Targacept, Inc (NASDAQ: TRGT) today announced top-line results from a Phase 2 proof of concept trial of TC-5619 as a treatment for adults with attention deficit/hyperactivity disorder (ADHD). In the trial, conducted in non-smokers, TC-5619 did not meet the primary efficacy outcome measure, change from baseline on the Conners' Adult ADHD Rating Scale-Investigator Rated Total ADHD Symptoms score (CAARS-INV) after four, eight and 12 weeks of dosing.
Targacept announced positive top-line results from a separate Phase 2 trial of TC-5619 in cognitive dysfunction in schizophrenia (CDS) in January. TC-5619, a highly selective alpha7 neuronal nicotinic receptor modulator, is subject to license by Targacept's strategic collaborator AstraZeneca, with a decision expected in the second quarter of 2011.
The ADHD trial included a number of scales and assessments as secondary efficacy outcome measures. The results across all of these assessments indicate that TC-5619 had activity in this patient population, with TC-5619 outperforming placebo with statistical significance (as defined by the protocol, one-sided p-value < 0.10) approximately seven times more often than placebo outperformed TC-5619 by the same standard. TC-5619 performed best on the Conners' Adult ADHD Rating Scale-Subject Rated (CAARS-S), a patient self-rating scale, where the results favored TC-5619 with statistical significance (one-sided p-value < 0.10) on four of five subscales at 12 weeks.
TC-5619 was generally well tolerated in the trial, with no serious adverse events reported and no clinically significant difference between the TC-5619 dose group and the placebo dose group in discontinuations due to adverse events. Adverse events reported in at least five percent of patients in the TC-5619 dose group and at least twice as often as in the placebo dose group included headache (9%), rash (6%; resolved during treatment phase) and somnolence (6%).
"We continue to pursue a strategy of using initial Phase 2 development to gain clinical insights that help identify the indications for which our compounds will be best suited for later-stage development," said J. Donald deBethizy, Ph.D., Targacept's President and Chief Executive Officer. "While we did not see stimulant-like efficacy in this learning trial, the overall findings provide additional evidence that TC-5619 is active in a cognitively-impaired patient population, with the safety results adding to an impressive profile for a compound that has now been studied in more than 200 subjects. Coupled with positive outcomes from our prior Phase 2 study in patients with schizophrenia on measures of executive function, negative symptoms of schizophrenia and global change, we now have a foundation to guide future development of TC-5619."
Analyses of the full dataset from the ADHD trial are ongoing, and Targacept plans to present more detailed results at a future scientific meeting.
In addition to its completed Phase 2 trials in CDS and ADHD, Targacept is currently conducting clinical and non-clinical studies designed to support potential Phase 2 development of TC-5619 in a third indication with high unmet medical need, Alzheimer's disease.
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