Key Development
Merck’s remigromig has met the primary endpoint in the pivotal Phase 2b/3 BRUNELLO trial, validating Wnt-pathway activation as a clinically active approach in diabetic macular edema. Yet the full AAO 2026 dataset turns the story from a straightforward clinical win into a commercial differentiation problem.
Among 984 participants, monthly remigromig 0.5 mg and 0.8 mg produced mean one-year BCVA gains of 9.1 and 8.7 ETDRS letters, respectively, versus 11.8 letters with monthly ranibizumab. Both doses met the prespecified noninferiority threshold, but no secondary endpoint demonstrated superiority.
The more challenging signal came from safety. Adverse events associated with proliferative diabetic retinopathy occurred in 6.7% and 6.1% of remigromig-treated patients, compared with 0.9% on ranibizumab. Treatment discontinuations due to adverse events were also higher at 4.9% and 4.5%, versus 0.9%. Merck is conducting additional analyses to understand the imbalance.
Why It Matters
- BRUNELLO validates an ophthalmic mechanism outside VEGF. Remigromig is the first pivotal biologic targeting Wnt signaling to demonstrate noninferior visual acuity versus established anti-VEGF therapy.
- Noninferiority is not differentiation. Numerical vision gains were lower than ranibizumab, although within the trial’s statistical margin.
- The safety imbalance could constrain adoption, particularly because proliferative retinopathy is already a clinically serious complication of diabetic retinal disease.
- Treatment burden is becoming a competitive benchmark. Eylea HD can now be dosed as infrequently as every 20 weeks in appropriate DME patients, while Vabysmo supports regimens extending to 16 weeks.
Healthcare Insight Analysis
Healthcare Insight believes BRUNELLO illustrates an increasingly important rule in mature specialty markets:
mechanistic novelty only creates commercial value when it solves a clinically meaningful problem better than existing therapy.
Merck acquired EyeBio in 2024 for $1.3 billion upfront plus as much as $1.7 billion in potential milestones, with remigromig serving as the centerpiece of an effort to build a differentiated ophthalmology pipeline.
The scientific thesis remains compelling.
Anti-VEGF therapy suppresses vascular signaling responsible for leakage and neovascularization. Remigromig instead activates the Wnt pathway to promote repair and maintenance of the blood-retinal barrier.
That makes the asset genuinely mechanistically differentiated.
But the commercial benchmark has moved.
Monthly ranibizumab is a useful control for demonstrating biological activity. It is less useful as the sole benchmark for what physicians can offer patients today.
Vabysmo has pushed DME treatment toward intervals of up to 16 weeks. Eylea HD’s U.S. label now allows some responsive patients to extend dosing to every 20 weeks after the first year.
Against that landscape, a new monthly intravitreal therapy needs to compensate with something substantial:
better efficacy, better safety, superior activity in inadequate responders, or materially greater durability.
BRUNELLO has not yet demonstrated those advantages.
That does not make remigromig clinically irrelevant.
Merck notes that as many as 40% of patients have persistent DME activity after six months of current treatment, creating a meaningful population for alternative biology.
The more attractive development thesis may therefore shift from replacing anti-VEGF broadly to identifying patients for whom anti-VEGF biology is insufficient.
The strategic question becomes:
Can Wnt activation rescue or meaningfully improve outcomes in patients who remain inadequately controlled despite VEGF suppression?
If the answer is yes, remigromig may still have a strong role even without outperforming anti-VEGF therapy in an all-comer trial.
The next datasets matter disproportionately.
BAROLO, the second pivotal DME study, can test reproducibility. Meanwhile, BRUNELLO’s second year uses personalized treatment intervals, offering a chance to determine whether Wnt biology ultimately provides a durability advantage not visible during fixed monthly dosing.
The EyeBio transaction should also be viewed as a portfolio acquisition rather than a single-asset wager.
Merck is advancing MK-8748, a bispecific candidate combining Tie2 activation with VEGF inhibition, across multiple pivotal DME and wet-AMD studies. That suggests the company is building a broader retinal vascular disease platform around barrier restoration and vessel stabilization rather than relying exclusively on remigromig.
Market Implications
Merck: BRUNELLO validates Wnt biology but has not yet validated a strong commercial product profile.
Roche and Regeneron: increasingly durable anti-VEGF regimens raise the entry bar for every new retinal therapy.
Ophthalmology biotech: novel biology must translate into better efficacy, safety, durability or responder segmentation.
Investors: BAROLO, year-two dosing data and the PDR analysis matter more than the headline primary-endpoint success.
ANALYTICAL MATRIX
| Dimension | BRUNELLO Signal | Strategic Value | Remaining Risk |
| Efficacy | BCVA noninferiority | Validates Wnt biology | No superiority |
| Safety | Higher PDR imbalance | Needs characterization | Adoption risk |
| Dosing | Monthly in Year 1 | Clear exposure | No burden advantage |
| Mechanism | Wnt agonism | New retinal pathway | Unclear commercial edge |
| Portfolio | Remigromig + MK-8748 | Broader ophthalmology platform | EyeBio return uncertain |
BRUNELLO is therefore not a scientific failure.
It is evidence that in a therapeutic category with highly effective incumbents, proving that a drug works is only the first hurdle. The harder commercial question is proving why physicians should change what already works.