Belite Bio is seeking US approval of its lead ophthalmology asset, tinlarebant, in Stargardt disease 1 (STGD1) following the positive results of a late-stage trial.
During the Phase III DRAGON study (NCT05244304), the oral small molecule offered a statistically significant 35.7% reduction in lesion growth rate compared with placebo, as measured by retinal imaging, achieving its primary endpoint.
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Post-hoc analysis, using an autoregressive covariance matrix under the mixed model for repeated measures (MMRM), saw a treatment effect size of 35.4% when accounting for the progressive nature of STGD1.
Tinlarebant also exhibited an impact on the fellow eye of patients, with 33.6% lesion growth reduction. In STGD1, the ‘fellow’ is the eye less impacted by lesional growth and degeneration, as Stargardt-associated retinal decline is often asymmetric between the eyes.
The drug also met a key secondary endpoint, slowing decreased autofluorescence (DAF) lesion growth in the study eye by 33.7% and the fellow eye by 32.7%.
Though a minimal change in visual acuity was observed after 24 months, Belite stated that this outcome was expected and consistent with natural history data.
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By GlobalDataDespite this, Quan Dong Nguyen, ophthalmology professor at the Byers Eye Institute at Stanford, noted that it was “only a matter of time” before the reduction in lesion growth triggered by tinlarebant could “translate into measurable benefits in visual function”.
The disease-modifying therapy (DMT) was also fairly well tolerated among the enrolled paediatric patient population, with four out of the 104 enrolled patients discontinuing treatment. These discontinuations were not related to non-ocular adverse events (AEs).
Tinlarebant acts by reducing the accumulation of vitamin A-based toxic byproducts in the retina – a method that has now been shown to hinder lesional growth and slow disease progression.
Tinlarebant’s potential as first STGD1 treatment
Following the positive results of the DRAGON study, Belite is seeking tinlarebant’s approval in STGD1, which will see the company submit a New Drug Application (NDA) to the US Food and Drug Administration (FDA) during the first half of 2026.
According to Belite’s chair and CEO Dr Tom Lin, the biotech will also engage with other regulatory agencies to make tinlarebant accessible in other markets. Agencies in China and the UK have accepted both new drug and conditional marketing applications for tinlarebant based on interim analysis results.
If the drug were to secure FDA approval, it would become the first approved therapy available to US patients with STGD1, which is the most common reason for juvenile macular dystrophy.
Investors appear to be excited about tinlarebant’s prospects, as Belite’s stock value rose 12% on the announcement, from $137.44 at market close on 28 November to $154.02 at market close on 1 December. The US-based biotech’s market cap currently stands at $5.37bn.
Tinlarebant’s potential drawbacks
While Sara Reci, managing analyst at GlobalData, touted the Phase III DRAGON results as a “genuine breakthrough for STGD1”, she noted that the drug’s functional benefit on visual acuity could throw a spanner in the works.
She stated: “This creates the same regulatory challenge that plagued geographic atrophy (GA) therapies Izervay (avacincaptad pegol) and Syfovre (pegcetacoplan) in Europe.
“It will also complicate patient counselling, as they must accept continued visual decline, despite treatment.”
While Reci believes that the FDA will likely accept anatomic endpoints given tinlarebant’s gained both breakthrough and orphan disease designations, the lack of functional benefit observed in the DRAGON trial poses a “significant real-world adherence risk that could undermine the therapy’s effectiveness outside of controlled trials”.
However, she observed that the positive outcomes of the DRAGON trial could bode well for tinlarebant’s potential in GA, as well as potentially accelerating its development in the indication.
Reci concluded: “For ophthalmology more broadly, DRAGON validates RBP4 inhibition and structural imaging endpoints as a feasible regulatory path in inherited retinal disease, which could derisk programmes in GA and related indications where tinlarebant is already in Phase III.”
