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TB-500: evidence brief

Selected primary studies, with the material tested, findings and limitations kept together. Follow each source to understand what it establishes.

TB-500: evidence brief

One label can hide different molecules

Read the study material before carrying a finding across to TB-500. These three categories are kept separate in the brief.

Defined fragment

Ac-LKKTETQ · 7 amino acid residues

Ac = N-terminal acetyl group, not an eighth residue.

The laboratory/metabolism paper tests this fragment and metabolite standards. Its cell finding concerns Ac-LKKTE.

Read the study and its limits: Defined fragment ↓

Sequence-length schematics, not three-dimensional structures or relative efficacy. They do not authenticate a commercial product.

Peptides Codex

What was actually studied

The defined fragment has laboratory/metabolism evidence; the rat tendon result concerns incompletely characterized TB-500-labelled material. A human eye trial studied full-length thymosin β4, so it cannot validate the fragment or injectable TB-500.

Version
2026-10-05.1
Snapshot updated

Prepared by Peptides Codex. Independent review by a qualified subject specialist is pending.

Scope of this brief

The selected profile reference is Ac-LKKTETQ, the N-acetylated seven-residue thymosin β4 fragment. Full-length 43-residue thymosin β4 and unspecified TB-500-labelled materials are separate evidence categories. This selected synthesis is not a systematic or independent expert review.

  1. Rahaman et al., 2024 · PMID 38382158

    Material tested
    Defined Ac-LKKTETQ and synthesized metabolite standards.
    Model or population
    Human serum/enzyme systems, rats and cultured fibroblasts.
    Study design
    Analytical/metabolism experiments and an in-vitro wound-closure screen.
    Sample and comparison
    Sample counts not reported in the retrieved abstract.
    Reported finding
    Ac-LKKTE, not parent Ac-LKKTETQ, significantly increased wound closure versus control in the cell assay.
    Limits of this evidence
    A cell assay and metabolism measurements do not establish tendon healing or clinical efficacy. Full methods were not retrieved.

    Source access: Primary abstract inspected; full-text methods unavailable during this review.

    Primary source ↗: Rahaman et al., 2024 · PMID 38382158

  2. Biçer et al., 2026 · PMID 42542926

    Material tested
    Authors' TB-500-labelled material; sequence not characterized as Ac-LKKTETQ.
    Model or population
    Rats after Achilles tendon transection and repair.
    Study design
    Randomized four-arm experiment including BPC-157 and a combination; four-week endpoint.
    Sample and comparison
    32 rats, 8/group; separate endpoint cohorts of 4/group.
    Reported finding
    TB-labelled material improved failure load versus control (adjusted p=0.0406); combination showed no added benefit.
    Limits of this evidence
    Cannot attribute this result to the selected Ac-LKKTETQ fragment. Small animal cohorts do not establish human benefit.

    Source access: Primary journal full text and PubMed abstract inspected.

    Primary source ↗: Biçer et al., 2026 · PMID 42542926

  3. Sosne & Ousler, 2015 · PMID 26056426

    Material tested
    RGN-259 ophthalmic full-length 43-residue thymosin β4, not Ac-LKKTETQ.
    Model or population
    Adults with moderate-to-severe dry eye.
    Study design
    Single-center randomized, double-masked, placebo-controlled phase II trial; 28 days.
    Sample and comparison
    72 randomized, 36/group; 69 completed.
    Reported finding
    Neither primary endpoint differed significantly; several secondary measures favored treatment.
    Limits of this evidence
    Different molecule, formulation and indication. Secondary findings cannot validate the fragment or injectable TB-500.

    Source access: Primary full-text sections retrieved in indexed results; PubMed abstract corroborated.

    Primary source ↗: Sosne & Ousler, 2015 · PMID 26056426

A finding applies to the material, model and conditions studied. It does not establish safety or effectiveness in other settings.

Help review this exact version

Qualified scientific review is pending. Source-backed corrections are welcome; a correction submission does not itself constitute expert approval.

Review reference: tb-500 · 2026-10-05.1

What a reviewer should check
  1. Does the reported material match the preparation actually studied?
  2. Do population, participant counts and analysis denominators match the source?
  3. Are estimates, endpoints, uncertainty and missing-data methods represented accurately?
  4. Do limitations, source-access boundaries and English/French text preserve the same conclusion?

Study records in this version

In your message, include this brief reference, the study identifier, the source citation and the proposed change. If offering scientific review, include your relevant specialty and conflicts of interest. Omit patient information and confidential research material.

Recording a qualified review requires verified qualifications, an agreed scope and approval of the identified version. Public reviewer attribution requires separate permission. Review status remains pending until that process is complete.

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