Merck & Co. has poured out its Brunello data, revealing a mix of undifferentiated efficacy and concerning safety that led analysts to predict “limited competitive potential” in diabetic macular edema (DME).
The pharma paid $1.3 billion upfront in 2024 to buy the asset and the rest of Eyebiotech.
Merck shared topline results from the phase 2b/3 trial last month. At that time, Merck said its trispecific remigromig was noninferior to ranibizumab, the VEGF inhibitor that Roche’s Genentech sells as Lucentis in the U.S. However, the absence of numbers behind the primary endpoint hit, plus early details of an unfavorable adverse event (AE) profile, raised doubts about remigromig’s positioning in a competitive sector.
Those doubts intensified over the weekend, when Merck used the American Academy of Ophthalmology 2026 Annual Meeting to share full data from the trial.
The presentation included the numbers behind the AE findings that Merck touched on in its topline release. Proliferative diabetic retinopathy (PDR)—which is caused by abnormal new blood vessels on the surface of the retina—affected 6.7% and 6.1% of participants taking remigromig 0.5 mg and 0.8 mg, respectively, versus 0.9% for those on Lucentis. In the remigromig cohorts, 4.9% and 4.5% of people discontinued treatment due to AEs, versus 0.9% in the control arm.
Merck is performing additional analyses to further characterize the findings. The company hypothesized that “PDR rates may reflect natural disease progression in DME patients since remigromig focuses on repair and maintenance of the blood-retinal barrier rather than directly suppressing new vessel growth.” Merck pointed out that the PDR cases were “generally manageable,” but failed to reassure analysts.
“We see limited competitive potential for remigromig, but our broader Merck thesis remains intact,” BMO Capital Markets analysts said in a note to investors. “Based on the current profile, remigromig appears to offer weaker numerical efficacy, and a less favorable safety profile versus ranibizumab.”
“We believe the imbalances could limit physician enthusiasm, particularly given the availability of established anti-VEGF therapies with proven efficacy and safety profiles,” the analysts added.
The safety concerns were compounded by undifferentiated efficacy. Mean gains on the BCVA eye test after one year of treatment were 9.1 letters and 8.7 letters on the 0.5 mg and 0.8 mg remigromig doses, respectively, compared to 11.8 letters for the patients who received Lucentis. No secondary endpoints found remigromig superior to ranibizumab.
Another phase 2b/3 trial of remigromig in DME is ongoing. The trial, plus Year 2 personalized treatment intervals, could “provide additional context,” the analysts said. However, with Brunello leaving “a high bar for materially improving the asset’s positioning,” the analysts are already viewing the results as a reminder that not every deal will produce a commercially successful asset.
Merck provided a more upbeat assessment. Remigromig is the first new mechanism of action in more than 20 years to match anti-VEGF therapy in a pivotal DME study, Dean Li, M.D., Ph.D., the president of Merck Research Laboratories, said in a statement. Merck has consistently pointed to the 30% to 40% of DME patients failed by existing VEGF drugs to argue the need for a new mechanism in the indication.
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