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Meds TB-500

A precise, evidence-first readout of the TB-500 (Ac-LKKTETQ) and thymosin beta-4 research literature - what the studies establish, where the human data stop, and how compounded access actually stands.

The numbered marks identify the study or government page

TB-500 references connect the findings with their published sources.

The researchers’ interest began with copying a part that holds a protein used for cell movement. Most papers then examined the longer thymosin beta-4, which matters as you weigh claims about treatment with the copied part.

Revisit the findings about healingRead the answers about treatment

Each numbered mark leads to a named paper or government page below

The numbers beside findings match the papers and government pages listed below. You can follow the links to see what researchers tested and found.

The TB-500 pharmacy-use explanation relies on FDA's pages for the permission question. Entries 16-18 identify those government sources, so you can check an access claim.

Most healing papers gave thymosin beta-4 rather than the copied part. Before judging a claim for your care, check which substance the researchers gave.

The human safety paper tested another substance while animal studies gave mixed results

The Phase 1 human study was an early test looking mainly for unwanted effects. Volunteers received thymosin beta-4 through a vein rather than the copied chain [6].

Chance assigned volunteers to protein treatment or a placebo, a similar treatment without the protein. A placebo supplies a comparison treatment, but this study didn't test TB-500.

The 2026 Sports Medicine review described encouraging animal repair findings and scarce human safety evidence [15]. The shorter chain was among the unapproved substances discussed, with limited checks on use.

Cancer studies raised concern about thymosin beta-4 and the spread of cancer [7][8]. Some researchers used dishes of pancreatic cancer cells; the study didn’t treat people with cancer.

Treatment with the longer protein increased muscle fibers in mice, without increasing strength [9]. A pig test likewise found no protection against heart damage from stopping and restarting blood flow [14].

Skin, heart, brain, and vessel papers mostly report on animals or laboratory cells [2][3][4][10][11][12][13]. Those findings can't establish useful healing from the copied substance for you.

Researchers also attached another protein part to thymosin beta-4 to examine its hold on actin [1]. Actin is a protein used for cell movement; the X-ray examined prepared proteins, without injured patients.

The protein X-ray showed details 2 angstroms apart, a very small distance. In the 1:1 pairing, actin was held by the longer protein, with one of each.

Covering actin's ends kept spare pieces from joining the strands cells use to move [5]. A reserve of spare pieces supports movement, without proving that the copied chain heals your injury [5].

You need useful human recovery and safety to judge a treatment for yourself. These papers explain the repair hopes and failures without establishing that treatment benefit.

  1. Irobi E, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. ↗
  2. 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. ↗
  3. Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. ↗
  4. 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. ↗
  5. 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. ↗
  6. 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. ↗
  7. Cha HJ, Jeong MJ, Kleinman HK. Role of thymosin beta4 in tumor metastasis and angiogenesis. J Natl Cancer Inst. 2003;95(22):1674-1680. ↗
  8. 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;7(3):419-423. ↗
  9. 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;5(1):e8976. ↗
  10. 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. ↗
  11. Qiu P, et al. Thymosin beta4 promotes matrix metalloproteinase expression during wound repair. J Cell Physiol. 2006;208(1):165-173. ↗
  12. Sosne G, et al. Thymosin beta 4 suppression of corneal NFkappaB: a potential anti-inflammatory pathway. Exp Eye Res. 2007;84(4):663-669. ↗
  13. Stark C, et al. Cardioprotection by systemic dosing of thymosin beta four following ischemic myocardial injury. Front Pharmacol. 2013;4:149. ↗
  14. Stark C, et al. Systemic Dosing of Thymosin Beta 4 before and after Ischemia Does Not Attenuate Global Myocardial Ischemia-Reperfusion Injury in Pigs. Front Pharmacol. 2016;7:115. ↗
  15. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. ↗
  16. 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'; Category 2, effective with the September 29, 2023 nominated-substances update). ↗
  17. U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act (Category 1 and Category 2 definitions; 503A/503B framework; bulks-list nomination and PCAC evaluation process). ↗
  18. U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee (published agenda listing 'TB-500 (free base)' / 'TB-500 acetate', BPC-157, KPV, and MOTs-C as substances being considered for inclusion on the 503A Bulks List — an advisory discussion, not a decision). ↗
  19. 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. ↗
  20. Delcourt V, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. ↗