RGN-259 in dry eye
Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment model
Sosne G, Ousler GW · Clinical Ophthalmology
Study record
- Population
72 adults with moderate-to-severe dry eye, 36 per group; mean age 56.2 years. Eligibility required a response to a controlled adverse environment.
Read source · Full-text reportMaterials and methods — Study design; Table 1- Formulation
Synthetic 43-amino-acid thymosin-beta-4, purified and lyophilized as acetate salt; preservative-free sterile 0.1% w/w RGN-259 solution versus matching vehicle.
Read source · Full-text reportIntroduction; Materials and methods — preparation- Route
Topical instillation into each eye.
Read source · Full-text reportMaterials and methods — Study design- Dose & frequency
Reported treatment: 1–2 drops per eye twice daily for 28 days. This establishes no KLOW regimen and is not an injectable TB-500 protocol.
Read source · Full-text reportMaterials and methods — Study design- Study design
Phase 2, single-center, double-masked, randomized 1:1 against vehicle; efficacy analyzed using the worst eligible eye, safety using both eyes.
Read source · Full-text reportMaterials and methods; Safety analysis- Duration
28 days of treatment, with assessments through approximately day 30. This does not establish a repeating treatment cycle.
Read source · Full-text reportMaterials and methods — Study design; Figure 1- Reported findings
Neither primary day-29 endpoint was significant: inferior staining means 2.08 versus 1.90; discomfort 1.6 versus 1.3. Several secondary/ad hoc analyses favored treatment.
Read source · Full-text reportResults — Efficacy; Statistical analysis- Adverse events
Full Results reports ocular treatment-emergent events in 2/36 active versus 5/36 vehicle recipients, despite the abstract stating none. Events in active recipients were mild; long-term safety was not tested.
Read source · Full-text reportResults — safety findings; Abstract Results- Monitoring
Visual acuity, ocular examinations, pressure and sensitivity assessments; treatment-emergent events recorded through visit 6. These are study assessments, not a personal monitoring plan.
Read source · Full-text reportAbstract Methods; Materials and methods — Safety analysis
What it supports
Tests a specific ophthalmic thymosin-beta-4 formulation against vehicle. Neither primary endpoint was significant; secondary findings are exploratory context.
What it does not establish
Single-center, short-duration trial. Full-length thymosin-beta-4 is not the TB-500 fragment; ocular findings do not establish systemic or KLOW efficacy or safety. Abstract says no adverse events, but full Results reports ocular treatment-emergent events; the record uses the detailed Results. Registry NCT01387347 reports different nonserious-event counts (0/36 active, 2/36 placebo); these have not been reconciled with the publication’s 2/36 and 5/36 ocular-event counts.
Funding
Authors declared no conflicts in Disclosure. No explicit funding statement located in the inspected article; absence of a declaration is not proof of no sponsor involvement.
Literature search cutoff: 2026-09-08 · Not independently clinically reviewed
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