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TB-500 Legit

A drafting-table readout of the TB-500 literature — every thymosin beta-4 finding dimensioned to its source, with the identity caveat, the regulatory standing and the sourcing due-diligence drawn to spec.

Original papers / 07 — follow a finding to its source

TB-500 references let you check who received treatment

Repair researchers used thymosin while trying to heal injuries. The shorter treatment wasn’t given in those tests. The papers let you check what happened.

Read the cell and animal resultsCheck the FDA notices

What a study number can help you find

Scientists testing thymosin beta-4 looked for repair in skin, hearts, and nerves. Most encouraging findings followed treatment with that larger protein. They didn't establish the same benefit from TB-500. Entries 1 through 17 cover experiments on the two treatments. They include the Phase 1 volunteer safety study and 2025-2026 work. Entries 18 through 22 concern FDA notices and pharmacy rules. Read those with the TB-500 pharmacy explanations.

You can look up a numbered claim in the list below.

Each title and link leads to a paper or trial listing. Long paper numbers help libraries find the study. Trial numbers identify plans filed in a public study list. Filing the plan doesn't mean the treatment worked or was approved. Look for the subjects’ details and the medicine they received. Thymosin beta-4 findings don't establish that the shorter treatment heals patients.

  1. TB-500 compound corpus (rev. 2): synthesis of the thymosin beta-4 / Ac-LKKTETQ research record, including the identity caveat (fragment ~889 Da vs full-length protein ~4963 Da), the absence of completed controlled clinical trials of the heptapeptide, the mdx muscular-dystrophy finding (regenerating fibers up, no strength gain), the porcine ischemia-reperfusion negative result, the medial collateral ligament rat finding, the hair-follicle stem-cell finding, the WADA-prohibited and detection context, and the research-grade purity concern. ↗
  2. Irobi E, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. ↗
  3. Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. ↗
  4. Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. ↗
  5. Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin β4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. ↗
  6. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks — entry: 'Thymosin beta-4, fragment (LKKTETQ), also known as TB-500.' List entry effective September 29, 2023; verified 2026-05-29. ↗
  7. U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee — agenda listing BPC-157, KPV, TB-500, and MOTs-C as bulk drug substances 'being considered for inclusion on the 503A Bulks List.' Verified 2026-05-29. ↗
  8. Jo JO, et al. Thymosin β4 induces the expression of vascular endothelial growth factor (VEGF) in a hypoxia-inducible factor (HIF)-1α-dependent manner. Biochim Biophys Acta. 2010;1803(11):1244-1251. ↗
  9. Morris DC, et al. A dose-response study of thymosin β4 for the treatment of acute stroke. J Neurol Sci. 2014;345(1-2):61-67. ↗
  10. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. ↗
  11. RegeneRx (sponsor). A Study of the Safety and Efficacy of Injectable Thymosin Beta 4 for Treating Acute Myocardial Infarction. ClinicalTrials.gov (2011) — trial withdrawn. ↗
  12. Sosne G, et al. Thymosin beta 4 promotes corneal wound healing and decreases inflammation in vivo following alkali injury. Exp Eye Res. 2002;74(2):293-299. ↗
  13. Kim S, Kwon J. Thymosin beta 4 improves dermal burn wound healing via downregulation of receptor for advanced glycation end products in db/db mice. Biochim Biophys Acta. 2014;1840(12):3452-3459. ↗
  14. Guarnera G, et al. Thymosin beta-4 and venous ulcers: clinical remarks on a European prospective, randomized study of safety, tolerability, and enhancement of healing. Ann N Y Acad Sci. 2007;1112:407-412. ↗
  15. El-Sayed N, et al. The combined impact of thymosin beta 4 and selenium on diabetic ulcers: a comparative study. Discover Biotechnology. 2025. ↗
  16. Kim TI, et al. Engineered Tandem Thymosin Peptide Promotes Corneal Wound Healing. Invest Ophthalmol Vis Sci. 2025;66(14):31. ↗
  17. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. ↗
  18. U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee — public calendar listing 'TB-500 (free base)' / 'TB-500 acetate' (with BPC-157, KPV, and MOTs-C) as substances 'being considered for inclusion on the 503A Bulks List.' An agenda for discussion, not a decision. Verified 2026-05-29. ↗
  19. U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act — definitions of Category 1 and Category 2, the bulks-list / nomination framework, and the role of the Pharmacy Compounding Advisory Committee. Verified 2026-05-29. ↗
  20. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks — entry 'Thymosin beta-4, fragment (LKKTETQ), also known as TB-500,' placed in Category 2 effective with the September 29, 2023 nominated-substances update, citing potential immunogenicity for certain routes and a lack of important safety information; the page current as of April 22, 2026 carries it as a withdrawn nomination. Verified 2026-05-29. ↗
  21. U.S. Food and Drug Administration, human drug compounding (Sections 503A and 503B): the lawful compounded-medication access pathway — licensed-prescriber evaluation (telehealth as a possible front-end channel), valid patient-specific prescription, 503A compounding pharmacy or 503B outsourcing facility, with bulk-substance eligibility limits (USP/NF monograph, component of an approved drug, or on the FDA bulks list). Verified 2026-05-29. ↗
  22. World Anti-Doping Agency. Prohibited List — TB-500 and thymosin beta-4 fall under prohibited peptide, growth-factor, and tissue-repair categories; banned in and out of competition for the relevant classes and detectable by LC-MS anti-doping assays. ↗
  23. RegeneRx (sponsor). A Study of the Safety and Efficacy of Injectable Thymosin Beta 4 for Treating Acute Myocardial Infarction. ClinicalTrials.gov. 2011. ↗
  24. Kleinman HK, Sosne G. Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide. Ann N Y Acad Sci. 2010. ↗
  25. Cha HJ, Jeong MJ, Kleinman HK. Role of thymosin beta4 in tumor metastasis and angiogenesis. J Natl Cancer Inst. 2003. ↗
  26. Zhang Y, et al. Thymosin beta 4 is overexpressed in human pancreatic cancer cells and stimulates proinflammatory cytokine secretion and JNK activation. Cancer Biol Ther. 2008. ↗
  27. Ho EN, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012. ↗
  28. Spurney CF, et al. Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouse. PLoS One. 2010. ↗
  29. Delcourt V, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. ↗