The DIRECT, the first Programme launched on November 1, 2000 designed to establish whether treatment with an angiotensin II type 1 (AT1) receptor blocker, candesartan cilexetil, targeting the renin angiotensin system (RAS), can provide effective treatment against the onset and progression of diabetic retinopathy has been completed. In this double-blind programme, patients are assigned to receive 32 mg of candesartan cilexetil or placebo.
The DIRECT is being coordinated through EURODIAB, a European diabetes research network, based at University College, London, and Imperial College, London, and overseen by an independent Steering Committee, chaired by Professor Anne-Katrin Sjolie, University of Southern Denmark, Odense. The Steering Committee consists of leading ophthalmologists, diabetologists and epidemiologists, and has scientific responsibility for the DIRECT programme.
"We are very pleased to have completed this initial phase of the DIRECT Programme, with more patients than originally planned. DIRECT represents an important step forward in the fight against visual loss caused by diabetic retinopathy", said Professor Sjolie. "This important Programme will tell us more about the potential for using a drug such as candesartan to halt progression of, and possibly prevent, diabetic retinopathy, a common and frightening condition among people with diabetes. We look forward to the results from the DIRECT Programme, which will hopefully identify candesartan as a new addition to current treatment and help to limit retinal damage and, in some patients, preserve vision."
Retinopathy can ultimately lead to blindness in both type 1 and type 2 diabetic patients. In the developed world, diabetic retinopathy is a leading cause of blindness in the working population and the most commonly feared complication of diabetes. In patients with a 20 year history of diabetes, nearly all type 1 patients, and over 60 per cent of type 2 patients, will have developed some degree of diabetic retinopathy.
DIRECT are three separate clinical studies within one programme. Each study of the programme will investigate the effect of candesartan cilexetil in diabetic, normotensive (the type 2 patients can be either normotensive or treated hypertensive), normoalbuminuric (normal renal function) patients.
The three studies will investigate the effects of candesartan cilexetil in:
1. Type 1 diabetic patients without retinopathy for primary prevention.
2. Type 1 diabetic patients with retinopathy for secondary prevention.
3. Type 2 diabetic patients with retinopathy for secondary prevention.
The rationale for DIRECT arose from the promising results of the EURODIAB Controlled Trial of Lisinopril in Insulin dependent Diabetes (EUCLID). Analysis of the data indicated that the ACE-inhibitor lisinopril could have a positive effect in preventing and reducing the severity of diabetic retinopathy. However, a properly designed trial of sufficient size is needed to evaluate the role of RAS modulation in the treatment of this condition.
Candesartan cilexetil was chosen for DIRECT because it may offer a more complete blockade of the RAS with improved tolerability.
Dr Michael George, Deputy Managing Director, European Development, Takeda Europe R&D Centre, commented, "The DIRECT Programme is the largest undertaking of its kind to expand our knowledge about the benefits of RAS blockade in diabetic retinopathy. Takeda and AstraZeneca are committed to supporting the DIRECT Programme, and are hopeful that the results will lead to a significant improvement in the treatment of people with diabetes."
The DIRECT Programme is being conducted and jointly sponsored by Takeda Chemical Industries Ltd. and AstraZeneca.
Candesartan cilexetil is marketed worldwide under the brand name of Blopress by Takeda and Atacand by AstraZeneca in around 70 countries.