Targacept to advance drug into clinicals

Targacept, a US clinical-stage biopharmaceutical company developing a new class of drugs known as NNR Therapeutics, says it plans to advance TC-5214, one of two enantiomers of mecamylamine HCl, into clinical development as an augmentation therapy for patients who are inadequate responders to first-line antidepressant treatments. Targacept expects to initiate a Phase I trial of TC-5214 in the first quarter of 2008 and to begin Phase II development soon thereafter.

The company has no current plans to conduct further clinical development of mecamylamine, which is a racemic compound comprised of two mirror image halves known as the S+ and R- enantiomers. TC-5214 is the S+ enantiomer of mecamylamine. In a Phase II trial in patients who did not respond adequately to first-line treatment with citalopram hydrobromide that Targacept completed in 2006, whose citalopram regimen was augmented with mecamylamine showed greater improvement on symptoms of depression and irritability than patients who received citalopram and a placebo. Citalopram hydrobromide is a commonly-prescribed treatment for depression from the drug class selective serotonin reuptake inhibitors that is marketed as Celexa in the USA.

Targacept recently presented research findings comparing the activity of TC-5214, mecamylamine and the R-enantiomer of mecamylamine at the 20th European College of Neuropsychopharmacology held in Vienna, Austria (see also Marketletter October 22). Those results illustrated the superior potency of TC-5214 relative to mecamylamine at specific NNR subtypes believed to have therapeutic application for depression, as well as a favorable preclinical efficacy profile, the firm said. In light of the Phase II results with mecamylamine described above, these findings suggest the compelling potential of TC-5214 as an augmentation treatment for major depression.