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Pegaptanib Shows Positive Visual, Anatomical Outcomes in Phase 2 Trial for Diabetic Macular Edema
NEW YORK, May 3 /PRNewswire-FirstCall/ -- Eyetech Pharmaceuticals, Inc. a biopharmaceutical company that specializes in the development and commercialization of novel therapeutics to treat diseases of the eye, and Pfizer Inc, today announced that a phase 2 study of Macugen, an investigational drug, showed positive visual and anatomical outcomes for diabetic macular edema (DME). Diabetic retinopathy is the leading cause of blindness in people less than 50 years of age in developed countries. DME is the leading cause of vision loss in diabetic retinopathy.
The preliminary data were statistically significant for Macugen (0.3 mg) vs sham injection with respect to zero (0) or greater, 1 or greater and 2 or greater line gainers at 36 weeks. The lowest efficacious dose for this trial (0.3 mg) was the same as that for Macugen in age-related macular degeneration (AMD).
* In the Macugen (0.3 mg) group, 73% of patients gained 0 or more lines compared to 51% in the sham injected group, a 43% relative treatment effect (p=0.02). * In the Macugen (0.3 mg) group, 59% of patients gained 1 or more lines compared to 34% in the sham injected group, a 73% relative treatment effect (p=0.01). * In the Macugen (0.3 mg) group, 34% of patients gained 2 or more lines compared to 10% in the sham injected group, a 240% relative treatment effect (p=0.003). * In the Macugen (0.3 mg) group, 18% of patients gained 3 or more lines compared to 7% in the sham injected group, a 157% relative treatment trend.
Optical coherence tomography (OCT), an imaging technique, which may anatomically quantify retinal thickness or edema, showed a 300% relative reduction trend in retinal thickness for Macugen (0.3 mg) compared to controls (50.79 micrometers vs. 12.68 micrometers). In the geometric center of the macula, that region directly responsible for high acuity vision, the odds of a decrease in retinal thickness of 75 micrometers or more is 4 times larger for the Macugen (0.3 mg) group vs. controls (p=0.0078).
A preliminary look at the draft safety data suggests that the safety profile of Macugen in patients with DME appears to be well-tolerated. Further detailed analysis of the safety data is ongoing. In approximately 1200 patients with age-related macular degeneration (a non-diabetic condition in older patients) Macugen seems to be well-tolerated systemically at all three doses. Most of the adverse events appear mild, transient, and attributed by investigators to the injection procedure rather than the study drug.
The preliminary data from this phase 2 study, combined with results from likely future studies, may ultimately allow Eyetech and Pfizer to expand the use of Macugen into a second large market such as diabetic retinopathy.
"The preliminary data from this proof of principle phase 2 clinical trial highlight a new way to potentially treat patients with diabetic retinopathy. We are encouraged that the use of Macugen may be able to be expanded into a second large area of unmet medical need in addition to wet AMD, assuming future confirmatory trials," said David Guyer, M.D., Chief Executive Officer and Co-founder of Eyetech Pharmaceuticals. "These preliminary data suggest that inhibiting the pathological isoform VEGF165 may be beneficial for patients with diabetic macular edema, the leading cause of vision loss in patients with diabetes."
"We are encouraged by the findings of this study and the impact Macugen could potentially have on diabetic retinopathy," said Michael Widlitz, M.D., Vice President, Pfizer Inc. "There is a tremendous unmet medical need for innovative treatments to help patients suffering from this debilitating disease. Pfizer is committed to promote healthy aging, and one of our areas of focus is ophthalmology. Macugen is the first drug targeting the underlying mechanism for the most common causes of severe vision loss in the western world, AMD and diabetic retinopathy. These new data may potentially add another large disease area that may benefit from treatment with Macugen," said Widlitz.
About the DME Study
This multi-center phase 2 study enrolled 169 patients in a randomized, double-masked placebo controlled protocol. Patients received varying doses (0.3 mg, 1 mg, 3 mg) of Macugen via intravitreous injections or sham every six weeks for at least 12 weeks and then at the discretion of the investigators. The patients enrolled in this study were required to have been eligible for thermal laser therapy for DME.
About Diabetic Retinopathy
DME is a common complication of diabetic retinopathy, a disease affecting the blood vessels of the retina. Diabetic retinopathy results in multiple abnormalities in the retina, including retinal thickening or edema, hemorrhages, impeded blood flow, excessive leakage of fluid from blood vessels and, in the final stages, abnormal blood vessel growth. This blood vessel growth can lead to hemorrhages and severe retinal damage. When the blood vessel leakage of diabetic retinopathy causes swelling in the macula, it is referred to as DME.
According to the American Diabetes Association (ADA) there are at least 18 million people diagnosed with diabetes in the United States. After 10 years of disease duration, 75% of diabetics have developed some form of diabetic retinopathy. DME is the leading cause of vision loss for patients with diabetes, and according to the ADA, in the US there are approximately 500,000 people suffering from DME, with approximately 75,000 new cases each year. There is a significant unmet medical need for a new therapy for this disease.
Macugen is a pegylated anti-VEGF aptamer, which binds to and thus inhibits the activity of vascular endothelial growth factor (VEGF) that has also met its pivotal phase 2/3 primary efficacy endpoint for the treatment of wet AMD. Eyetech and Pfizer are jointly planning to file in the third quarter of 2004 a new drug application (NDA) with the FDA seeking approval for Macugen in wet AMD. The FDA has given "fast track" designation to Macugen for the treatment of both wet AMD and DME.
VEGF is a protein that plays a critical role in angiogenesis (the formation of new blood vessels) and permeability (leakage from blood vessels) of vessels. VEGF is the most potent permeability factor currently characterized. DME is characterized by enhanced vascular permeability. It is believed that by specifically blocking the pathological isoform VEGF165, Macugen may inhibit the permeability effects characteristic of diabetic macular edema.
Eyetech scientists and other independent laboratories have shown in preclinical studies that administration of VEGF165 creates a condition virtually indistinguishable from human diabetic retinopathy. In addition, in separate preclinical studies, Macugen injections significantly improved the signs of diabetic retinopathy.
Source: Eyetech Pharmaceuticals, Inc.