Wet age-related macular degeneration (AMD) affects approximately five million patients worldwide, and this patient population is continuing to grow. Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula, the central area of the retina responsible for detailed vision. These blood vessels are often fragile and can leak blood and fluid below the macula, causing damage to the photoreceptors and vision loss. AMD, a disease associated with aging, gradually destroys a patient’s vision. It is the most common cause of vision loss in patients aged 50 or older and represents a market of more than $1 billion annually.
Abnormalities in the vitreomacular interface (the interface of the vitreous and macula) have been implicated in wet AMD, and recent publications have demonstrated that approximately one-third of AMD patients have focal vitreomacular adhesion (VMA). VMA is a condition in which the vitreous gel, in the centre of the eye, has an abnormally strong adhesion to the retina at the back of the eye, and research has found that this adhesion occurs in the same location as the wet AMD pathology (Robison, C.D. et al, 2009; Mojana, J. et al, 2008; Krebs, I. et al, 2007).
ThromboGenics is developing microplasmin as a non-surgical treatment for vitreomacular adhesion. Microplasmin has the potential to separate the vitreous from the retina and – because wet AMD is thought to result from the abnormal connection of the vitreous to the retina – it is, therefore, anticipated that microplasmin could potentially prevent the progression of this highly prevalent disease.
The MIVI (Microplasmin for IntraVitreous Injection) 5 trial is a Phase II, randomized, double-blind, sham-controlled trial of microplasmin intravitreal injection (125 μg) for the treatment of focal vitreomacular adhesion (separation of the vitreous from the retina) in patients with wet AMD. The trial will enroll approximately 100 patients at up to 20 centers across five European countries. The primary endpoint of the trial is non-surgical resolution of vitreomacular adhesion, defined as the separation of the vitreous from the retina, by 28 days. This will be assessed by the Central Reading Center based on optical coherence tomography (OCT) images. Additional measures of efficacy and safety will also be assessed over a one year follow-up period.
Microplasmin has the potential to transform the treatment of several other important back-of-the-eye diseases, as well as AMD. Microplasmin is currently being evaluated in a Phase III programme of approximately 640 patients for the non-surgical treatment of focal vitreomacular adhesion.
Dr Patrik De Haes, CEO of ThromboGenics, commented, ‘We are very pleased to announce the start of a Phase II trial of microplasmin in such a significant condition as AMD. It is increasingly clear that vitreomacular adhesion plays a key role in AMD sufferers with a poorer prognosis. Microplasmin’s potential to cleave the vitreous from the retina could therefore represent an important advance in the treatment of this patient group.’