Tissue-repair peptide / β-thymosin family

TB-500

INN: Thymosin beta-4 (Tβ4 parent); TB-500 heptapeptide unnamed CAS: 77591-33-4 MW: ~4,921 Da (Tβ4) / ~887 Da (heptapeptide) Formula: C₂₁₂H₃₅₀N₅₆O₇₈S (Tβ4 parent)

Two-molecule calibration (used throughout)

The single most important fact for this monograph is that “TB-500” in community usage and “TB-500” in regulatory and clinical-trial usage refer, in most cases, to two structurally different peptides sold under the same name:

  • Full-length Tβ4 / Thymosin β4 / Tβ4 (43 aa). CAS 77591-33-4; MW ~4,921 Da. The endogenous G-actin sequestering peptide. Used in every regulated clinical programme (RGN-259, RGN-137, RGN-352, NL005). Carries both the actin-binding motif and the N-terminal Ac-SDKP tetrapeptide implicated in much of the proposed angiogenic / antifibrotic biology. [Academic secondary source — UniProt P62328]
  • TB-500 heptapeptide / Ac-LKKTETQ. MW ~887 Da. The synthetic N-terminally acetylated residue 17–23 fragment originally characterised in seized racehorse veterinary preparations. Named on the FDA 503A bulks list as “Thymosin Beta-4, Fragment (LKKTETQ).” Retains only the actin-binding motif; lacks Ac-SDKP. No published human PK, safety, or efficacy data of any kind. [Peer-reviewed preclinical study — Esposito et al. 2012, *Drug Test Anal*; Regulatory document — FDA 503A bulks list]

Vendor channels overwhelmingly treat the two as interchangeable; the regulatory and peer-reviewed record does not. The community-level result is that a buyer purchasing “TB-500” from Swiss Chems and a buyer purchasing “TB-500” from PeptideDeck may be receiving two structurally different molecules. Where this monograph uses “Tβ4” it means the 43-aa parent; “TB-500 heptapeptide” means Ac-LKKTETQ; “TB-500/Tβ4” is used only where regulators have explicitly grouped them (WADA S2.3, FDA 503A in some places).

1. Identity

Full-length Tβ4 (parent molecule).

  • Sequence (single-letter): SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES (43 aa) [Academic secondary source — UniProt P62328]
  • CAS 77591-33-4; molecular formula C₂₁₂H₃₅₀N₅₆O₇₈S; MW ≈ 4,921 Da [Academic secondary source — DrugBank DB05721 / UniProt P62328]
  • Class: G-actin sequestering β-thymosin; intracellular, ubiquitously expressed
  • INN: thymosin beta-4 (rINN). Sponsor/code names: timbetasin (USAN proposed for the topical ophthalmic formulation); RGN-259 (0.1 % topical ophthalmic solution); RGN-137 (dermal hydrogel); RGN-352 (IV); NL005 / gletimbetasin (recombinant Tβ4 IV, Beijing Northland) [Peer-reviewed human study — Sosne et al. 2022, PMC9820614; Academic secondary source — Patsnap Synapse drug record]

TB-500 heptapeptide (research-chemical molecule).

  • Structure: Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH (Ac-LKKTETQ); residues 17–23 of Tβ4 with N-terminal acetylation. MW ≈ 887.0 Da. No INN. [Peer-reviewed preclinical study — Esposito et al. 2012, *Drug Test Anal*]
  • FDA-recognised name on bulk-substance lists: “Thymosin Beta-4, Fragment (LKKTETQ)” [Regulatory document — FDA 503A bulks list, updates 2023-09-29 and 2026-04-15]

2. History and Development

  • 1981 — Goldstein, Low and colleagues isolate Tβ4 from calf thymus fraction TF5 and characterise its 43-aa primary structure; US patent 4,297,276 issued [Regulatory document — USPTO 4,297,276] 🔴 (Goldstein/Kleinman group)
  • 1991 — Tβ4 characterised as the principal intracellular G-actin sequestering peptide [Peer-reviewed preclinical study — Safer et al. 1991]
  • 1999–2002 — Tβ4 accelerates dermal and corneal wound healing in rodent models [Peer-reviewed preclinical — Malinda, Sosne, Kleinman et al.] 🔴
  • 2004 — Bock-Marquette / Srivastava publish in Nature that Tβ4 activates ILK–PINCH–Akt and improves cardiac function after coronary ligation in mice [Peer-reviewed preclinical — Bock-Marquette 2004 *Nature*, PMID 15565145] 🔴
  • 2007 — Smart / Riley Nature paper reports Tβ4-induced epicardial progenitor mobilisation and neovascularisation [PMID 17211460] (independent group)
  • 2008–2012 — Equine veterinary preparations of synthetic Ac-LKKTETQ (“TB-500”) emerge in standardbred and thoroughbred racing. Belgian writer Jempals’ explainer (“horses are injected with doses of only 10 mg… 1000 times more expensive than gold”) documents the crossover into the bodybuilding-forum register [Community source — Skynet/Jempals, c. 2011]. Bodybuilding forums (MESO-Rx, EliteFitness, AnabolicMinds) absorb the molecule directly from this equine pipeline.
  • 2009–2015 — RegeneRx Biopharmaceuticals builds a Tβ4 pipeline with codes RGN-259 (ophthalmic), RGN-137 (dermal), RGN-352 (IV cardiac). ReGenTree, LLC (US JV with GtreeBNT / HLB Therapeutics) licenses ophthalmic rights for the US/Canada in 2015 [Industry document — RegeneRx 10-K] ⚠️
  • 2012 — Ho et al. (Hong Kong Jockey Club) publish the canonical LC–MS detection method for Ac-LKKTETQ and metabolites in equine urine and plasma (LoD 0.01 ng/mL urine) — the analytical anchor for both equine sport and the regulatory characterisation of the research-chemical product [Peer-reviewed analytical study — Ho et al. 2012, PMID 23084823]
  • 2017–present — Beijing Northland Biotech develops recombinant 44-aa Tβ4 product NL005 (gletimbetasin) for acute myocardial infarction in China [Peer-reviewed human study — Wang et al. 2021, PMID 34346165] ⚠️
  • 2020 (Mar) — Fishman / Navarro / Servis racehorse-doping indictments (SDNY). 2020 (Oct) – 2021 (Feb) — Tailor Made Compounding (TMC) DOJ prosecution: pleaded guilty Oct 2020, forfeited $1,788,906.82, sentenced Feb 2021. TMC had been one of the largest 503A pharmacy channels for TB-500 to the optimization community pre-2020 [BloodHorse, 2020–2021; DOJ press release].
  • 2017–2022 — Second adoption wave driven by biohacker media; Ben Greenfield’s Boundless and “Wolverine Stack” framing becomes the canonical entry point for civilian users; Jay Campbell republishes; Vigorous Steve adds the DPP-4 inhibitor twist.
  • 2023 (Sep 29) — FDA places “Thymosin Beta-4, Fragment (LKKTETQ)” on the 503A Category 2 bulks list (significant safety risks) [Regulatory document — FDA 503A categories update 2023-09-29]
  • 2024–25 — SEER-3 European Phase 3 (RGN-259 in neurotrophic keratitis) fails primary endpoint per sponsor press release. No peer-reviewed primary publication identified as of 14 May 2026 [Press release — HLB Therapeutics / Korea Biomedical Review 2024–25] ⚠️
  • 2025 (Jun) — FDA raid on Amino Asylum (grey-market vendor).
  • 2026 (Mar) — Peptide Sciences voluntary shutdown [AMC Defense Law, 2026].
  • 2026 (Apr 15) — FDA republishes interim 503A list: LKKTETQ heptapeptide and 11 other peptides removed from Category 2 effective 2026-04-22 because the nominator withdrew. Substance scheduled for PCAC review 2026-07-23 (Docket FDA-2025-N-6895). Removal from Category 2 is procedural; the substance remains outside the affirmative 503A bulks list. [Regulatory document — FDA 503A list update 2026-04-15] [REFRESHED 2026-05-14]

3. Mechanism of Action

Demonstrated in humans (full-length Tβ4 only)

  • Ophthalmic surface repair. Corneal fluorescein staining and corneal sensitivity improvement in patients with neurotrophic keratopathy after 4-week topical 0.1 % Tβ4; demonstrated only in small, sponsor-conducted trials and not consistently reproduced in larger Phase 3 [Peer-reviewed human study — Sosne 2022 SEER-1, PMC9820614] ⚠️🔴
  • Tolerability after IV dosing of full-length recombinant Tβ4. No dose-limiting toxicity, no detectable anti-drug antibodies through 28 days at 0.05–25 µg/kg single and up to 5 µg/kg ×10 days [Peer-reviewed human study — Wang 2021, PMID 34346165] ⚠️
  • No demonstrated human pharmacology for the Ac-LKKTETQ heptapeptide. No human PK, safety, or efficacy study of the TB-500 heptapeptide has been published in indexed peer-reviewed journals.

Proposed / preclinical

  • G-actin sequestration. Tβ4 binds monomeric G-actin (Kd ≈ 0.4–2 µM) via the central actin-binding motif LKKTETQEK (residues 17–26); buffers the G/F-actin equilibrium and modulates cytoskeletal dynamics, cell motility, and wound-edge migration [Academic secondary source — UniProt P62328; GtoPdb thymosin β4 target page]
  • Ac-SDKP N-terminal tetrapeptide. Endogenous proteolytic cleavage of Tβ4 by prolyl oligopeptidase / meprin-α releases N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP), an antifibrotic and pro-angiogenic tetrapeptide. The TB-500 heptapeptide does not contain this region. [Peer-reviewed preclinical — Kumar et al., multiple]
  • ILK–PINCH–Akt activation in cardiomyocytes; anti-apoptotic and pro-survival signalling after ischaemic injury [Bock-Marquette 2004 *Nature*, PMID 15565145] 🔴
  • Epicardial progenitor mobilisation and neovascularisation in adult mouse heart [Smart 2007 *Nature*, PMID 17211460]
  • Anti-inflammatory. Reductions in NF-κB nuclear translocation, IL-1β, TNF-α, and MMP-mediated matrix degradation in corneal and dermal models [Peer-reviewed preclinical — Sosne et al., multiple] 🔴
  • Neuronal differentiation and remyelination. Improved neurological scores in rodent stroke and TBI models [Morris, Xiong et al.]

4. Regulatory Status

4.1 Drug-regulatory status

  • US FDA.
    • Marketing approvals: none for full-length Tβ4 or the LKKTETQ heptapeptide in any indication [Regulatory document — Drugs@FDA, accessed 2026-05-14]
    • Orphan drug designations: RGN-259 (Tβ4 ophthalmic) granted Orphan Designation for neurotrophic keratitis (2013); RGN-137 (Tβ4 dermal) granted Orphan Designation for epidermolysis bullosa [Regulatory document — FDA OOPD orphan database]
    • 503A bulks list (LKKTETQ heptapeptide):
      • 2023-09-29 — placed in Category 2 (significant safety risks)
      • 2026-04-15 — FDA republished the interim 503A list; “Thymosin Beta-4, Fragment (LKKTETQ)” (free base and acetate) is one of 12 peptides removed from Category 2 effective 2026-04-22 because the nominator withdrew the nomination. The substance is scheduled for Pharmacy Compounding Advisory Committee (PCAC) review on 2026-07-23 (Docket FDA-2025-N-6895) for possible inclusion on the 503A bulks list for wound healing. Removal from Category 2 is procedural and does not authorise compounding by itself; the substance remains outside the affirmative bulks list. [Regulatory document — FDA 503A list update 2026-04-15] [REFRESHED 2026-05-14]
    • Full-length Tβ4 itself does not appear on the affirmative 503A bulks list and is not listed by name in Category 2 (only the LKKTETQ fragment is).
  • EMA / MHRA: no marketing authorisation; no EU orphan designation identified [Regulatory document — EMA medicines database; MHRA Products database, 2026-05-14]
  • TGA (Australia): not registered on the ARTG; supply outside clinical trials requires SAS or Authorised Prescriber pathways [Regulatory document — TGA ARTG]
  • Health Canada: no Notice of Compliance; not listed in the Drug Product Database
  • PMDA (Japan): not approved
  • NMPA (China): NL005 (recombinant human Tβ4) in Phase II clinical development for acute MI; no marketing approval as of 2026-05-14 [Clinical trial registry — NCT05984134; CDE database] ⚠️
  • MFDS (Korea): no marketing approval; clinical trials sponsored by HLB Therapeutics ongoing/recently completed
  • GRLS (Russia): no registered product identified
  • WHO Essential Medicines List: not listed [WHO EML 23rd edition, 2025]

4.2 Anti-doping status

  • WADA 2026 Prohibited List — Section S2.3 Growth Factors and Growth Factor Modulators: “Thymosin-β4 and its derivatives e.g. TB-500” is explicitly named, alongside other repair-modulating growth factors [Anti-doping document — WADA 2026 Prohibited List, effective 2026-01-01, S2.3] [REFRESHED 2026-05-14]
  • In-competition / out-of-competition: Prohibited at all times. Substances in S2 are non-Specified Substances; the strict-liability sanction baseline under the World Anti-Doping Code is 4 years of ineligibility for a first violation absent No Significant Fault [WADC Art. 10.2; WADA 2026 List]
  • TUE eligibility: because neither full-length Tβ4 nor the LKKTETQ heptapeptide has marketing approval in any major jurisdiction for any indication, no therapeutic-use case meets the WADA TUE criterion of “established medical condition with a clearly necessary prohibited medication”; TUE approval is effectively unobtainable [WADA ISTUE 2026]
  • NCAA banned-drug-class status (2025–26): Class 6 “Peptide hormones, growth factors, related substances and mimetics”; Medical Exception Pre-Approval (MEPA) required and not practically obtainable in the absence of any recognised therapeutic indication [NCAA 2025-26 Banned Substances list]
  • DoD / OPSS (Operation Supplement Safety): thymosin β4 / TB-500 prohibited for service-member use as an unapproved drug; OPSS aligns with the WADA List [OPSS High Risk Supplement List; DoDI 6130.06]
  • Global DRO check date 2026-05-14: returns “Prohibited” status across UK/US/Canada/Japan sport jurisdictions
  • Equine sport: banned under racing-medication rules administered by ARCI, the Jockey Club, AQHA and parallel international authorities; Ho et al. 2012 LC–MS method is the canonical analytical reference for equine sport
  • Detection (human): Esposito et al. 2012 (Ghent) synthesised Ac-LKKTETQ and developed LC–MS/MS confirmation in human plasma and urine; multi-analyte LC–HRMS/MS methods (Thomas/Thevis 2012; Mazzarino 2015) and LC–FAIMS–MS/MS platforms (post-2023) bring routine LoDs for Ac-LKKTETQ and intact Tβ4 to ≤ 50 pg/mL in urine. Community-reported “30–45 day detection windows” are not anchored to any published WADA Technical Document.
  • Sanctions precedent.
    • 7 April 2025 — Canadian Centre for Ethics in Sport (now Sport Integrity Canada) announced a 4-year sanction for Emma Brooks, U SPORTS volleyball athlete (MacEwan University), for non-analytical use of BPC-157 and TB-500 between August–September 2024. Sanction runs to 3 December 2028 [CCES / Sport Integrity Canada media release, 2025-04-07]
    • 24 February 2025 — CCES 5-year sanction for powerlifter Mikal Thrones (multiple anabolic agents + admitted BPC-157 use; TB-500 not named)
    • Multiple equine ARCI-rule TB-500 positives in US Standardbred and Quarter Horse racing since 2014.

4.3 Last regulatory review

Last regulatory review: 2026-05-14

5. Formulations and Routes

  • Approved (any jurisdiction): none.
  • Clinical-stage formulations (full-length Tβ4).
    • RGN-259 — 0.1 % preservative-free topical ophthalmic solution (5 ×/day), full-length Tβ4 [NCT02600429 SEER-1; NCT05555589 SEER-2; SEER-3 EU] ⚠️
    • RGN-137 — Tβ4 dermal hydrogel (0.01–0.1 %), studied in epidermolysis bullosa [NCT00311766, terminated] ⚠️
    • RGN-352 — IV full-length Tβ4 for acute MI; Phase 2 NCT01311518 withdrawn (FDA cGMP clinical hold on API; trial never initiated) ⚠️
    • NL005 — IV recombinant 44-aa Tβ4 (0.05–25 µg/kg single, 0.5–5 µg/kg repeated; AMI dosing 0.5 or 1.0 µg/kg × 7 days post-PCI) [NCT04555824, NCT04555850, NCT05485818, NCT05984134] ⚠️
  • Pharmacokinetics (full-length Tβ4, IV, healthy Chinese volunteers). Dose-proportional Cmax and AUC across 0.05–25 µg/kg; no DLTs; no anti-drug antibody signal at 28 days [Wang 2021, PMID 34346165] ⚠️. Plasma t½ of intact Tβ4 ~1–2 h; endogenous baseline plasma Tβ4 ≈ 1 µg/mL complicates exogenous PK quantification.
  • Not supported by evidence. Oral and inhaled administration (no published human data). Subcutaneous self-injection of the Ac-LKKTETQ heptapeptide is the dominant route in research-chemical use but has no published human PK or efficacy data. Vendor-marketed oral capsule (Swiss Chems) and nasal spray formulations are mechanistically implausible for a peptide whose mucosal bioavailability is poor; Greenfield’s own podcast with Tremblay flagged the bioavailability problem.

6. Preclinical Evidence

  • In vitro. Tβ4 binds G-actin with Kd ≈ 0.4–2 µM; accelerates corneal and dermal epithelial cell migration; activates ILK and downstream Akt; suppresses NF-κB nuclear translocation [Safer 1991; Bock-Marquette 2004; Sosne et al., multiple] 🔴
  • Dermal wound healing. Tβ4 accelerates closure in rat full-thickness, diabetic db/db, and steroid-impaired wounds [Malinda, Kleinman et al.] 🔴
  • Corneal injury. Tβ4 accelerates epithelial closure in alkali-burn and debridement models [Sosne et al.] 🔴
  • Cardiac ischaemia. Bock-Marquette 2004 (Nature): Tβ4 reduced infarct size and improved fractional shortening in mouse coronary-ligation; ILK upregulation, Akt activation [PMID 15565145] 🔴. Smart 2007 (Nature): Tβ4 mobilised adult epicardial progenitors [PMID 17211460]. Porcine MI work showed Tβ4 enhanced engraftment of co-administered hiPSC-cardiomyocytes [Tan et al. 2021, PMC8315077]
  • Stroke / TBI. Improved neurological scores in rat embolic stroke and controlled-cortical-impact TBI models [Morris, Xiong et al.]
  • Toxicology. RegeneRx IND-enabling rat and dog toxicology supported topical, dermal and IV dosing without overt organ toxicity at multiples of clinical exposure; no carcinogenicity studies of full duration are publicly indexed [RegeneRx 10-K] ⚠️
  • Contradictory preclinical evidence (see §7.5 Dispute 1). Global and cardiac-specific Tmsb4x knockout mice are born at Mendelian ratios with normal heart development and adult cardiac function [Banerjee 2013, PMID 23371905]. Lineage-tracing studies do not support reprogramming of epicardial cells into cardiomyocytes by Tβ4 after MI [Zhou 2012, PMC3664360].
  • Translation note. Strong, multi-group preclinical signals in cornea, dermis, and heart have translated into only modest, sponsor-reported ophthalmic clinical signals; the most rigorous Phase 3 attempt (SEER-3, Europe) was negative on its primary endpoint. The TB-500 heptapeptide retains only the actin-binding motif and lacks the Ac-SDKP N-terminal region implicated in much of the proposed angiogenic and antifibrotic biology.

7. Clinical Evidence

Cochrane SR: none specific to thymosin β4, TB-500, or RGN-259 in any indication as of 2026-05-14. No PROSPERO-registered SR identified for tendon, ligament, muscle, sports-recovery or orthopaedic indications.

Phase 3 trials (full-length Tβ4 only — none for the heptapeptide).

Trial / NCTIndicationnSponsorResult
SEER-1 (NCT02600429)Neurotrophic keratopathy18ReGenTree ⚠️🔴Primary endpoint trend (p = 0.0656); 6/10 RGN-259 vs 1/8 placebo achieved complete corneal healing at 4 weeks [Sosne 2022, PMC9820614]
SEER-3 (EU, 25 sites)Neurotrophic keratitis78HLB Therapeutics / ReGenTree ⚠️Failed primary endpoint of complete corneal healing at 4 weeks; sponsor attributed result to “stronger-than-expected placebo effect.” Press release only; no peer-reviewed primary publication as of 2026-05-14 [HLB Therapeutics topline 2024–25] ⚠️
SEER-2 (NCT05555589)Neurotrophic keratopathy~70 (US)ReGenTree ⚠️Active/ongoing. No primary readout published.
ARISE-1/2/3 (DED)Dry eye317 + 600 + 700ReGenTree ⚠️Mixed; co-primary endpoints not consistently met; no NDA filed.
RGN-137 EB (NCT00311766)Epidermolysis bullosasmallRegeneRx ⚠️Terminated.
RGN-352 cardiac (NCT01311518)Acute MI, IV Tβ40RegeneRx ⚠️Withdrawn (FDA cGMP hold; trial never initiated).
NL005 Phase 1a/1bHealthy volunteers54 + 30Beijing Northland ⚠️Well tolerated; no SAEs; no anti-drug antibody signal.
NL005 Phase 2a (NCT05485818)Acute MI post-PCI60Beijing Northland ⚠️Completed; no peer-reviewed efficacy publication.
NL005 Phase 2b (NCT05984134)Acute MI post-PCI90Beijing Northland ⚠️Listed as COMPLETED on ClinicalTrials.gov; no peer-reviewed efficacy publication as of 2026-05-14

Randomised controlled trials of the TB-500 heptapeptide (Ac-LKKTETQ): none. No published RCT of any kind has been identified in PubMed, Embase, ICTRP or ClinicalTrials.gov.

Observational / uncontrolled human studies of the TB-500 heptapeptide: none indexed.

7.5 Disputed Claims

Dispute 1 — Bock-Marquette 2004 Nature cardiac protection vs subsequent translational failure.

  • Position A. The Bock-Marquette / Srivastava group reported Tβ4 reduced infarct size and improved cardiac function in mouse MI, with downstream confirmation in Smart 2007 (Nature) and Tan 2021 (porcine hiPSC-CM model) [PMIDs 15565145; 17211460; PMC8315077]
  • Position B. Banerjee / Kassem 2013 generated global and cardiac-specific Tβ4 knockout mice, found normal heart and vasculature, and concluded Tβ4 is dispensable for murine cardiac development and function [PMID 23371905]. Zhou 2012 reported that Tβ4 treatment after MI does not reprogram epicardial cells into cardiomyocytes by genetic lineage tracing [PMC3664360]. Clinically, RGN-352 never enrolled a patient and no Tβ4 cardiac programme has reported successful Phase 2 efficacy. Both sides remain published; no formal retraction issued.

Dispute 2 — Does the LKKTETQ heptapeptide retain the biology of full-length Tβ4?

  • Position A. The actin-binding motif L17–T23 is the most conserved sequence in the β-thymosin family, and Ac-LKKTETQ is sufficient for G-actin sequestration in vitro and for measurable bioactivity in equine wound and tendon models [Esposito 2012; Ho 2012]
  • Position B. The heptapeptide lacks the Ac-SDKP N-terminal tetrapeptide that drives much of the proposed angiogenic and antifibrotic activity of Tβ4; it also lacks the C-terminal segment implicated in nuclear actin shuttling and certain anti-inflammatory effects. No human PK, safety, or efficacy study of Ac-LKKTETQ has been published. Treating LKKTETQ and full-length Tβ4 as therapeutically equivalent is an unsupported assumption [Academic secondary source — UniProt P62328]

Dispute 3 — SEER-3 sponsor framing vs absence of peer-reviewed primary publication.

  • Position A. HLB Therapeutics characterises the SEER-3 result as a missed primary endpoint driven by a “stronger-than-expected placebo effect” and states it will continue with SEER-2 in the US [Press release 2024–25] ⚠️
  • Position B. The trial registration, protocol-specified primary endpoint of complete corneal healing at 4 weeks, and statistical analysis plan have not been re-released in a peer-reviewed primary publication. The negative outcome of a confirmatory Phase 3 in the only orphan-designated indication is, on the present record, a negative pivotal result; alternative explanations (placebo response, site heterogeneity, true lack of efficacy) cannot be adjudicated externally without the full dataset. Both characterisations exist in the public record; no peer-reviewed publication resolves them.

The three disputes above represent the substantive published scientific disagreement identified as of 2026-05-14.

7B. Community Evidence Layer

Driving subcommunity. Primarily bodybuilding / AAS-adjacent (MESO-Rx, AnabolicMinds, r/Steroids), secondarily sports-medicine / biohacker (Greenfield, Jay Campbell, peptide Substacks), with a smaller longevity-clinic channel. Pure-nootropic forums discuss TB-500 less than BPC-157.

Adoption lineage. Two waves. First wave (2008–2012): equine veterinary preparations directly absorbed by bodybuilding forums; the Hong Kong Jockey Club’s 2012 detection paper (Ho et al.) confirms the molecule under that name was the Ac-LKKTETQ heptapeptide. Second wave (2017–2022): biohacker mainstream pickup via Ben Greenfield’s Boundless and the “Wolverine Stack” framing. Greenfield’s pairing with BPC-157 is the canonical context fact — TB-500 is rarely discussed alone outside of the equine literature.

Current trajectory. Stable-to-slightly-down post-2023 FDA Category 2 reclassification and the 2025–2026 enforcement events (Amino Asylum raid Jun 2025, Peptide Sciences voluntary shutdown Mar 2026), but discussion has migrated to international channels rather than dissipated.

Community-documented protocols (sourced).

  • Canonical “loading + maintenance” template repeated across Greenfield, Jay Campbell, Swolverine, Hubmeded, peptidedosingprotocols.com, and MESO-Rx threads: 2.0–2.5 mg twice weekly × 4–6 weeks → 2.0–2.5 mg/week maintenance, SC. Goal: tendon / muscle / post-surgical recovery.
  • Greenfield “Wolverine” protocol: TB-500 2.0–2.5 mg + BPC-157 250 mcg AM + 250 mcg PM, with explicit endorsement of local injection “in or near any damaged muscle site” — mechanistically contested. ⚠️🔴
  • Greenfield longevity-page variant: TB-500 300–1000 mcg once daily, 3-month cycles. Lower-dose, diverges from the “loading” protocol.
  • Vigorous Steve “Bathmate” protocol: TB-500 + BPC-157 with 50 mg sitagliptin (Januvia, DPP-4 inhibitor) administered 1 hr pre-injection to “prevent breakdown.” ⚠️🔴 No corroborating community source; Steve-original.
  • peptides.org calculator: 2 mg/day × 15 days (aggressive variant extrapolated from equine literature). ⚠️
  • MESO-Rx Fr “Essai peptide TB-500” thread (2018+): OP describes “following the recommendations I read on the forum” — illustrates how the canonical protocol propagates without primary attribution.

Stack patterns.

  • Canonical “Wolverine Stack”: TB-500 + BPC-157. The dominant pairing across every biohacker, clinic, and grey-market vendor page. Pre-blended vials marketed under the “Wolverine Blend” name (Perfect B clinic, Doral FL, page dated 13 Mar 2026; Womenshealthofmd reproduces near-verbatim copy). Swiss Chems sells BPC-157 5mg + TB-500 5mg blend. ⚠️
  • “Wolverine+”: TB-500 + BPC-157 + ipamorelin/CJC-1295 + tesamorelin + GHK-Cu (Greenfield’s Boundless-derived expanded stack).
  • TB-500 + DPP-4 inhibitor (Vigorous Steve original).

Top claimed effects (sourced).

  • Tendon repair (Achilles, rotator cuff, lateral epicondylitis) — widespread
  • Ligament repair — widespread
  • Muscle tear / strain recovery — widespread
  • Reduced inflammation / “anti-inflammatory” — widespread
  • Joint pain / arthritis relief — common
  • Post-surgical recovery — common
  • Improved flexibility / “loosening up” — common
  • Skin / wound healing — common
  • Hair regrowth (scalp) — occasional but persistent; vendor-driven framing
  • Muscle growth — disputed within the community itself; peptides.org notes “no evidence linking it to muscle growth in human test subjects”

Reported side effects (sourced).

  • Lethargy / fatigue / “TB-500 lethargy” — the #1 community-known side effect, widespread across clinic safety pages and biohacker write-ups
  • Injection-site discomfort / redness — common
  • Head rush / lightheadedness shortly post-injection — common (Peptides Institute)
  • Mild headache — common
  • Theoretical pro-angiogenic / occult-tumour concern — frequently discussed; Vigorous Steve’s “Medical Screening” page is the loudest community voice on this, grouping TB-500/BPC-157/Cardarine as not directly causing tumours but capable of accelerating pre-existing cancer 🔴

Community dissent.

  • Fragment vs full-length. This is the live dispute the broader community has not internalised. Wikipedia, geneticlifehacks.com, peptidedosingprotocols.com, peptidedeck.com, deltapeptides.com explicitly identify TB-500 as the Ac-LKKTETQ heptapeptide. Most large grey-market vendors (Swiss Chems, Peptide Sciences, USPeptides, Particle Peptides) post product copy describing TB-500 as the full 43-aa Tβ4 — and several publish the full 43-aa sequence on their product page. Peptide Nerds splits the difference. No civilian community member’s third-party mass-spec confirming heptapeptide-vs-full-length identity was located in this pass.
  • Local vs systemic injection. Greenfield, Swolverine, Hubmeded endorse local “spot” injection near injury. PeptideDeck and Peptides Institute flatly contradict: “TB-500 is systemically active, so injection site does not need to be near the injury.” Unresolved.
  • Oral / nasal / transdermal TB-500. Swiss Chems sells oral capsule and nasal spray formats. Mechanistically implausible for a peptide this size; Greenfield’s own podcast guest (Tremblay) flagged the bioavailability problem yet the vendor formats remain on sale.

Vendor landscape (captured 2026):

  • Swiss Chems — 2 mg vial $34, 5 mg kit, 10 mg vial; 0.5-mg oral capsule × 60 $254.95; publishes the full 43-aa sequence in product copy
  • Peptide Sciences — voluntarily shut down Mar 2026; distinguished the two molecules on a comparison page while selling under the conflated SKU
  • USPeptides, Particle Peptides (EU), PeptideDeck, Delta Peptides — varying degrees of fragment-vs-full-length clarity
  • Tailor Made Compounding (historical, pre-DOJ action) — Oct 2020 plea, $1.79 M forfeiture; one of the largest 503A pharmacy channels for TB-500 pre-2020
  • Amino Asylum (historical) — FDA raid Jun 2025, site offline
  • “Wolverine Blend” (BPC-157 + TB-500) — pre-mixed 10/10 mg vials at $130–140 at Swiss Chems; clinic-supervised pricing markedly higher

Price range (USD, 2026): 2 mg vial $34–$45; 5 mg vial $30–$80; 10 mg vial $60–$130; pre-blended “Wolverine” 10/10 mg $130–$140; clinic-supervised premium.

COA practices. Swiss Chems publishes batch COAs but the COAs do not consistently specify which molecule (heptapeptide vs 43-mer) was tested. No civilian community third-party mass-spec confirming heptapeptide-vs-full-length identity surfaced in this pass.

Community Score: 80 / 100 (Usage 22/25; Codification 20/25; Effect consistency 15/25; Time-in-circulation 23/25). Sits in “established staple, codified by Greenfield/Wolverine lineage, but effect consistency pulled down by fragment-vs-full-length confusion and unresolved lethargy dose-response.”

Full community detail and 49-source bibliography are in the Pass 2 community-evidence file (project).

8. Safety Profile

Common AEs (from regulated Tβ4 trials — full-length only).

  • Topical ophthalmic (RGN-259): mild instillation discomfort, transient blurred vision; rates not higher than vehicle in pooled trials [Sosne 2022] ⚠️🔴
  • IV full-length Tβ4 (NL005): mild to moderate AEs, no DLTs through 25 µg/kg single dose and 5 µg/kg × 10 days; no SAEs; no anti-drug antibody signal at 28 days [Wang 2021] ⚠️
  • Dermal (RGN-137): limited reported data; injection-site / application-site reactions; no Phase 3-level safety dataset.

Serious adverse events. None attributable to study drug in completed Phase 1–3 trials of regulated formulations.

Community-reported AEs (TB-500 heptapeptide, grey-market self-administration).

  • Lethargy / fatigue — the dominant community-level complaint across clinic safety sections and biohacker write-ups. No published dose-response model; Real Peptides claims plateau at 2.5 mg implying higher loading doses are wasteful.
  • Head rush / lightheadedness shortly post-injection — common in community reports; no published mechanistic explanation.
  • Injection-site discomfort, mild headache, mild nausea — common.
  • None of these community-reported AEs have been characterised in any regulated trial of the heptapeptide, because no such trial exists.

Class concerns / theoretical risks.

  • Pro-angiogenic activity in any tissue raises a theoretical concern about occult malignancy and diabetic retinopathy progression; no signal detected in IND-enabling toxicology, but trial populations have excluded recent cancer history. Vigorous Steve’s community framing (“can accelerate the progression of pre-existing cancer & tumors tremendously”) overstates the strength of evidence but identifies the same theoretical concern that exists in any pro-angiogenic peptide.
  • Injection-site reactions and sterility / endotoxin risk are the dominant practical concerns for research-chemical Ac-LKKTETQ product, which is not manufactured to cGMP standards and is sold in vials labelled “not for human consumption.”
  • Identity / purity risk. Confiscated “TB-500” products have been characterised as Ac-LKKTETQ rather than full-length Tβ4 in independent analytical work; product-to-product variability and missequenced peptides have been documented in seized samples [Esposito 2012; Hartvig 2014]. The community’s own “fragment vs full-length” confusion is downstream of this.

Pharmacovigilance. No post-marketing pharmacovigilance dataset because no product is marketed. FDA MedWatch and EU EudraVigilance do not contain a Tβ4 / TB-500 product file.

Special populations. Pregnancy, lactation, paediatric, hepatic and renal impairment data are absent for both molecules.

Retractions / corrections. No retractions of primary Tβ4 / TB-500 / Bock-Marquette / Sosne / Goldstein papers identified in PubMed or Retraction Watch as of 2026-05-14. Bock-Marquette 2004 remains in print without a correction notice, though contradicted by later independent work (see §7.5 Dispute 1).

9. Drug Interactions

  • No formal drug–drug interaction studies have been published for full-length Tβ4 or the LKKTETQ heptapeptide.
  • Theoretical pharmacodynamic interactions.
    • With anti-angiogenic oncology agents (anti-VEGF mAbs, multi-kinase inhibitors): opposing effects on neovascularisation; no clinical data.
    • With systemic corticosteroids and immunosuppressants: possible attenuation of Tβ4’s anti-inflammatory effects; no clinical data.
    • With anti-fibrotic agents (pirfenidone, nintedanib): theoretical overlap via Ac-SDKP-mediated antifibrotic signalling of full-length Tβ4; not relevant to the heptapeptide, which lacks Ac-SDKP.
  • Community-original “DPP-4 inhibitor pre-injection” protocol (Vigorous Steve). Co-administration of 50 mg sitagliptin 1 h before TB-500/BPC-157 is claimed to “prevent breakdown.” DPP-4 cleaves N-terminal Xaa-Pro and Xaa-Ala dipeptides; Ac-LKKTETQ has neither configuration at the N-terminus, and the rationale is mechanistically weak. No corroborating community or published source.
  • No reported CYP-mediated metabolism; clearance is proteolytic.

10. Research Gaps

  1. No Phase 3 success in any indication in >25 years of clinical development; the most advanced indication (neurotrophic keratitis, RGN-259) failed its European pivotal trial (SEER-3) and a US confirmatory trial (SEER-2) has not reported a positive primary endpoint as of 2026-05-14.
  2. Cardiac translation is effectively absent in humans. RGN-352 withdrawn before enrolment; NL005 Phase 2b completed without peer-reviewed efficacy publication.
  3. Dermal / epidermolysis bullosa programme terminated at Phase 2.
  4. The TB-500 heptapeptide has zero published human RCT data of any kind — no PK, no safety, no efficacy.
  5. Orthopaedic, tendon, ligament, muscle and sports-recovery indications — the actual community use case — have no supporting human RCT, observational cohort, or registry data. Animal models in tendon and muscle exist but are not pivotal, and the animal work overwhelmingly uses full-length Tβ4 rather than the heptapeptide sold to users.
  6. No Cochrane systematic review of Tβ4 / TB-500 in any indication.
  7. No head-to-head trials against BPC-157, GHK-Cu, polydeoxyribonucleotide (PDA), platelet-rich plasma, or any approved tissue-repair modality.
  8. Global Tβ4 knockout phenotype (Banerjee 2013) is not yet reconciled with the rescue-phenotype narrative of the Bock-Marquette / Smart preclinical literature.
  9. No published third-party mass-spec study characterising the identity of marketed “TB-500” vials across vendors and batches.
  10. Lethargy as community-dominant AE — no dose-response characterisation, no mechanistic explanation, no published clinical confirmation.

11. Bottom-Line Encyclopedia Note

Thymosin β4 has been in clinical development for over 25 years without a single marketing approval anywhere in the world. The best-supported indication — neurotrophic keratitis with topical full-length Tβ4 (RGN-259) — failed its European Phase 3 (SEER-3) primary endpoint in 2024–25 per sponsor press release; no peer-reviewed primary publication has appeared, and a parallel US Phase 3 (SEER-2) remains unreported. The cardiac IV programme (RGN-352) was never initiated; the China cardiac programme (NL005) has completed Phase 2b without peer-reviewed efficacy results. The Ac-LKKTETQ heptapeptide sold as “TB-500” is structurally not the molecule used in any of these clinical trials, and has no published human pharmacokinetic, safety, or efficacy data. The WADA 2026 Prohibited List explicitly prohibits “Thymosin-β4 and its derivatives e.g. TB-500” at all times; a 4-year sanction was issued in Canada in April 2025 for non-analytical TB-500 + BPC-157 use. FDA placed the LKKTETQ heptapeptide in 503A Category 2 in September 2023; on 22 April 2026 it was removed because the nominator withdrew, scheduled for PCAC review 23 July 2026 — removal from Category 2 does not authorise compounding.

11B. Gap Analysis — Where Science and Community Diverge

The Gap Analysis names where the two layers agree, disagree, and where one knows something the other doesn’t. TB-500 is the cleanest example in this encyclopedia of the “high community + low science, untested-not-tested-negative” pattern. A 25-year clinical programme exists, but it tests a different molecule (full-length Tβ4) in different indications (cornea, dermis, heart) than the molecule the community uses (Ac-LKKTETQ heptapeptide) for the indications the community cares about (tendon, ligament, muscle recovery). The science layer is not negative on the community use case — it is silent on it.

TopicScience LayerCommunity LayerGap
Tendon / ligament / muscle recovery — the actual community use caseZero human trials of any kind. Animal data exists in tendon and muscle, but uses full-length Tβ4 not the heptapeptide.Codified loading + maintenance protocol across Greenfield, Swolverine, MESO-Rx, clinic pages. Widespread positive self-report.🔴 Untested. Community is using a molecule (Ac-LKKTETQ) with no published human data for an indication (tendon/ligament) with no human RCT in either molecule. The community is not wrong about the absence of negative data; they are wrong about the presence of positive data.
What molecule is in the vialRegulatory (FDA 503A) and analytical chemistry literature are unambiguous: “TB-500” refers to Ac-LKKTETQ.Vendor-level conflation. Swiss Chems, Peptide Sciences, USPeptides publish full 43-aa Tβ4 sequence under the “TB-500” SKU. PeptideDeck, Wikipedia, Genetic Lifehacks call out the heptapeptide. No community consensus, no civilian third-party MS verification surfaced.🔴 MAJOR GAP — the community is buying two structurally different peptides under one name and reporting effects on both as if they were one substance. This contaminates every effect claim downstream.
WADA banned statusExplicitly named in WADA 2026 S2.3 (“Thymosin-β4 and its derivatives e.g. TB-500”), prohibited at all times; sanction precedent (Emma Brooks, 4 years, April 2025).Discussed (Optmzd, peptide blog roundups); not central to most clinic / biohacker framing.Community-aware but underweighted. Anyone subject to drug testing — NCAA, military, USADA, equine — needs to know this before the first dose, not after.
Pro-angiogenic / occult tumour riskTheoretical class concern in any pro-angiogenic peptide; no signal in regulated trials, which excluded recent cancer history.Discussed prominently by Vigorous Steve (“can accelerate the progression of pre-existing cancer & tumors tremendously”); omitted from clinic marketing pages.Aligned in direction; community split on magnitude. Steve’s framing overstates the evidence; clinic pages omit the concern entirely. The defensible synthesis sits between them.
Lethargy as #1 community AENot characterised in any regulated trial.Universally reported across clinic safety pages, biohacker write-ups, forum threads. Real Peptides claims a dose plateau at 2.5 mg.Community-only signal that science cannot address. No regulated trial of the heptapeptide exists to confirm or refute it.
Local vs systemic injectionPharmacokinetics support systemic distribution of the heptapeptide (small peptide, rapid distribution); no published clinical study of local injection.Greenfield, Swolverine, Hubmeded endorse local “spot” injection. PeptideDeck and Peptides Institute flatly contradict.Community internally split, science silent. The “spot injection” lore persists despite no mechanistic support.
Hair regrowth, neuroprotection, cardiac repair, longevity claimsEach indication has full-length Tβ4 preclinical or early-clinical signal in regulated programmes that have not translated to a Phase 3 win.Reproduced as confident vendor-page claims; bundled into “general systemic healing” framing.Community extrapolates from full-length Tβ4 preclinical and orphan-indication signals onto heptapeptide use in unrelated populations. Bridge of inference is two molecules wide.
Bock-Marquette cardiac translationDisputed in the peer-reviewed literature; Tβ4 KO mice are normal (Banerjee 2013); RGN-352 never enrolled a patient.Treated as established mechanism; reproduced across vendor pages.Community treats a contested preclinical claim as settled, while the relevant clinical programme has failed to launch.
SEER-3 negative readoutPress-release only; no peer-reviewed primary publication; sponsor frames as placebo-driven.Largely unmentioned in optimization-community discourse.Both layers blind to the most important recent data point — the most advanced TB-500/Tβ4 clinical trial failed and there is no peer-reviewed publication to adjudicate the result.
DPP-4 inhibitor “pre-injection” protocolNo published evidence; mechanistically weak (Ac-LKKTETQ has no Xaa-Pro/Xaa-Ala N-terminus)Promoted by Vigorous Steve as a Steve-original protocol element.Community-original protocol with no published support. Adds an additional drug exposure to a community use case with no published safety data on the index drug.

Net characterisation. TB-500 sits in the High community + Low science, “untested” subclass of the gap pattern matrix. This is the cleanest example in the encyclopedia of community-evidence-without-clinical-evidence. The two highest-consequence gaps are:

  1. The molecule the community uses (Ac-LKKTETQ) has zero published human trial data of any kind for the indications the community cares about. The 25-year clinical programme is in different indications, with a different molecule, with no Phase 3 success and a recent confirmatory negative readout.
  2. Vendor-level conflation of heptapeptide and full-length Tβ4 means the community is, at the SKU level, reporting effects on two different peptides as if they were one substance. No civilian third-party mass-spec verification was located in this pass.

This is not a “community ahead of science” pattern. It is a “community confident in the absence of relevant evidence” pattern, sustained by transferred inference from full-length Tβ4 preclinical work to heptapeptide self-injection.

12. Three Paths

You choose your risk tolerance. This monograph provides the data, not the recommendation.

Conservative path — wait. Defined as not engaging until at least one of (a) peer-reviewed publication of a Phase 2 or Phase 3 human trial of the TB-500 heptapeptide (Ac-LKKTETQ) in any indication, (b) marketing authorisation for full-length Tβ4 or the heptapeptide in any major jurisdiction, (c) peer-reviewed publication of a positive Phase 3 in any indication of full-length Tβ4, or (d) FDA 503A bulks-list inclusion after the 23 July 2026 PCAC review (the regulatory floor for legitimate compounding access). None of these gates is met as of 15 May 2026; the most recent Phase 3 (SEER-3) was negative. TB-500 does not meet the conservative bar in any of its forms.

Moderate path — Tier C/D with supervision (full-length Tβ4 only). Defined as engaging with full-length Tβ4 (not the heptapeptide) through (a) a clinical trial — NL005 Phase 2 trials at Beijing Northland sites in China, or any reopened RGN-259 enrolment, or (b) a 503A compounding pharmacy explicitly sourcing the 43-aa sequence with a HPLC/MS certificate of analysis confirming identity, under licensed-clinician oversight. The heptapeptide pathway does not have a moderate option — no clinical-trial access, no 503A bulks-list status, no marketing authorisation, no published human safety data. Subject to drug testing? The moderate path collapses into the conservative path: WADA explicitly names both molecules.

High-tolerance path — grey-market with mitigation (acknowledging which molecule). Defined as acknowledging that (a) none of the four conservative gates is met, (b) WADA bans both molecules at all times with a 4-year first-violation sanction baseline, (c) what arrives in the vial may not be the molecule the label names, and (d) the community use case has no human evidence. The community mitigation stack documented in Pass 2: third-party mass-spec verification (HPLC at minimum, not just COA from vendor) to confirm whether the product is heptapeptide or full-length, with a community-cost-pool model; awareness that lethargy is the dominant AE and may be dose-responsive; dose at the lower end of the community range (≤2 mg per administration); cap weekly exposure below the loading-protocol headline; structured bloodwork including a baseline cancer-screening panel given the pro-angiogenic theoretical concern; sterile-injection technique; physician-monitoring dialogue even where the physician has not prescribed; drug-testing exposure assessed honestly — collegiate / military / equine athletes are exposed even with non-analytical-positive sanction risk (Emma Brooks 2025).

13. Key References

Scientific:

Peer-reviewed human studies

  • Sosne G et al. 0.1 % RGN-259 (Thymosin β4) ophthalmic solution for neurotrophic keratopathy: SEER-1 Phase 3. Int J Mol Sci 2022, PMC9820614 ⚠️🔴
  • Wang X et al. First-in-human Phase 1 study of recombinant human thymosin β4 (NL005) IV. J Cell Mol Med 2021;25:8222–8228. PMID 34346165 ⚠️
  • HLB Therapeutics SEER-3 (EU NK Phase 3) topline 2024–25 [Press release — not peer-reviewed] ⚠️

Peer-reviewed preclinical / mechanistic studies

  • Bock-Marquette I et al. Thymosin β4 activates ILK and promotes cardiac cell migration, survival and repair. Nature 2004;432:466–472. PMID 15565145 🔴
  • Smart N et al. Thymosin β4 induces adult epicardial progenitor mobilization and neovascularization. Nature 2007;445:177–182. PMID 17211460
  • Banerjee I et al. Thymosin β4 is dispensable for murine cardiac development and function. Circ Res 2013, PMID 23371905 [contradicts Dispute 1 Position A]
  • Zhou B et al. Thymosin β4 treatment after MI does not reprogram epicardial cells into cardiomyocytes. J Mol Cell Cardiol 2012, PMC3664360 [contradicts Dispute 1 Position A]
  • Tan SH et al. Tβ4 increases reparative potency of hiPSC-CMs in porcine AMI. Theranostics 2021, PMC8315077

Peer-reviewed analytical / anti-doping

  • Esposito S et al. Synthesis and characterization of the N-terminal acetylated 17–23 fragment of thymosin β4 identified in TB-500. Drug Test Anal 2012
  • Ho ENM et al. Doping-control analysis of TB-500 in equine urine and plasma by LC–MS. J Chromatogr A 2012, PMID 23084823

Clinical trial registry entries (selected)

  • NCT02600429 SEER-1 (NK); NCT05555589 SEER-2 (NK, ongoing); SEER-3 (EU NK Phase 3, IOBA-registered)
  • NCT01393132 ARISE-1; NCT02469259 ARISE-2; NCT03937882 ARISE-3 (DED)
  • NCT00311766 RGN-137 EB (terminated); NCT01311518 RGN-352 cardiac (withdrawn)
  • NCT04555824, NCT04555850 NL005 Phase 1; NCT05485818 NL005 Phase 2a AMI; NCT05984134 NL005 Phase 2b AMI

Regulatory documents

  • FDA 503A Categories Update 2023-09-29 (LKKTETQ placed in Category 2)
  • FDA 503A bulks list republication 2026-04-15; Federal Register PCAC scheduling 2026-07-23 (Docket FDA-2025-N-6895)
  • WADA 2026 Prohibited List, S2.3 Growth Factors and Growth Factor Modulators (effective 2026-01-01)
  • NCAA 2025-26 Banned Substances list, class 6
  • CCES / Sport Integrity Canada media releases 2025-02-24 (Thrones), 2025-04-07 (Brooks)

Academic secondary sources

  • UniProt P62328 (TMSB4X, human thymosin β4)
  • GtoPdb (IUPHAR/BPS Guide to Pharmacology), thymosin β4 target page
  • DrugBank DB05721

Community:

  • Wikipedia “TB-500” — explicit Ac-LKKTETQ identification
  • Genetic Lifehacks “Thymosin Beta 4: Genetics & Supplemental Peptides” — clarifies fragment vs full-length
  • peptidedosingprotocols.com “TB-500 Dosage Guide” (Garret Grant, May 2026) — flags fragment/full-length issue ⚠️
  • Peptide Nerds “TB-500 vs Thymosin Beta-4” — splits the difference ⚠️
  • Ben Greenfield Life “Wolverine Peptide Stack” / Boundless — canonical biohacker entry point ⚠️🔴
  • Jay Campbell “Wolverine Healing Stack” — Greenfield republication ⚠️🔴
  • Vigorous Steve — “Bathmate Experiment”, “Medical Screening”, PEPTIDES RANKED podcast ⚠️🔴
  • Swolverine “TB-500 Dosage Guide”, Hubmed “TB 500 Peptide”, peptides.org calculator ⚠️
  • Swiss Chems, Peptide Sciences, USPeptides, Particle Peptides, Delta Peptides, PeptideDeck product pages ⚠️
  • Perfect B (Doral FL clinic) “Wolverine Peptide Stack” (page dated 13 Mar 2026); Womenshealthofmd “Wolverine Blend” (near-verbatim copy) ⚠️🔴
  • MESO-Rx Français “Essai peptide TB-500” thread (2018+); legacy “tb 500 (thymosin beta 4)” archive
  • Skynet/Jempals 2011 TB-500 explainer — racehorse-veterinary lineage source
  • BloodHorse “Compounding Pharmacy Admits Guilt” (TMC); “Meadowlands to Exclude…” (TB-7 customer list)
  • PeptideExaminer “FDA’s Peptide Crackdown: A Complete Timeline”; “FDA’s War on Peptides: 2024-2026 Enforcement Timeline”
  • AMC Defense Law “The Peptide Industry Is Under the Microscope” (2026)

Gap acknowledged in Pass 2. Direct Reddit thread-level evidence (r/Peptides, r/PeptideUmbrella, r/Steroids permalinks with thread title/date) was not retrievable through Pass 2’s search tooling and should be a Pass-2 revisit target with archive.org / Pushshift-style tooling. The Derek/MPMD podcast corpus on TB-500 could not be confirmed by direct citation; community references to him discussing the peptide exist but specific episode IDs were not retrieved.

14. Audit / Refresh Trail

  • Composed: 15 May 2026
  • Science-layer source: tb-500_sci_2026-05-14_E3.md (Pass 1; last refreshed 14 May 2026; prior content drawn from §3 of Thymic_and_Immune_Peptides__Regulatory_and_Clinical_Evidence_Review.md, last reviewed 9 May 2026)
  • Community-layer source: tb-500_com_2026-05-15_C80.md (Pass 2; compiled 15 May 2026)
  • Section 4 Last regulatory review: 2026-05-14
  • Next refresh triggers:
    • PCAC outcome 2026-07-23 — possible 503A bulks-list inclusion of LKKTETQ heptapeptide for wound healing; would materially change the moderate path
    • SEER-3 peer-reviewed primary publication, if and when it appears
    • SEER-2 top-line and/or primary publication
    • NL005 Phase 2b peer-reviewed efficacy publication (Beijing Northland)
    • Any WADA list change (annual cycle, effective each 1 Jan)
    • Any new CCES / USADA / Sport Integrity Canada sanction with TB-500 / Tβ4 as a named substance
    • Any published third-party mass-spec study characterising “TB-500” vials by molecule
    • Any peer-reviewed Phase 1 of the TB-500 heptapeptide (the single largest evidence-base shift possible for this entry)
    • Direct Reddit / Pushshift retrieval of the community corpus that Pass 2 could not access
    • Resolution of Dispute 1 (Tβ4 cardiac biology) by a published independent rescue study or a retraction of foundational papers
    • Material shift in the grey-market vendor landscape (further FDA enforcement actions, vendor scandals, COA failures)