Merck's eye drug remigromig matches ranibizumab in a pivotal trial, with more eye bleeding and dropouts

Merck said on Thursday that its experimental eye drug remigromig met the main goal of BRUNELLO, the first of two pivotal trials in diabetic macular edema, a leading cause of vision loss in people with diabetes. At 52 weeks, both doses tested were non-inferior to ranibizumab, an established treatment, on improvement in visual acuity, according to the company's release.

Merck shares were at $148.25 in early afternoon, up 0.11%, according to Nasdaq data.

What "met the goal" means here

"Meets trial goal" reads like a clear win. The actual result is narrower. Non-inferiority means remigromig was shown to be not meaningfully worse than ranibizumab. It was not shown to be better. Ranibizumab has been on the market for years. David Guyer, chief executive of Merck's EyeBio unit, called it the first new mechanism of action in 20 years to reach non-inferiority with anti-VEGF therapy in a Phase 3 trial. That is a scientific milestone. It is not yet a commercial argument, because doctors need a reason to switch.

Three details from the release matter for how the market reads this:

• Side effects ran higher. Merck said patients on remigromig had higher rates of proliferative diabetic retinopathy (a more advanced stage of the disease), vitreous hemorrhage (bleeding into the gel of the eye) and discontinuations because of adverse events than patients on ranibizumab. It said further analyses are under way. It also called both doses "generally well tolerated."
• No numbers yet. The release gives no letter-score gains, no confidence intervals and no side-effect rates. Those come at the American Academy of Ophthalmology meeting in New Orleans on Oct. 10.
• Same dosing schedule. All 984 patients, split evenly across two remigromig doses and ranibizumab, were dosed every four weeks in year one. The trial therefore cannot yet show a less frequent injection schedule, which is often how newer eye drugs win market share. In year two, dosing moves to a personalized interval, and those results will matter more.

The price of the bet

Remigromig came to Merck with its 2024 purchase of EyeBio, which cost $1.3 billion in cash upfront plus up to $1.7 billion in milestone payments, BioPharma Dive reported at the time. Merck puts the U.S. patient pool at an estimated 1.6 million people with diabetic macular edema. It says up to 40% of them do not respond, or respond only partly, to current treatments. That group is where a drug with a different mechanism would have to prove itself.

A second pivotal trial, BAROLO, is still running in the same disease. Merck is also testing a second EyeBio drug, MK-8748, in four pivotal trials across wet age-related macular degeneration and diabetic macular edema. The company said it will discuss the BRUNELLO results with regulators.

What traders are watching

• The side-effect rates at AAO on Oct. 10, and whether the imbalance in eye bleeding is large enough to limit use.
• Whether BAROLO confirms the result, since regulators often look for two supportive trials.
• Year-two BRUNELLO data on how long patients can go between injections.

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Sources: Merck press release, Sept. 24, 2026; BioPharma Dive; Nasdaq. This is market information, not investment advice.