Bayer's Eylea (VEGF Trap-Eye) is not more effective than its competitor Lucentis to treat patients with diabetic macular edema, the German Institute for Quality and Efficiency in Health Care (IQWiG) has found.

The opinion could deal a major blow to Bayer's hopes of having the drug reimbursed by the German public health insurance system - the country's cost-benefit agency G-BA is due to publish an assessment of Eylea in March 2015.

IQWiG compared trial data on Eyelea, developed by Bayer in cooperation with Regeneron, and Novartis's Lucentis for treatment for the diabetic eye condition and found there was no relevant difference between the two, either in terms of how well patients could see or in terms of side effects.

The German institute in the past has come to similar conclusions on Eylea's effectiveness to treat other eye conditions. Last year, for example, it said it could not assess its possible advantages in treating wet age-related macular degeneration, a leading cause of blindness in the elderly, because Bayer had not provided relevant data.

Bayer has said it will respond to IQWiG's assessment, adding it was convinced of Eylea's benefit to patients. The German group's HealthCare arm expects the drug to generate more than €1.5 billion in peak annual sales.