Targacept, Inc. (NASDAQ: TRGT) today announced top-line results from a Phase 2 clinical trial of AZD1446 conducted by AstraZeneca in adults with attention deficit/hyperactivity disorder (ADHD). The study was one of several early clinical studies designed by AstraZeneca to obtain, in addition to safety and tolerability information, a signal of efficacy to guide dosing in potential later-stage development of AZD1446 in either or both of Alzheimer's disease and ADHD. AZD1446 is a selective modulator of the alpha4beta2 neuronal nicotinic receptor and was licensed by Targacept to AstraZeneca pursuant to a 2005 collaboration agreement.
“While we are disappointed in the results on the primary outcome measure in this ADHD trial, we are encouraged by the memory and learning findings from the CogState test battery and believe they support further study of AZD1446 as a treatment for Alzheimer's disease”
The study was a multi-center, randomized, double-blind, placebo-controlled, cross-over trial that assessed the efficacy, safety and pharmacokinetics of two weeks of treatment with AZD1446 as compared to placebo. Each subject was classified as a user of nicotine products or a non-user of nicotine products. Non-nicotine users received placebo and two out of three oral AZD1446 dose regimens, and nicotine users received placebo and two oral AZD1446 dose regimens.
In the trial, AZD1446 did not improve core symptoms of ADHD, as compared to placebo, as measured by the primary outcome measure, the Conners' Adult ADHD Rating Scale-Investigator Rated Total ADHD Symptoms score (CAARS-INV). Based on this finding, Targacept does not expect AstraZeneca to progress AZD1446 as a treatment for ADHD. A decision by AstraZeneca as to potential future development of AZD1446 in Alzheimer's disease is expected in the coming months.
Positive results were obtained in the study on three of five tasks of the CogState computerized test battery, secondary outcome measures designed to assess important cognitive functions such as learning and memory. Non-nicotine using subjects who received 80mg of AZD1446 once daily showed an improvement on the Groton Maze Learning Task>
AZD1446 was generally well tolerated in the study, and no serious adverse events were reported. Further analyses of the full dataset from the trial are ongoing.
"While we are disappointed in the results on the primary outcome measure in this ADHD trial, we are encouraged by the memory and learning findings from the CogState test battery and believe they support further study of AZD1446 as a treatment for Alzheimer's disease," said J. Donald deBethizy, Ph.D., Targacept's President and Chief Executive Officer.
In addition to the trial in adults with ADHD, the AZD1446 program includes three other early clinical studies intended to inform a decision by AstraZeneca as to potential future development in Alzheimer's disease. Two of these studies have completed. In a four-week trial designed primarily to evaluate the safety and tolerability of AZD1446 when administered with donepezil, the most commonly prescribed Alzheimer's disease treatment, to Alzheimer's disease patients, AZD1446 exhibited a safety and tolerability profile acceptable for further development. As expected with a short dosing period and small number of subjects, AZD1446 did not show an effect on surrogate measures of cognition and global function in the study. In a separate trial designed to explore the effects of a single dose of AZD1446 in healthy volunteers with drug-induced cognitive impairment, pro-cognitive signals were observed on various secondary outcome measures, but neither AZD1446 nor the positive comparator donepezil demonstrated a statistically significant effect on the study's primary outcome measure. Results from a fourth trial, designed to evaluate the pharmacodynamic effect of AZD1446 and donepezil on brain response in Alzheimer's disease patients as assessed by electroencephalography (EEG), are expected early next year.
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