Pfizer and OSI Pharmaceuticals' Macugen (pegaptanib) significantly boosts visual acuity versus placebo, according to new Phase II data.

The study results showed that more than 90% of patients with a condition known as central retinal vein occlusion experienced visual improvement at 30 weeks, versus 69% in the control arm. Overall, the Macugen group saw a benefit to their visual acuity, with 7.5 letters improvement (on the vision chart) among low-dose 0.3mg receivers and 10.2 letters improvement in the higher dose 1mg cohort. This compared to a loss of 1.9 letters over 30 weeks amongst placebo receivers.

In addition, vision gain was seen with a single injection of Macugen within six weeks' treatment, compared to a loss in the control group, say Pfizer and OSI. Although more complete data will be presented at a medical meeting in September, the firms will be hoping these latest results help raise the profile of Macugen in a new use.

Retinal vein occlusion is a common cause of vision loss in older people, with more than 130,000 news cases reported every year in the USA alone. There are currently no pharmacological treatments to combat this condition, which is characterised by a blockage in the central retinal vein or one of its branches, leading to haemorrhages within the eye and vision loss.

Macugen is already approved in major markets, including the USA and Europe, for treating age-related macular degeneration. Most recently, it came under scrutiny in the UK - where it has just been launched - after Steve Winyard, head of public policy at the Royal National Institute for the Blind, said UK primary health care trusts (PCTs) are already blocking treatment with the drug on the grounds of cost ahead of a review by the country's cost-effectiveness body, the National Institute for Health and Clinical Excellence.