OSI Pharmaceuticals, Inc. has announced the interim phase II study results showing that intravitreal injections of Macugen (pegaptanib sodium injection) resulted in better visual acuity outcomes in patients with macular edema due to central retinal vein occlusion (CRVO), compared with those receiving a sham injection. Over 90 per cent of patients maintained or improved vision (defined as a loss of less than 15 letters in visual acuity) at 30 weeks when treated with Macugen injections (0.3 mg or 1.0 mg) compared to approximately 69 per cent of those treated in the control arm. Patients treated with Macugen for 30 weeks had, on average, an improvement in visual acuity while the control group demonstrated a mean decrease in visual acuity from baseline to week 30 (7.5 letters improvement in the 0.3 mg group; 10.2 letters improvement in the 1 mg group; versus 1.9 letters loss in the sham group). Vision gain was seen with a single injection of Macugen within 6 weeks of treatment, versus a loss in the control group. The proportion of patients gaining 15 letters or more was 36 per cent in the 0.3 mg group and 39 percent in the 1.0 mg group, compared to 28 percent in sham controls. More complete trial results including a summary of safety and other secondary efficacy analyses from the trial will be presented at the 24th Annual Meeting of the American Society of Retina Specialists (ASRS), September 9-13, in Cannes, France.

"Retinal vein occlusion, or RVO, is a common cause of marked or total loss of vision in the middle-aged and elderly population. Despite the fact that more than 130,000 new cases of RVO are reported each year, there are currently no approved pharmacological treatments to treat the condition," said Anthony P. Adamis, M.D., Chief Scientific Officer, (OSI) Eyetech. "These data are important because they suggest that through selective VEGF inhibition, Macugen may be effective at targeting the underlying pathologies that play a significant role in promoting the vision loss associated with RVO."

This phase II randomized, dose-ranging, double-masked, multi-centre trial was conducted to determine the safety, efficacy and pharmacokinetics of Macugen in patients with recent vision loss due to macular edema associated with CRVO.

In the study, 98 patients were randomized to receive Macugen 1 mg or 0.3 mg or sham intravitreous injection, once every six weeks for 24 weeks. Endpoints included the difference in change from baseline mean visual acuity (ETDRS VA) between sham and 0.3 mg, and between sham and 1 mg, both at 30 weeks after five treatments. Other endpoints included optical coherence tomography (OCT), fluorescein angiography (FA) and photographic assessments, as well as population pharmacokinetics. Final assessments will be performed at week 52.

Macugen is the first selective VEGF inhibitor that has been approved in the US, Canada, the EU and several other countries for the treatment of all forms of neovascular (wet) age-related macular degeneration (neovascular AMD). It is administered in a 0.3 mg dose once every six weeks by intravitreal injection. Macugen is a pegylated anti-VEGF aptamer, which binds to vascular endothelial growth factor (VEGF). VEGF is a protein that plays a critical role in angiogenesis (the formation of new blood vessels) and increased permeability (leakage from blood vessels), two pathological processes that contribute to the vision loss associated with neovascular AMD.

Macugen is approved for neovascular AMD by regulatory authorities in the US, European Union, Canada, Brazil, Argentina, Peru, Pakistan, the Philippines and Switzerland, with filings submitted in 14 other countries. Macugen is now available in the US, Canada, UK, Germany, Sweden, Finland, Ireland, Austria, Turkey, Mexico, Philippines, Pakistan and Brazil.

OSI and Pfizer Inc. co-promote and co-develop Macugen in the US. OSI has granted Pfizer the exclusive rights to commercialize Macugen in countries outside the US pursuant to a royalty-bearing licensing agreement.

Macugen is contraindicated in patients with ocular or periocular infections or with known hypersensitivity to pegaptanib sodium or any other excipient of this product.