Ophthalmology · Clinical trials
Diabetic Retinopathy Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About diabetic retinopathy — and why its trials are hard
Diabetic retinopathy (DR) is a progressive microvascular complication of diabetes and a leading cause of vision loss in working-age adults. It ranges from non-proliferative disease (microaneurysms, haemorrhages, capillary non-perfusion) to sight-threatening proliferative DR (PDR) with neovascularisation, vitreous haemorrhage and tractional detachment. For decades panretinal photocoagulation (PRP) was the standard for PDR, ablating ischaemic retina to regress neovascularisation. The landmark DRCR.net Protocol S showed intravitreal ranibizumab was non-inferior to PRP for visual acuity at two years while better preserving peripheral field and reducing vitrectomy. Anti-VEGF agents (aflibercept, ranibizumab) are now approved to improve DR severity, measured on the Diabetic Retinopathy Severity Scale (DRSS). PANORAMA and Protocol W tested proactive aflibercept in non-proliferative disease, showing robust DRSS improvement and fewer vision-threatening complications, though Protocol W found no visual-acuity benefit from prophylaxis. Regular screening, glycaemic and blood-pressure control remain foundational, with pharmacotherapy reserved for advanced or high-risk eyes.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| aflibercept (Eylea) | 2019 | Diabetic retinopathy (with or without DME) | PANORAMA / DRCR.net Protocol S | ≥2-step improvement in DRSS score | PANORAMA: ~65% of aflibercept eyes achieved ≥2-step DRSS improvement at week 52 vs ~15% sham |
| ranibizumab (Lucentis) | 2017 | Diabetic retinopathy | DRCR.net Protocol S / RISE and RIDE | Visual acuity and DRSS; non-inferiority vs panretinal photocoagulation | Protocol S: ranibizumab non-inferior to PRP for BCVA at 2 years (~+2.8 letters), with less peripheral field loss and fewer vitrectomies |
| aflibercept 8 mg (Eylea HD) | 2023 | Diabetic retinopathy (extended dosing) | PHOTON (label extension) | DRSS improvement / maintained control at extended intervals | High-dose aflibercept maintained retinopathy control at dosing intervals up to every 12–16 weeks |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in diabetic retinopathy development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| ruboxistaurin (PKC-beta inhibitor) — PKC-DRS2 | Reduced sustained moderate visual loss vs placebo, but FDA issued a non-approvable/approvable letter requiring an additional confirmatory trial; never approved for DR | Single pivotal trial insufficient; modest effect on a secondary-type visual endpoint rather than DR progression; program ultimately discontinued |
| aflibercept (prophylactic, non-proliferative DR) — DRCR.net Protocol W | Reduced progression to PDR and centre-involved DME but showed no visual-acuity benefit vs sham at 4 years | Untreated eyes that developed complications were rescued and caught up in vision, undermining the rationale for proactive anti-VEGF in eyes with good baseline acuity |
Choosing the right endpoint
Primary endpoints that matter in diabetic retinopathy trials
- DRSS ≥2-step improvement — Regulatory endpoint for DR severity; two or more steps on the ETDRS Diabetic Retinopathy Severity Scale reflects meaningful anatomical regression
- BCVA (ETDRS letters) — Best-corrected visual acuity change; core functional outcome, though many NPDR eyes start with good vision limiting measurable gains
- Progression to PDR / vision-threatening complications — Rate of developing proliferative disease, vitreous haemorrhage or centre-involved DME; used in PANORAMA and Protocol W
- Peripheral visual field / vitrectomy rate — Safety and quality-of-life measures distinguishing anti-VEGF from panretinal photocoagulation
How iNGENū runs diabetic retinopathy trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Diabetic Retinopathy clinical trials — FAQs
Can anti-VEGF injections replace laser for proliferative DR?
Should non-proliferative DR without oedema be treated proactively?
What is the DRSS and why does it matter?
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