Human study PLS-00201

Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.

Randomized controlled trial · 9 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 β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.primary · Cornea · 2015-05-01 · PMID 25826322 · DOI
Comparative Study of Thymosin Beta 4 Eye Drops vs. Vehicle in the Treatment of Severe Dry Eyeregistry entry · NCT01393132 (COMPLETED, results posted, planned enrollment 9)

Design and participants

Design: Randomized controlled trial
Population: Patients with severe dry eye disease, including dry eye associated with graft vs. host disease. The registry also lists Sjogren's syndrome as a condition.
Conditions: Severe dry eye disease, Graft vs. host disease, Sjogren's syndrome
Setting: Multicenter trial at 2 US sites. Treatment lasted 28 days with a further 28-day follow-up, for 56 days in total. (United States)
Planned enrollment (registry): Not reported
Enrolled: 9
Randomized: Not reported
Completed follow-up: Not reported
Funding: PubMed lists the publication type as Research Support, Non-U.S. Gov't. The funder is not named in the record.
Authors’ conflicts: Not reported in the record.

Intervention and comparator

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

RGN-259 (thymosin beta-4 eye drops) (intervention) · thymosin-beta-4 (formulation) · Thymosin beta-4 ophthalmic eye drop formulation (RGN-259) · topical ocular · 28 days of treatment, then 28-day follow-up (to day 56) · Not reported assigned
Vehicle control (comparator) · Vehicle eye drops without thymosin beta-4 · placebo · topical ocular · 28 days of treatment, then 28-day follow-up (to day 56) · Not reported assigned

What the authors reported

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

Ocular discomfort (OSDI questionnaire)

unclear outcome · patient-important · Various time points; highlighted at day 56 (28 days post-treatment) · Ocular Surface Disease Index questionnaire

RGN-259 (thymosin beta-4 eye drops) vs Vehicle control: other 35.1, p = 0.0141 — At day 56, ocular discomfort was reduced by 35.1% versus vehicle (12 treated eyes vs 6 vehicle eyes).

Total corneal fluorescein staining

unclear outcome · surrogate · Various time points; highlighted at day 56 · NEI workshop grading system

RGN-259 (thymosin beta-4 eye drops) vs Vehicle control: other 59.1, p = 0.0108 — At day 56, total corneal fluorescein staining was reduced by 59.1% versus vehicle (eye-level comparison).

Tear film breakup time

unclear outcome · surrogate · Not stated · Not described

RGN-259 (thymosin beta-4 eye drops) vs Vehicle control: narrative — Improvement in tear film breakup time was reported in treated patients; no figures were given.

Tear volume production

unclear outcome · surrogate · Not stated · Not described

RGN-259 (thymosin beta-4 eye drops) vs Vehicle control: narrative — Increased tear volume production was reported in treated patients; no figures were given.

Safety and tolerability

unclear outcome · safety · Over the 56-day study · Not described

RGN-259 (thymosin beta-4 eye drops): narrative — The eye drops were described as safe and well tolerated; no adverse event counts were given.

Adverse events

None reported. That is not evidence of safety.

Monitoring: The abstract states the trial evaluated safety and that RGN-259 was safe and well tolerated. Monitoring methods and adverse event data are not reported.

The authors concluded (paraphrased): In this small trial, RGN-259 eye drops were safe and well tolerated. They met key efficacy objectives, with statistically significant improvements in symptoms and signs versus vehicle at various time points, including 28 days after treatment ended.

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

small or imprecise: Only 9 patients were enrolled (12 treated eyes vs 6 vehicle eyes), and no confidence intervals are reported.
selective reporting: Significant differences are reported only 'at various time points'. Day 56 results are singled out, and results for the other time points are not given.
other: Safety is summarized only as 'safe and well tolerated', with no adverse event counts or discontinuations reported.
abstract only: Appraisal relies on the PubMed abstract and registry fields only. Randomization, allocation concealment and attrition details are unavailable.
short follow up: Total follow-up was 56 days, covering 28 days of treatment and 28 days post-treatment, which is short for a chronic condition.
funding or conflicts: Funding and conflict of interest are not stated in the record.

Ocular discomfort (OSDI questionnaire): High risk of bias (Cochrane RoB 2)