Peptide education
Thymosin beta-4
Tbeta4 · TB4 · Timbetasin · Thymosin beta 4
Thymosin beta-4 is a 43-amino-acid peptide your body already makes, best known in the lab for sequestering actin and helping cells migrate into wounds. It is one of the few gray-market peptides with a genuine clinical development history: randomized eye-drop trials in dry eye and neurotrophic keratopathy, older topical gel studies in chronic wounds, and short IV safety studies. Almost none of that history touches what people actually buy it for. The tendon, muscle, and return-to-training claims come from the market, and the vials sold for those uses are usually fragments or worse, not the full-length protein the trials studied.
The real human evidence for thymosin beta-4 is an eye-drop program, some older wound gels, and short IV safety studies. The recovery-injection market uses the name and skips the evidence.
Overview
Quick answer
Full-length thymosin beta-4 is also called Tbeta4 or timbetasin in some development contexts. TB-500 usually points to the shorter Ac-LKKTETQ fragment or to an inconsistent gray-market product name. Full-length Tbeta4 studies cannot be used as evidence for every TB-500 vial.
What is thymosin beta-4?
A full-length, 43-amino-acid beta-thymosin found throughout mammalian tissues. Its signature job is binding monomeric actin, which puts it upstream of cell migration, angiogenesis, and wound-response biology, and that is why repair researchers took an interest.
What do people use it for or talk about?
Two conversations run in parallel. The clinical one tested eye drops for dry eye and neurotrophic keratopathy, topical gels for venous and pressure ulcers, and IV dosing for safety. The market one sells injections for tendon repair, muscle recovery, anti-aging, and skin, usually under TB-4 or TB-500 language. Only the first conversation has human trials in it.
What route, amount, and schedule details are reported?
The human studies used 0.1% eye drops several times daily for 28 days, topical dermal gel once daily for up to 84 days, and IV dosing over 14 days across a 42 mg to 1260 mg range. The community recovery pattern, 2 to 5 mg per week subcutaneously for 4 to 8 weeks, comes from forums and clinics and was never tested in the cited human work.
Why is TB-500 a problem here?
Because TB-500 is usually a shorter fragment (Ac-LKKTETQ) or an inconsistent market label, not the 43-amino-acid protein the trials used. Analytical work has found misbranded and adulterated TB500/TB1000 products. Evidence from the full-length protein does not transfer to a fragment vial, and treating the two names as interchangeable is the main way this record gets inflated.
What does the evidence show about recovery claims?
Nothing direct. Actin biology and animal wound work make systemic recovery plausible enough to study, but the human studies are ophthalmic, topical dermal, or short IV safety work. No cited human trial tested injected thymosin beta-4 for tendon, muscle, or training recovery.
Reported practice
Commonly reported protocol
Community full-length Tb4 protocols. Community-reported patterns, not verified by controlled human trials and not a use recommendation. Full use-pattern detail
Evidence
Evidence snapshot
RGN-259 and topical thymosin beta-4 eye-drop studies provide the clearest human signal, especially dry eye and neurotrophic keratopathy work. The results are suggestive but still investigational, with mixed dry-eye phase III history and no FDA approval found.
Venous-ulcer, pressure-ulcer, and epidermolysis bullosa material suggests development activity and a possible topical wound signal, but the public record is limited and uneven.
Phase I IV studies help with narrow tolerability context for studied full-length products. They are not benefit data for generalized recovery, tendon repair, muscle injury, or anti-aging use.
TB-500 is commonly tied to a shorter fragment or inconsistent market label. Analytical sources report misbranding and adulteration in TB500/TB1000 products, so a vendor name or COA still leaves the key question open: full-length Tbeta4, a fragment, a metabolite, or something mislabeled.
FDA orphan designation for neurotrophic keratopathy does not equal approval, and FDA warning-letter language has treated marketed thymosin beta-4 products as unapproved drugs and biological products.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Anecdotal evidence | Verdict |
|---|---|---|---|---|
| Thymosin beta-4 helps heal the ocular surface. | The strongest human area here is topical ophthalmic use. Dry-eye and neurotrophic keratopathy studies used thymosin beta-4 or RGN-259 eye drops, including 0.1% solution schedules over 28 days. SEER-1 reported complete healing at Day 29 in 6 of 10 treated participants versus 1 of 8 on vehicle, with small-sample limitations. | The mechanism fits ocular-surface repair: epithelial migration, inflammation modulation, cell-matrix interaction, and barrier recovery are all tied to thymosin beta-4 biology. | Online recovery discussions usually pay less attention to the eye-drop route, but the ophthalmic studies are more relevant than forum recovery claims when evaluating actual human evidence. | Plausible and supported by the best human evidence, but still investigational and route-specific. |
| Thymosin beta-4 works for tendon, muscle, or training-injury recovery. | The available human studies do not make that case. They mostly cover ophthalmic use, topical dermal wounds, and short-term IV safety. | Actin binding, migration, angiogenesis, and wound-response biology explain the recovery rationale. What is missing is controlled human injury data for the recovery claims. | Clinics, vendors, online regimen pages, and forums commonly talk about recovery, soft-tissue repair, and TB-500-style healing. Those reports can show the recovery market, but they cannot show that a full-length Tbeta4 product repairs human tendons or muscles. | Overstated. The claim is common online, but the available human evidence is too narrow for it. |
| TB-500 has the same evidence as full-length thymosin beta-4. | No. Most human thymosin beta-4 sources describe full-length products and routes such as ophthalmic, topical dermal, or IV. FDA and analytical sources discuss TB-500 around a shorter fragment or inconsistent product labels. | Fragment activity can explain why TB-500 became attractive, but changing the molecule can change pharmacology, metabolism, exposure, safety, and product identity. | Gray-market listings often blur TB-4, thymosin beta-4, TB-500, fragments, and metabolites. Analytical work has found misbranded or adulterated products in this category. | Full-length Tbeta4 evidence does not establish the effects of TB-500 fragments or market products. Eye-drop and topical-wound studies do not support claims for an injected recovery vial. |
| Thymosin beta-4 has human chronic-wound evidence. | Limited. Older topical dermal studies and registry material cover venous ulcers, pressure ulcers, and epidermolysis bullosa, with once-daily gel schedules reported for up to 84 days in some wound contexts. The public evidence is less complete than the ophthalmic evidence. | Epithelial and endothelial migration, angiogenesis, and matrix interaction are the basis for wound research. | Online users often convert wound-healing language into generalized recovery claims. That leap is larger than the actual topical wound sources. | Reasonable to mention as limited investigational wound evidence, not as evidence of broad systemic healing. |
| Thymosin beta-4 is safe because it occurs naturally in the body. | Short-term IV and ophthalmic studies are somewhat reassuring in their own settings, but they do not settle long-term systemic exposure, reproductive safety, cancer-adjacent concerns, fragment safety, or gray-market injection use. | Repair, angiogenesis, and migration biology create theoretical concerns for chronic systemic use near pro-growth disease states, even though the available human studies have not identified that harm. | Market pages and user discussions may use "natural" as comfort language. That does not settle sterility, endotoxin, identity, concentration, impurity, or route-specific safety questions. | Too simple. Safety depends on molecule, route, duration, product quality, and patient context. |
Bottom line
Main takeaway
Thymosin beta-4 is a real repair peptide with real human trials, but those trials are eye drops and wound gels, not recovery injections. The "healing peptide" reputation runs far ahead of the studied uses.
Three questions sort every claim: full-length protein or TB-500 fragment, which route was studied, and does the product have credible identity and sterility documentation. Most market claims fail at least one.
Start with the ophthalmic trials (RGN-259, SEER-1, the CAE dry-eye study), then the topical wound studies and IV phase I safety work, then FDA and analytical sources on TB-500 product identity.
Identity
What it is
Thymosin beta-4 is a 43-amino-acid peptide present in most mammalian cells, and one of the body's main G-actin-sequestering molecules. That single function, controlling the structural protein cells use to move, puts it inside wound closure, epithelial migration, blood-vessel formation, and inflammation signaling.
A real drug-development effort grew out of that biology. RGN-259 was the eye-drop program, RGN-137 the dermal wound gel, RGN-352 the systemic candidate. The eye program produced the best data: small randomized trials in dry eye and neurotrophic keratopathy, including SEER-1, where 6 of 10 treated patients healed their corneal defects completely at Day 29 versus 1 of 8 on vehicle, in a sample too small to settle anything. FDA granted orphan designation for neurotrophic keratopathy; approval never followed, and the dry-eye phase III history was mixed.
The wound and systemic programs were thinner: older gel studies in venous and pressure ulcers with limited public reporting, an epidermolysis bullosa study that missed its Day 56 endpoint, and phase I IV studies that established short-term tolerability and nothing about efficacy.
None of this is what the peptide market sells. The vials marketed as TB-4 or TB-500 for tendon and muscle recovery are typically fragments or unverified material, and the subcutaneous recovery cycles circulating online were never part of the clinical program. The studied molecule and the sold molecule part company right at the label.
How people talk about it online
Forum and clinic talk centers on tendon and muscle repair, faster return to training, skin healing, and stacks with BPC-157. The usual schedule described is 2 to 5 mg per week subcutaneously, split into one or two injections, for 4 to 8 weeks. No human study tested that pattern; it borrows the molecule's research reputation wholesale.
The naming is genuinely slippery in this corner of the market. TB-4, thymosin beta-4, TB-500, and fragment names get used interchangeably on vendor pages, and analytical studies have documented misbranded and adulterated TB500/TB1000 products. A COA describing one sample does not establish sterility, concentration, or even which molecule is in the vial.
The result is a market that talks in the grammar of the clinical program (repair, healing, regeneration) while selling products the clinical program never used, for routes it never studied.
Use context
Routes, doses, and cycle patterns
The human thymosin beta-4 patterns in the cited sources are mostly ophthalmic, topical dermal, or IV. Online recovery patterns are often subcutaneous or intramuscular and are commonly tied to TB-500 language. The cited human studies do not test those online recovery routes or cycles.
Human studies and product labels
IV phase I full-length thymosin beta-4
- Purpose
- Short-term systemic safety in healthy volunteers
- Context
- Randomized placebo-controlled phase I study
- Route
- IV
- Amount
- 42 mg to 1260 mg range
- Frequency
- Single and multiple daily dosing described in the source
- Duration
- Over 14 days
This supports narrow short-term tolerability context for studied full-length IV thymosin beta-4. It is not efficacy evidence or a general recovery schedule.
Recombinant human thymosin beta-4 phase I
- Purpose
- Safety, pharmacokinetics, and anti-drug-antibody context
- Context
- First-in-human randomized double-blind phase I study
- Route
- IV
- Amount
- Dose detail not available in the public abstract.
- Frequency
- Single- and multiple-dose study
- Duration
- Not reported in the public source
This adds systemic safety context, but public sources lack enough detail to support more than route and study type.
Severe dry eye RGN-259 phase II study
- Purpose
- Ophthalmic symptoms and signs in severe dry eye
- Context
- Small randomized phase II trial
- Route
- Topical ophthalmic
- Amount
- 0.1% RGN-259 ophthalmic solution
- Frequency
- Six times daily
- Duration
- 28 days
The 9-patient study reported significant differences in signs and symptoms at several time points. The sample size keeps it from being a definitive dry-eye answer.
Moderate-to-severe dry eye CAE trial
- Purpose
- Dry-eye signs and symptoms under controlled adverse-environment testing
- Context
- Randomized double-masked placebo-controlled phase II trial
- Route
- Topical ophthalmic
- Amount
- 0.1% thymosin beta-4 ophthalmic solution
- Frequency
- 1 to 2 drops in each eye twice daily
- Duration
- 28 days
Primary endpoints were not significant, but several secondary endpoints improved, including discomfort and corneal staining measures. Safety reporting was generally reassuring in this short trial.
Neurotrophic keratopathy SEER-1
- Purpose
- Healing persistent corneal epithelial defects
- Context
- Randomized placebo-controlled double-masked study
- Route
- Topical ophthalmic
- Amount
- 0.1% RGN-259 ophthalmic solution
- Frequency
- Five times daily
- Duration
- 28 days
Complete healing at Day 29 was reported in 6 of 10 treated participants versus 1 of 8 on vehicle, with a small orphan-disease sample and a narrowly missed Day 29 statistical result.
Venous ulcer topical gel study
- Purpose
- Chronic dermal wound healing
- Context
- Phase II multicenter randomized dose-response study
- Route
- Topical dermal
- Amount
- 0.01%, 0.03%, and 0.1% topical gel cohorts
- Frequency
- Once daily
- Duration
- Up to 84 days
Public summaries suggest the 0.03% cohort was the most active dose and shortened healing time relative to comparison arms, but public primary reporting remains limited.
Pressure ulcer topical gel registry
- Purpose
- Chronic wound-healing development context
- Context
- ClinicalTrials.gov phase II registry record
- Route
- Topical dermal
- Amount
- Not reported in the cited registry summary
- Frequency
- Once daily
- Duration
- Up to 84 days
The registry documents study context and a topical schedule, not a public efficacy conclusion without posted results.
Epidermolysis bullosa topical study
- Purpose
- Junctional and dystrophic epidermolysis bullosa wound context
- Context
- Phase II study with secondary public reporting
- Route
- Topical dermal
- Amount
- 0.01%, 0.03%, and 0.10% topical doses reported secondarily
- Frequency
- Not reported in the public source
- Duration
- Day 56 endpoint discussed in secondary reporting
Secondary reporting says the Day 56 healing endpoint was not met, with ad hoc Day 14 trends favoring active treatment. The available trial summaries did not include a primary result source.
Real-world discussion
Community full-length Tb4 protocols
- Purpose
- Recovery and cardiac-adjacent discussion
- Context
- Forums, clinics, and vendor listings
- Route
- Subcutaneous injection
- Amount
- Community use is usually described as 2 to 5 mg per week, split across one or two injections
- Frequency
- Once or twice weekly in most descriptions
- Duration
- Usually 4 to 8 week runs
Full-length thymosin beta-4 has a genuine research literature but no established human self-use protocol; community schedules borrow from animal and cell work. Many products sold as TB-500 are fragments rather than the full-length protein. Shared here as context, not instruction.
What varies
- Molecule: full-length thymosin beta-4, RGN-259, RGN-137, recombinant Tbeta4, TB-500, and Ac-LKKTETQ have different evidence records and product identities.
- Route: ophthalmic, topical dermal, IV, subcutaneous, and intramuscular use create different exposure and safety questions.
- Goal: ocular-surface healing, chronic dermal wounds, systemic safety, tendon repair, muscle recovery, and anti-aging are different claims.
- Product quality: identity, sterility, endotoxin, assay, impurities, concentration after reconstitution, storage, and shipping conditions matter for any non-approved injectable product.
Human data
Human evidence
The human record is real but concentrated. The strongest area is ophthalmology: randomized 0.1% eye-drop trials in dry eye and neurotrophic keratopathy, with SEER-1 showing a small healing signal (6 of 10 versus 1 of 8) that narrowly missed conventional significance. Older topical gel studies in venous ulcers, pressure ulcers, and epidermolysis bullosa are weaker and incompletely reported, and the bullosa endpoint was missed. Two phase I IV studies document short-term tolerability across 42 mg to 1260 mg over 14 days, with no efficacy endpoints. Nothing in the human record tests the injected recovery use the market is built on.
Evidence maturity
Full-length thymosin beta-4 has real but narrow human development, concentrated in ophthalmic use, and never reached approval while gray-market TB-500 products trade on its name.
Actin sequestration, cell migration, angiogenesis, and wound-response work established the repair rationale in lab models.
Phase I IV safety work, phase II ophthalmic trials, and topical dermal wound studies supplied the first human exposure data.
SEER-1 showed a small neurotrophic-keratopathy healing signal while dry-eye phase III history and the epidermolysis-bullosa endpoint were mixed or missed.
FDA orphan designation for neurotrophic keratopathy exists, but no thymosin beta-4 product is approved and the programs remain investigational.
Gray-market TB-500 fragments borrow the full-length evidence, with documented misbranding and FDA safety-risk flags.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| IV phase I full-length thymosin beta-4 | Healthy volunteers | Randomized placebo-controlled phase I safety study | Synthetic full-length thymosin beta-4 | Public summaries reported tolerability across a 42 mg to 1260 mg IV exposure range over 14 days, without dose-limiting toxicity or serious adverse events. | Safety only, short-term, IV route, and no efficacy endpoint for injury recovery or chronic use. | Limited human |
| Recombinant human thymosin beta-4 phase I | Healthy Chinese volunteers | First-in-human randomized double-blind phase I study | Recombinant human thymosin beta-4 | The study summary reported short-term tolerability, with pharmacokinetic and anti-drug-antibody context. | The public abstract does not give enough dose detail to compare it with other routes or study patterns, and this was not an efficacy study. | Limited human |
| Severe dry eye RGN-259 phase II | People with severe dry eye | Small randomized phase II trial | 0.1% RGN-259 ophthalmic solution | A 9-patient study reported significant differences in several signs and symptoms across time points after six-times-daily use for 28 days. | Very small sample size and not definitive for approval or broad eye-disease use. | Limited human |
| Moderate-to-severe dry eye CAE trial | People with moderate to severe dry eye studied in a controlled adverse-environment model | Randomized double-masked placebo-controlled phase II trial | 0.1% thymosin beta-4 ophthalmic solution | Primary endpoints were not significant, but several secondary endpoints improved, including discomfort and corneal staining measures. | Mixed endpoint pattern, short duration, and route-specific ophthalmic context. | Limited human |
| Chronic nonhealing neurotrophic corneal epithelial defects | Patients with neurotrophic corneal epithelial defects | Compassionate-use / open clinical report | Topical thymosin beta-4 sterile eye drops | Geographic defects showed dramatic healing in several patients during 28- or 49-day treatment periods. | Uncontrolled, very small, and heterogeneous. | Anecdotal human |
| SEER-1 neurotrophic keratopathy trial | People with stage 2 to 3 neurotrophic keratopathy | Randomized placebo-controlled double-masked study | 0.1% RGN-259 ophthalmic solution | Complete healing at Day 29 was reported in 6 of 10 treated participants versus 1 of 8 on vehicle, with benefit persisting at Day 43 and comfort endpoints also improving. | Small orphan-disease sample and the Day 29 primary comparison narrowly missed conventional significance in the published report. | Moderate human |
| Venous ulcer topical gel study | People with venous ulcers | Phase II multicenter randomized dose-response study | Topical thymosin beta-4 gel | Public summaries suggest the 0.03% dose was the most active and shortened healing time relative to comparison arms. | Public reporting is limited, and a topical wound signal cannot be used to predict systemic tendon, muscle, or anti-aging effects. | Weak human |
| Pressure ulcer topical gel registry | People with pressure ulcers | Phase II multicenter randomized dose-response registry context | Topical thymosin beta-4 gel | The trial was registered and completed, with once-daily topical use up to 84 days described in the available trial summaries. | Public primary results were not found in the cited sources. | Weak human |
| Epidermolysis bullosa topical study | People with junctional or dystrophic epidermolysis bullosa | Phase II study with secondary reporting | Topical thymosin beta-4 | Secondary reporting says the Day 56 healing endpoint was not met, though ad hoc Day 14 trends favored active treatment. | Primary results were not found. | Weak human |
Cautions
Safety and unknowns
- Short IV phase I studies and topical ophthalmic trials do not answer long-term systemic safety.
- Reproductive, pregnancy, lactation, and pediatric safety remain unanswered for non-approved uses in the current evidence.
- Cancer-adjacent concern remains theoretical but relevant because the biology involves cell migration, angiogenesis, and repair signaling; the available human studies do not settle long-term risk in pro-growth contexts.
- The safety record for TB-500 fragment products is weaker than the full-length Tbeta4 record. FDA materials say the fragment lacks human exposure data and flag immunogenicity and impurity concerns.
- Informal subcutaneous or intramuscular recovery patterns create different risks than studied ophthalmic, topical dermal, or IV products.
Product quality
A vial label is only a starting point
Product identity is the first issue: full-length thymosin beta-4, Ac-LKKTETQ, TB-500, metabolites, and mislabeled market products can be blurred in vendor and forum discussion.
A COA can report a narrow assay result for a submitted sample. It does not by itself stand in for sterility, endotoxin control, finished-product concentration, storage stability, degradation profile, fill accuracy, or chain of custody.
Unauthorized injectable peptide alerts and TB500/TB1000 analytical work make product-quality risk central, not a side issue.
Molecule identity
Full-length Tbeta4 evidence does not identify the peptide inside a TB-500 vial or show that it is sterile, correctly concentrated, or clinically equivalent.
Sterility and endotoxin
Injectable products can be contaminated even when a purity percentage looks reassuring.
Concentration and dose math
Reconstitution, fill amount, assay accuracy, and labeling affect the amount actually delivered.
Stability and storage
Peptide degradation, shipping conditions, freeze-thaw history, and storage instructions can change product reliability.
COA scope
A COA can support a narrow batch claim, but it does not stand in for sterility, stability, or full pharmaceutical manufacturing controls.
Mechanism
How it is proposed to work
Thymosin beta-4 helps cells handle actin, a structural protein that cells use to move and change shape. That matters for repair because wound closure, epithelial migration, endothelial activity, and inflammation control all depend on coordinated cell movement and signaling.
Mechanism papers tie full-length Tbeta4 to G-actin sequestration, migration, angiogenesis, laminin-related matrix biology, and repair-associated signaling.
Ocular studies connect thymosin beta-4 with corneal epithelial recovery, reduced inflammatory mediator expression, matrix metalloproteinase changes, and improved cell-matrix interactions after stress.
Active fragments such as Ac-SDKP and the 17-23 LKKTETQ region help explain why fragment products entered the discussion, but fragment activity is not the same as evidence that TB-500 behaves like full-length Tbeta4 in people.
Thymosin beta-4 is a 43-amino-acid actin-sequestering protein with additional pro-angiogenic and anti-inflammatory activity in cardiac and dermal models. Anti-doping laboratories detect it by LC-MS, which is why it is a named prohibited substance rather than a gray-area one.
FAQ
Common questions
Is thymosin beta-4 the same thing as TB-500?
No. Full-length thymosin beta-4 and TB-500/Ac-LKKTETQ are separate materials. TB-500 identity or animal data are not enough to say full-length thymosin beta-4 works in people.
Do trial registries show thymosin beta-4 works for recovery?
No. Trial registries show that full-length thymosin beta-4 has been studied in specific clinical settings, but registry presence without published results is not enough for recovery, performance, or personal-use benefit claims.
What routes and schedules are actually documented?
Documented patterns include ophthalmic, topical dermal, and IV study use, plus injection-centered market discussion. Those patterns do not become a recovery protocol or product recommendation.
Details
Technical details
Sources
References
- 1.
ClinicalTrials.gov. ClinicalTrials.gov record NCT00382174 2006.
NCT00382174 Accessed 2026-06-08.
Full-length thymosin beta-4 trial record; adjacent to TB-500 fragment discussion, not interchangeable evidence.
- 2.
ClinicalTrials.gov. ClinicalTrials.gov record NCT00832091 2009.
NCT00832091 Accessed 2026-06-09.
Full-length thymosin beta-4 phase 2 venous stasis ulcer registry record; no posted results were used for efficacy conclusions.
- 3.
ClinicalTrials.gov. ClinicalTrials.gov record NCT00598871 2008.
NCT00598871 Accessed 2026-06-09.
Full-length thymosin beta-4 phase 2 corneal-wound registry record; terminated status and no posted results keep conclusions registry-bound.
- 4.
ClinicalTrials.gov. ClinicalTrials.gov record NCT05485818 2022.
NCT05485818 Accessed 2026-06-09.
Full-length thymosin beta-4 acute myocardial infarction phase 2 registry record; a registry listing maps the study rather than the clinical result.
- 5.
PMID:38382158 Accessed 2026-06-08.
In vitro and rat source; supports identity/activity mapping, not direct human exposure or efficacy.
- 6.
FDA. Compounding and the FDA: Questions and Answers 2026.
Accessed 2026-06-08.
FDA explains that compounded drugs are not FDA-approved and that FDA does not verify their safety, effectiveness, or quality before marketing.
- 7.
PubMed. Ruff et al., phase I IV full-length thymosin beta-4 in healthy volunteers 2010.
Accessed 2026-06-14.
Short-term systemic phase I safety source; IV dose range 42 mg to 1260 mg over 14 days.
- 8.
PubMed. Wang et al., first-in-human recombinant human thymosin beta-4 phase I 2026.
Accessed 2026-06-14.
Recombinant IV safety, pharmacokinetic, and anti-drug-antibody source.
- 9.
PubMed. Sosne et al., severe dry eye phase II randomized trial of RGN-259
Accessed 2026-06-14.
Nine-patient ophthalmic efficacy-signal source; 0.1% RGN-259 six times daily for 28 days.
- 10.
PubMed. Sosne and Ousler, Clinical Ophthalmology 2015 dry-eye CAE trial 2015.
Accessed 2026-06-14.
Moderate-to-severe dry-eye CAE trial with twice-daily dosing, mixed endpoints, and safety details.
- 11.
PubMed. Dunn et al., chronic nonhealing neurotrophic corneal epithelial defects
Accessed 2026-06-14.
Compassionate-use and open ocular-healing evidence.
- 12.
PubMed. Sosne et al., SEER-1 neurotrophic keratopathy trial
Accessed 2026-06-14.
SEER-1 source: 0.1% RGN-259 five times daily for 28 days, 6/10 versus 1/8 healing, and adverse-event profile.
- 13.
Other. Venous ulcer thymosin beta-4 topical gel study and record
Accessed 2026-06-14.
Topical dermal regimen, chronic wound signal, once daily up to 84 days.
- 14.
ClinicalTrials.gov. Pressure-ulcer thymosin beta-4 ClinicalTrials.gov record
Accessed 2026-06-14.
Registered topical wound-healing trial, once daily up to 84 days.
- 15.
Other. Epidermolysis bullosa thymosin beta-4 secondary reporting and trial registry listing
Accessed 2026-06-14.
Thirty-patient EB study note; primary endpoint reportedly not met.
- 16.
ClinicalTrials.gov. ClinicalTrials.gov and company dry-eye / neurotrophic keratopathy status sources
Accessed 2026-06-14.
ARISE and SEER development status, mixed phase III dry-eye history, and SEER-2 status.
- 17.
FDA. FDA orphan designation page for thymosin beta-4 in neurotrophic keratopathy
Accessed 2026-06-14.
Orphan designation for neurotrophic keratopathy; not FDA approved for the orphan indication.
- 18.
FDA. FDA warning letter, GenoGenix
Accessed 2026-06-14.
FDA warning letter framing thymosin beta-4 products as unapproved new drugs and biological products.
- 19.
FDA. FDA compounding safety-risks page for thymosin beta-4 fragment LKKTETQ / TB-500
Accessed 2026-06-14.
TB-500 fragment risk, immunogenicity concern, and no human exposure data found in the FDA material.
- 20.
FDA. FDA 503A bulk-substance requirements
Accessed 2026-06-14.
COA and supplier/manufacturing requirements in lawful compounding.
- 21.
Other. Analytical research snippets on TB-500 identity confusion
Accessed 2026-06-14.
TB-500 identity confusion, metabolite identification, and mislabeled products.
- 22.
PubMed. Drug Testing and Analysis internet-product analysis of TB500/TB1000 products
Accessed 2026-06-14.
Misbranded and adulterated TB500/TB1000 products.
- 23.
Other. Health Canada peptide alerts
Accessed 2026-06-14.
Unauthorized injectable peptide risk and lack of assessed safety, efficacy, or quality.
- 24.
PubMed. Sosne et al., active sites in short peptide sequences of thymosin beta-4
Accessed 2026-06-14.
Full-length biology and fragment mapping.
- 25.
PubMed. Esposito et al., Ac-LKKTETQ in TB-500
Accessed 2026-06-14.
Structural definition of the TB-500-associated fragment.
- 26.
PubMed. Philp et al., actin-binding site and angiogenesis in thymosin beta-4
Accessed 2026-06-14.
Mechanism source for migration and angiogenesis.
- 27.
PubMed. Philp et al., dermal wound repair with thymosin beta-4 and synthetic peptide
Accessed 2026-06-14.
Preclinical repair and fragment-relevance source.