Merck's experimental eye drug matches standard of care in diabetic macular edema trial

Merck (MRK) said that its injectable treatment for diabetic macular edema, a serious eye disease affecting people with diabetes, was as effective as the current standard of care at improving visual sharpness in a late-stage clinical trial.

The 52-week study enrolled 984 patients. It found the experimental drug, remigromig, was non-inferior to Roche's (RHHBY) ranibizumab on mean change from baseline in best-corrected visual acuity, a test of vision while wearing proper corrective lenses.

Remigromig works by activating the Wnt pathway, a cell growth-regulating system, to help repair the retina's leaky blood-vessel barrier and reduce the swelling that blurs vision. "If approved, remigromig would be the first novel mechanism of action for retinal vascular diseases in more than two decades," said Louise Chen, an analyst at Scotiabank. Analysts said the results also strengthen Merck's ophthalmology pipeline, which could become an important therapeutic area for the group.

Investors responded favorably, with Merck's shares up 1.7 per cent in morning trading.

Safety is the main caveat. Merck said the drug was well tolerated but acknowledged that discontinuations due to certain retinal vascular complications were more frequent than with ranibizumab, and that it was analyzing the findings. Evan Seigerman, an analyst at BMO Capital Markets, said the full data were needed before the drug's commercial potential could be judged. "Safety remains a focus into the full data with more color needed on the imbalances noted in today's release," he said.

Diabetic macular edema occurs when damaged retinal blood vessels leak fluid into the macula, the part of the eye responsible for sharp, central vision. About 5.5 per cent of people with diabetes worldwide are affected, according to the US National Institutes of Health. Common treatments include anti-VEGF injections such as ranibizumab, which block or regulate the growth of blood vessels, as well as laser therapy and steroid injections or implants.

Merck will present the results at the American Academy of Ophthalmology's annual meeting next month.