{"slug":"tb-500-fragment-17-23","seoKey":"tb500fragment1723","inn":"Fequesetide","displayName":"TB-500 Fragment (17-23)","codes":["LKKTETQ","Tβ4 (17-23)"],"synonyms":["fequesetide","fequesetidum","féquésétide","fequesetida","Leu-Lys-Lys-Thr-Glu-Thr-Gln","TB4 Frag 17-23","actin-binding domain of thymosin beta-4"],"legalClass":"research_chemical","identifiers":{"cas":"476014-70-7","pubchemCid":10169788,"inchikey":"LVLWJWXFRFTMLK-JMWNXRNDSA-N","formula":"C36H66N10O13","molecularWeight":847,"sequence":"LKKTETQ"},"approvals":[{"market":"US","status":"not_approved","note":"Not approved: no approved product, no labelling and no monograph. openFDA searches for fequesetide, LKKTETQ and TB-500 returned no match on 2026-09-23, while control searches returned results. The agency's briefing document of 2026-05-15 proposed not adding TB-500 free base or acetate to the list of bulk substances pharmacies may compound with, citing no human data, no toxicology and naming so inconsistent that it is a safety risk. Its advisory committee voted 8 to 6 with one abstention the other way on 2026-07-23; the counts come from secondary reports, no official minutes were available on 2026-09-23, and the vote has no legal effect. Both concern the capped TB-500, not expressly this uncapped fragment. The compounding safety-risk list names an entry 'Thymosin beta-4, fragment (LKKTETQ), also known as TB-500' under substances nominated but withdrawn.","source":"https://www.fda.gov/media/193349/download"},{"market":"EU","status":"not_approved","note":"Not approved: no centralised authorisation and no assessment report. The agency's dataset of public assessment reports held no entry for fequesetide, thymosin, TB-500, LKKTETQ or timbetasin on 2026-09-23, while the control search found semaglutide. The substance is not in the European Pharmacopoeia.","source":"https://www.ema.europa.eu/en/medicines"},{"market":"DE","status":"not_approved","note":"Not approved: neither a national nor an EU authorisation exists. The annex to the anti-doping act lists 'Thymosin-beta-4 und seine Derivate', with TB-500 only as an example, and its closing sentence includes derivatives; the fragment is not named. The quantity regulation sets the non-small amount at 100 mg. Whether the uncapped fragment counts as a derivative in a given case is a legal question not decided here.","source":"https://www.gesetze-im-internet.de/antidopg/anlage.html"},{"market":"UK","status":"not_approved","note":"Not approved: the electronic medicines compendium returned no result for fequesetide, thymosin or TB-500 on 2026-09-23, while the control search returned entries. Classification under the Misuse of Drugs Act was not checked against a primary source.","source":"https://www.medicines.org.uk/emc/search?q=fequesetide"},{"market":"AU","status":"scheduled","date":"2026-05-28","note":"The Poisons Standard of June 2026 lists 'TB-500' and 'THYMOSIN BETA 4' as two separate Schedule 4 entries, both also in Appendix D clause 5 as items 35 and 36, so possession without authority is illegal. The uncapped fragment is not named. The instrument covers derivatives of listed substances unless they are listed elsewhere, so the fragment would most likely be included; this is a reading of the legal text, not a decision by the regulator. No registered product exists.","source":"https://www.legislation.gov.au/F2026L00633/asmade"},{"market":"CA","status":"not_approved","note":"Not approved: the active-ingredient query of the drug product database returned 0 records for fequesetide, thymosin and TB-500 on 2026-09-23, while the control query for semaglutide returned 51, so the negative finding is sound.","source":"https://health-products.canada.ca/api/drug/activeingredient/?ingredientname=fequesetide"},{"market":"CH","status":"not_approved","note":"Not approved: the regulator's extended list of authorised human medicines held no entry for fequesetid, thymosin, TB-500, LKKTETQ or timbetasin on 2026-09-23, while the control search found 17 entries for semaglutid. A 2026 joint enforcement action on peptide consignments does not name this substance.","source":"https://www.swissmedic.ch/swissmedic/en/home/services/listen_neu.html"}],"devStage":"preclinical","strongestEvidence":"animal","wada":{"status":"prohibited","section":"S2.3","listYear":2026,"source":"https://www.wada-ama.org/en/prohibited-list"},"trials":[],"sameAs":["https://pubchem.ncbi.nlm.nih.gov/compound/10169788"],"lastVerified":"2026-09-30","version":"1.1","published":true,"locale":"en","title":"TB-500 Fragment (17-23): what the studies show, status and safety","summary":"The fragment LKKTETQ / fequesetide has seven amino acids and lacks the N-terminal acetyl group of Ac-LKKTETQ. It also differs from full-length TB-4, which has 43 amino acids. Aged-mouse wound results concern unacetylated LKKTETQ; a separate cell assay found no significant effect of Ac-LKKTETQ under its tested conditions. Different molecules and models do not establish clinical superiority of either fragment.","updated":"2026-09-30","url":"https://mypep.app/peptides/tb-500-fragment-17-23"}