improve the age-related cognitive deficits.

Alzheimer's disease patients' and caregivers' capacity, competency, and reasons to enroll in an early-phase Alzheimer's disease clinical trial

OBJECTIVES

To examine the capacity, competency, and reasons for enrolling of patients with Alzheimer's disease (AD) and of their caregivers in an early phase AD clinical trial.

DESIGN

Interviews were conducted with patients with AD, nondemented older persons, and caregivers.

SETTING

Participants' homes.

PARTICIPANTS

Fifteen patients with mild to moderate AD, 15 age- and education-matched nondemented older persons, and 15 patient caregivers.

MEASUREMENTS

Capacity was measured using the MacArthur Competency Assessment Tool for Clinical Research (MacCAT-CR); a study coordinator who reviewed audiotapes of the capacity interviews judged competency, and the reasons for a decision were determined by coding the capacity interviews.

RESULTS

On all measures except the ability to make a choice, patients performed worse than controls (understanding: z = 3.2, P =.001; appreciation: z = 2.8, P =.005; reasoning: z = 3.5, P =.0005), and caregivers (understanding: z = 3.8, P =.0002; appreciation: z = 3.0, P =.003; reasoning: z = 3.6, P =.0003). Using the controls' performance to set psychometric criteria to define capacity, the proportions of patients with adequate understanding, appreciation, and reasoning were six of 15 (40%), three of 15 (20%), and five of 15 (33%). All caregivers and nine of the 15 (60%) patients were competent. Reasons for enrolling typically featured the potential benefit to the patients' health or well-being and altruism that was expressed as a desire to help other patients and their families or a desire to contribute to scientific knowledge.

CONCLUSIONS

The MacCAT-CR, in particular its understanding scale, is a reliable and valid way to assess patient capacity and competency to enroll in an early-phase clinical trial. Although many patients have significant impairments in their capacity, some mild-stage patients are competent. Reasons for enrolling in an early-phase trial blend an expectation of therapeutic benefit and a desire to help others.

Generalised anxiety disorder: treatment options

In recent years generalised anxiety disorder (GAD) has become a much better defined disorder, with specific criteria distinguishing it from the other anxiety disorders; however, it still lacks the same public and scientific interests as some of the other anxiety disorders such as panic and social phobia. Nevertheless, refinement in the treatment of GAD is becoming more evident through the conduct of clinical trials. Up until the mid-1980's, treatment consisted primarily of benzodiazepines. However, as a result of growing characterisation of their abuse potential, other therapeutic options were explored. Benzodiazepines became seen as an effective short-term therapy, and buspirone and some of the newer antidepressants have become the treatment of choice for patients with GAD requiring long-term treatment. Buspirone was the first available alternative to the benzodiazepines in the US; however, the initial excitement over this agent was somewhat dampened because of its mild efficacy combined with a slow onset of action. The antidepressants were seen as beneficial for the treatment of GAD because of the high comorbidity with depression, thus allowing a better outcome for these patients. The antidepressants that offer both a good adverse effect profile and efficacy are the selective serotonin reuptake inhibitors including paroxetine, and the serotonin-norepinephrine reuptake inhibitors such as venlafaxine. Clinicians should also consider the potential benefits of psychotherapy as an adjunct to medication. There are a number of potentially new pharmacotherapies being investigated, including newer serotonin 5-HT1A receptor agonists, cholecystokinin receptor antagonists, neurokinin receptor antagonists, gabapentin and its analogues, and gamma-aminobutyric acid (GABA)A receptor modulators. However, these compounds are all in the early stages of investigation, and there are no new therapies expected to be released in the near future. Nonetheless, in the search for the ideal anxiolytic, a more positive outlook is allowed by imminent future research for new treatment options in patients with GAD.

Ongoing trials in Alzheimer's disease

Researchers have sought to understand the underlying pathophysiology of Alzheimer's disease (AD) ever since Dr A Alzheimer first described the condition in 1907. Unfortunately however, until recently, they have done so with limited success. This lack of clarity has deterred advancements in therapeutic drug research beyond all but the purely symptomatic treatment relief currently available. However, through spatio-temporal analysis of the two types of cerebral lesions that characterise the disorder (senile plaques and neurofibrillary tangles) and the compilation of genetic data concerning familial AD, there now exists the foundation for a more comprehensive understanding of the disease. Although symptomatic cholinergic strategies have beneficial effects, their benefits are modest and current research has turned to the development of other promising strategies, including oestrogen replacement, anti-inflammatory agents, free radical scavengers, anti-oxidants and monoamine oxidase-B (MAO-B) inhibitors. Many of these strategies may have some merit, however further analysis and structured research are necessary before a definitive decision can be made about their efficacy and possible role in AD therapy. Strategies that are directed at halting the underlying biochemical changes in AD are nearing clinical testing and offer the promise for meaningful therapeutic outcomes.

Recent developments in the drug treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder with an impact on public health which continues to increase with the increasing longevity of the population. The disease is characterised clinically by a progressive loss of cognitive and behavioural function. These deficits are thought to result from decreased cholinergic transmission; therefore, restoring cholinergic function has been the main focus in the development of drugs for AD. Several pharmacological approaches to enhancing cholinergic function have been developed for symptomatic or palliative therapy of AD. Although these strategies have resulted in modest cognitive and behavioural improvements in patients with AD, they do not address the underlying progression of the disease. New strategies will be required to slow, stop or reverse the effects of neurodegeneration in AD. A number of potential therapies are currently under investigation, including estrogen replacement, anti-inflammatory agents, free radical scavengers and antioxidants, and monoamine oxidase-B (MAO-B) inhibitors. The evidence for a protective effect of estrogens or nonsteroidal anti-inflammatory drugs (NSAIDs) is controversial, and largely based on retrospective studies. More controlled prospective studies are needed to definitively demonstrate the benefits of long term estrogen or NSAID use in the prevention of AD. Free radical scavengers/antioxidants such as idebenone, and selective prevention MAO-B inhibitors such as lazabemide are well tolerated, but require additional studies in order to demonstrate preventative effects. In addition, other approaches, such as anti-amyloid treatments that affect beta-amylase secretion, aggregation and toxicity, appear promising; treatments that hinder neurofibrillary tangle construction and nerve growth factor (NGF) induction are in the very early stages of development.

Xanomeline compared to other muscarinic agents on stimulation of phosphoinositide hydrolysis in vivo and other cholinomimetic effects

Activation of muscarinic m1 receptors which are coupled to the phosphoinositide (PI) second messenger transduction system is the initial objective of cholinergic replacement therapy in Alzheimer's disease. Thus, we evaluated the ability of the selective muscarinic receptor agonist (SMRA) xanomeline to stimulate in vivo phosphoinositide (PI) hydrolysis and compared it to a number of direct acting muscarinic agonists, two cholinesterase inhibitors and a putative m1 agonist/muscarinic m2 antagonist. Using a radiometric technique, it was determined that administration of xanomeline robustly stimulated in vivo PI hydrolysis and the effect was blocked by muscarinic antagonists, demonstrating mediation by muscarinic receptors. The non-selective muscarinic agonists pilocarpine, oxotremorine, RS-86, S-aceclidine, but not the less active isomer R-aceclidine, also effectively stimulated PI hydrolysis in mice. Amongst the putative m1 agonists, thiopilocarpine, hexylthio-TZTP as well as xanomeline effectively stimulated PI hydrolysis, but milameline, WAL 2014, SKB 202026 and PD 142505 did not significantly alter PI hydrolysis. Furthermore, WAL 2014 and SKB 202026 inhibited agonist-induced PI stimulation, suggesting that they act as antagonists at PI-coupled receptors in vivo. The cholinesterase inhibitors, tacrine and physostigmine, and the mixed muscarinic m1 agonist/m2 antagonist LU25-109 did not activate in vivo PI hydrolysis. Xanomeline, hexylthio-TZTP and thiopilocarpine were relatively free of cholinergic side effects, whereas milameline, WAL 2014 and SKB 202026 produced non-selective effects. Therefore, these data demonstrate that xanomeline selectively activates in vivo PI hydrolysis, consistent with activation of biochemical processes involved in memory and cognition and xanomeline's beneficial clinical effects on cognition in Alzheimers patients.

Safety and tolerability of metrifonate in patients with Alzheimer's disease: results of a maximum tolerated dose study

Metrifonate, a pro-drug that is transformed non-enzymatically into a potent inhibitor of acetylcholinesterase (AChE), has been used in the tropics for over 30 years for the treatment of schistosomiasis. A pilot study, and Phase I and Phase II studies of metrifonate in Alzheimer's disease (AD) patients conducted prior to the current study showed benign, dose-dependent adverse event profiles consisting primarily of gastrointestinal events, optimal daily dosing with a loading phase (in the absence of a loading dose phase, 6-8 weeks were required to attain steady-state AChE inhibition levels), and an improvement in Alzheimer's Disease Assessment Scale (ADAS) scores. The current open-label study was designed to evaluate the safety and tolerability of relatively high loading doses, followed by lower maintenance doses of metrifonate in the same patient population, and to determine the maximum tolerated dose (MTD) of metrifonate. Accordingly, the first cohort of 8 probable AD patients (per National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association [NINCDS-ADRDA] criteria) were administered once-daily loading doses of 2.5 mg/kg (125-225 mg) for 14 days, followed by 4.0 mg/kg (200-360 mg) for an additional 3 days. These patients were maintained on once-daily doses of 2.0 mg/kg (100-180 mg) for 14 days. AChE inhibition for this cohort ranged from 88% to 94%. On Day 28 of 31, this cohort was discontinued due to moderate to severe side effects in 6 patients; consequently, the second cohort of 8 probable AD patients received a once-daily loading dose of 2.5 mg/kg (125-225 mg) for 14 days followed by a once-daily maintenance dose of 1.5 mg/kg (75-135 mg) for 35 days. This maintenance dose yielded an AChE inhibition level ranging from 89% to 91%. In spite of an AChE inhibition level comparable to that achieved with the higher dose, the reduced dose was associated with a more favorable adverse event profile which was mainly gastrointestinal and musculoskeletal in nature. The maximum tolerated dose was established at 1.5 mg/kg/day (75-135 mg/day) for maintenance dosing in AD patients.

The profile of sabcomeline (SB-202026), a functionally selective M1 receptor partial agonist, in the marmoset

1. Sabcomeline (SB-202026, 0.03 mg kg(-1), p.o.), a potent and functionally selective M1 receptor partial agonist, caused a statistically significant improvement in the performance of a visual object discrimination task by marmosets. No such improvement was seen after RS86 (0.1 mg kg(-1), p.o.). 2. Initial learning, which only required an association of object with reward and an appropriate response to be made, was not significantly affected. Reversal learning, which required both the extinction of the previously learned response and the acquisition of a new response strategy, was significantly improved after administration of sabcomeline (0.03 mg kg(-1), p.o.). 3. Sabcomeline (0.03 and 0.1 mg kg(-1), p.o.) had no significant effect on mean blood pressure measured for 2 h after administration in the conscious marmoset. 4. Sabcomeline (0.03 mg kg(-1), p.o.) caused none of the overt effects such as emesis or behaviours often seen after the administration of muscarinic agonists, e.g. face rubbing and licking. 5. This is the first study to demonstrate cognitive enhancement by a functionally selective M1 receptor partial agonist in a normal (i.e. non-cognitively impaired) non-human primate and this effect was seen at a dose which did not cause side effects. 6. Perseverative behaviour and deficient acquisition of new information are seen in patients with Alzheimer's disease (AD). Therefore the data suggest that sabcomeline might be of therapeutic benefit in the treatment of AD.

A bridging study of LU 25-109 in patients with probable Alzheimer's disease

Lu 25-109 is a functionally selective partial M1 agonist with M2/M3 antagonist properties. This double-blind, placebo-controlled, two-part, inpatient bridging study was designed to evaluate the safety and tolerability of multiple oral doses of Lu 25-109 in patients with Alzheimer's Disease(AD), and to determine the maximum tolerated dose (MTD) in this population. In the first part of the study, the fixed-dose MTD was to be determined in five consecutive panels of 6 patients each (4 Lu 25-109/2 placebo). Doses for the five panels were 100, 125, 150, 200, and 225 mg tid for 7 days. Cholinergic adverse events such as increased salivation, dizziness, and gastrointestinal symptoms were observed at all doses studied. The dosing of fixed-dose panels was discontinued after 3 days at 200 mg tid due to unacceptable gastrointestinal adverse events. Thus, 150 mg tid was defined as the fixed-dose MTD. The second part of the study, conducted in a single panel of 8 patients (6 Lu 25-109/2 placebo), was designed to determine if patients could tolerate higher doses of Lu 25-109 when administered on a titration regimen. Patients were to receive doses that were 50%, 75%, 100%, 125%, and 150% of the fixed dose MTD, with dose increases every five days. The first dose, 75 mg tid, was very well-tolerated; however, as in the first phase of the study, patients did not tolerate the 200 mg tid dose. Thus, the titration regimen employed did not improve the overall tolerability of Lu 25-109.

Establishing the maximum tolerated dose of lesopitron in patients with generalized anxiety disorder: a bridging study

Lesopitron, a 5-hydroxytryptamine 1A agonist, is a new potential anxiolytic of the azapirone class. It has greater potency in animal models of anxiety than buspirone, gepirone, or ipsapirone, and it lacks the antidopaminergic effects associated with buspirone. Lesopitron has been tolerated at single doses up to 50 mg and repeated dosages of 45 mg/day in healthy volunteers. Forty-two patients with generalized anxiety disorder (GAD) were enrolled in this double-blind bridging study to determine the safety and tolerability of fixed doses of lesopitron (20, 25, 30, 40, 45, 50, and 60 mg two times a day) over a 6 1/2-day inpatient administration period. Each of the seven panels included six patients (four drug/two placebo). One patient in the 25-mg, two-times-a-day panel voluntarily withdrew because of increased anxiety symptoms. One patient experienced severe orthostatic hypotension at 60 mg two times a day, and moderate to severe adverse events (dizziness, lightheadedness, nausea, headache) occurred in two other patients at this dosage. The most commonly reported adverse events in all the panels were headache, dizziness, and nausea. Lesopitron is rapidly absorbed in patients, having a time to maximum concentration (Tmax) ranging from 0.5 to 1 hour, and its elimination half-life ranged from 1.1 to 5.6 hours. Peak plasma concentrations showed high interindividual variability for lesopitron, but increased linearly with dose for the main metabolite, 5-hydroxylesopitron. We defined the maximum tolerated dose in GAD patients as 50 mg two times a day, twice as high as the highest dose tested in healthy volunteers.

Safety/tolerability trial of SDZ ENA 713 in patients with probable Alzheimer's disease

SDZ ENA 713 (ENA 713) is an acetylcholinesterase inhibitor being developed as a potential treatment for Alzheimer's disease (AD). A prior Phase II safety and efficacy study used an upper dose limit of 6 mg/day ENA 713. The present study was designed to assess the safety and tolerability of higher doses of ENA 713 in probable AD patients. Fifty AD patients (22M; 28F, mean age 68 yrs, range 45-90) were assigned to a fixed, nine-week dose escalation schedule in which they were randomized to receive up to 12 mg/day of ENA 713 bid (n=20) or tid (n=20), or placebo (n=10) followed by a one-week washout. Mg/day dose escalation for the bid and tid ENA 713 groups was identical, beginning with 2 mg/day on Days 1 to 3 and escalating to 12 mg/day in Weeks 8 and 9. Doses through 12 mg/day were well tolerated. Most adverse events were mild to moderate in severity and of limited duration, most commonly headache, nausea, dizziness, and diarrhea. Three of forty patients on ENA 713 discontinued, all due to adverse events. Two experienced nausea and vomiting; the third experienced an unrelated mild atrial fibrillation.

Scientific and ethical concerns in clinical trials in Alzheimer's patients: the bridging study

This paper reviews the scientific and ethical issues surrounding the conduct of bridging studies in patients with Alzheimer's disease (AD). Bridging studies, so called because they facilitate the transition from phase I to phase II development, are late phase I safety/tolerance studies which determine the maximum tolerated dose (MTD) in patients before initiating phase II efficacy studies. Determining the MTD in patients is important because we have found that AD patients appear to respond to cholinergic compounds differently from normal volunteers, reaching a different MTD. Preliminary evidence of dose-related efficacy with two cholinergic compounds lends support to our contention that determination of the highest tolerated dose maximizes the potential to detect efficacy. We will review the early clinical development of several cholinergic compounds and make recommendations for the design and conduct of bridging studies based on our experience. A fixed-dose panel design with dosages based on the MTD determined in normal volunteers is recommended. In order to minimize risk to the patients, ensuring that scientific benefits outweigh the risks, a bridging study must be supported by detailed preclinical toxicology, by a clinical research unit that is prepared to handle unexpected contingencies, and by the oversight of a competent, multi-disciplinary review board. Patients should be in good physical health (excluding AD), and a comprehensive informed consent procedure must be instituted. Carefully planned and well run bridging studies represent a scientifically and ethically sound approach to drug development in the Alzheimer's population.