AstraZeneca has submitted a supplemental New Drug Application (sNDA) to the US Food and Drug Administration (FDA) for once-daily Seroquel XR (quetiapine fumarate) Extended-Release Tablets to seek approval for the treatment of major depressive disorder (MDD) as monotherapy, adjunct therapy, and maintenance therapy in adult patients.

MDD affects 15 million American adults - between 5 and 8 percent of the population each year - and today it is often treated with generic or branded antidepressants. Studies have shown that at least one-third of patients with MDD treated with antidepressants fail to achieve a satisfactory response. The American Psychiatric Association Practice Guidelines recommend switching to a medication in another class when two medications from the same class have proven ineffective. AstraZeneca has investigated the use of Seroquel XR, an atypical antipsychotic, in the treatment of MDD, aiming to develop another potential treatment option, including treatment for patients who have failed or had an inadequate response to another antidepressant therapy.

The MDD submission is based on seven phase III, placebo-controlled studies that assessed the efficacy and safety of once-daily treatment with Seroquel XR in patients diagnosed with MDD. Studies 1, 2, 3, and 4 were acute monotherapy studies involving 2,116 patients; Studies 6 and 7 were acute adjunct therapy studies (with ongoing antidepressant therapy) involving 939 patients who had an inadequate response to an antidepressant therapy; and Study 5 was a longer-term (up to 78 weeks) monotherapy maintenance study involving 1,854 patients. The acute studies included in this submission used the Montgomery-Åsberg Depression Rating Scale (MADRS) as the primary assessment of depression symptoms. In the longer term study (Study 5), the primary assessment was time to a depressed event using criteria including MADRS. Doses of 50 mg, 150 mg and 300 mg of Seroquel XR were studied in the MDD programme. Across the whole programme, patients entering treatment in these seven clinical studies were drawn from 27 countries - three-quarters of the patients were in North America - a further 10 per cent were in Western Europe, 6 per cent in Eastern Europe and the remainder were in Asia, South America, South Africa and Australia.

Seroquel XR is approved in the US and 18 further countries for the treatment of schizophrenia in adult patients and for maintenance treatment of schizophrenia in adult patients. It was launched in the US in 2007 and last month AstraZeneca announced the submission of two separate sNDAs to the FDA for Seroquel XR seeking approval for the treatment of manic episodes associated with bipolar disorder and the treatment of depressive episodes associated with bipolar disorder - these remain under review by the FDA. In addition to the submission for MDD, the clinical development programme and planned regulatory filings for Seroquel XR extend to generalised anxiety disorder (GAD).

Launched in 1997, Seroquel (quetiapine fumarate) is approved in 88 countries for the treatment of schizophrenia, in 79 countries for the treatment of bipolar mania, and in 11 countries including the USA for the treatment of bipolar depression. Global sales of Seroquel for 2007 passed the $4 billion mark for the first time, up 15 per cent on the previous year.

ic pain. Symptomatically, a major depressive episode in MDD is similar to a depressive episode of bipolar disorder with the major distinguishing feature between the disorders being the absence of manic or hypomanic symptoms in MDD. It has been reported that 69 per cent of patients with bipolar disorder were misdiagnosed, with the most frequent misdiagnosis being MDD.