Human study PLS-00174

Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) model.

Randomized controlled trial · Not reported participants enrolled

Version 1 · published November 8, 2026 · evidence through November 8, 2026 · research snapshot 2026.1.1 · methodology ev-1 · Automated assessment by AI (claude-opus-5-5 and claude-sonnet-5-5), not reviewed by a person.

Only the abstract was available. Essential methods may be missing, which limits what can be judged.

Reports of this study

Every publication, registration and abstract describing this one study. Participants are counted once.

Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) model.primary · Clinical ophthalmology (Auckland, N.Z.) · 2015-05-20 · PMID 26056426 · DOI

Design and participants

Design: Randomized controlled trial
Population: Subjects with moderate to severe dry eye who qualified for a controlled adverse environment (CAE) challenge model study
Conditions: Dry eye disease (moderate to severe)
Setting: Single-center study using the controlled adverse environment (CAE) model
Planned enrollment (registry): Not reported
Enrolled: Not reported
Randomized: 72
Completed follow-up: Not reported
Funding: Not stated in the record
Authors’ conflicts: Not stated in the record

Intervention and comparator

What each group received. Related peptides, analogs and combinations are never treated as the compound itself.

Tβ4 ophthalmic solution (intervention) · thymosin-beta-4 · Thymosin beta 4 ophthalmic solution (RGN-259) · topical ophthalmic · 28 days of treatment within a 32-day study period · Not reported assigned
Placebo (comparator) · Placebo ophthalmic treatment · placebo · topical ophthalmic · 28 days of treatment within a 32-day study period · Not reported assigned

What the authors reported

As stated in the sources. This is the authors’ account, not Peptide Library’s assessment.

Ocular discomfort score

primary outcome · patient-important · Visit 5, day 29 · Ocular discomfort score

Tβ4 ophthalmic solution vs Placebo: narrative — No significant difference between treatment and control groups at visit 5

Inferior corneal staining

primary outcome · surrogate · Visit 5, day 29 · Inferior corneal staining score

Tβ4 ophthalmic solution vs Placebo: narrative — No significant difference between treatment and control groups at visit 5

Ocular discomfort during CAE challenge

secondary outcome · patient-important · Day 28 CAE visit · Discomfort scores in the controlled adverse environment

Tβ4 ophthalmic solution vs Placebo: other, p = 0.0244 — Discomfort scores in the CAE were reduced by 27% with Tβ4 compared with placebo

Central corneal staining

secondary outcome · surrogate · Not stated in abstract · Central corneal staining score

Tβ4 ophthalmic solution vs Placebo: narrative, p = 0.0075 — Statistically significant improvement in central corneal staining versus control

Superior corneal staining

secondary outcome · surrogate · Not stated in abstract · Superior corneal staining score

Tβ4 ophthalmic solution vs Placebo: narrative, p = 0.021 — Statistically significant improvement in superior corneal staining versus control

Conjunctival staining

secondary outcome · surrogate · Not stated · Conjunctival staining score

No results reported.

Conjunctival redness

secondary outcome · surrogate · Not stated · Conjunctival redness score

No results reported.

Tear film break-up time

secondary outcome · surrogate · Not stated · Tear film break-up time

No results reported.

Daily symptom scores

secondary outcome · patient-important · Throughout study · Daily symptom scores recorded over the course of the study

No results reported.

Adverse events

secondary outcome · safety · Over the 32-day study period · Adverse events, plus safety measures including visual acuity, slit-lamp examination, intraocular pressure, dilated funduscopy and corneal sensitivity

Tβ4 ophthalmic solution vs Placebo: narrative — No adverse events were observed or reported by any subject

Adverse events

None reported. That is not evidence of safety.

Monitoring: Visual acuity, slit-lamp evaluation, conjunctival redness, tear film break-up time, intraocular pressure, dilated funduscopy and corneal sensitivity were assessed across six visits over 32 days.

The authors concluded (paraphrased): The authors concluded that topical Tβ4 is effective for relieving signs and symptoms of dry eye and has a large safety window, with no adverse events reported. This was despite both primary endpoints showing no significant difference.

Peptide Library’s assessment

An automated assessment, made by AI separately from the authors’ conclusions and not reviewed by a person. How risk of bias is assessed.

Limitations

selective reporting: Both primary endpoints were null, yet the conclusion rests on selected significant secondary endpoints, with no stated adjustment for multiplicity.
small or imprecise: Only 72 subjects were randomized at a single center, and no effect sizes with confidence intervals are reported in the abstract.
short follow up: Treatment lasted 28 days within a 32-day study, so durability of effect and longer-term safety are unknown.
other: The controlled adverse environment challenge model is an artificial setting that may not reflect everyday dry eye symptoms.
abstract only: Only the abstract was available, so randomization methods, attrition, group sizes and analysis populations cannot be verified.
funding or conflicts: Funding and conflicts are not reported in the record, although the product code RGN-259 suggests a commercial sponsor.
inappropriate endpoint: Both primary endpoints (discomfort and inferior corneal staining at day 29) showed no significant difference; the benefits are in secondary endpoints, and multiplicity is not addressed.

Ocular discomfort score: Some concerns (Cochrane RoB 2)