AstraZeneca has posted data on the extended release version of its blockbuster Seroquel which suggests that the schizophrenia drug could prove to be effective as a treatment for depression.

The company presented data at the 7th International Forum on Mood and Anxiety Disorders in Budapest, Hungary, which showed that patients who received Seroquel XR (quetiapine fumarate) extended-release tablets, once-daily experienced significant reductions in symptom severity compared to those on placebo in each of three trials, which investigated the drug as monotherapy in major depressive disorder, adjunctive treatment in patients with MDD with inadequate response to existing antidepressants and as a monotherapy in generalised anxiety disorder.

These studies are part of a clinical development programme that involved over 7,000 patients and the results were described by Stuart Montgomery of Imperial College in London and author of the MDD monotherapy study, as “remarkable”. He added that all of the doses of the drug examined provided improvements in MDD and GAD symptoms and “results from further studies that are still ongoing will add to our understanding of Seroquel XR in these conditions”.

Martin Brecher, executive director of medical science at AstraZeneca, said the data are very encouraging and suggest Seroquel XR “has the potential to provide a new treatment choice in this area particularly among patients who fail antidepressant therapy with existing treatment”. Noting that new therapy options are needed for treating MDD and GAD because currently available antidepressants do not achieve symptom remission in a substantial proportion of patients, he added that AstraZeneca plans regulatory submissions in 2008.

The news pushed AstraZeneca shares as investors look at a possible fresh income from a successful drug. Sales of the original version of Seroquel for schizophrenia and bipolar disorder for the first nine months of the year hit $2.94 billion but its patents are being challenged.

Seroquel XR was launched in the USA in May and received approval in The Netherlands at the end of August.