Like KLOW, the Wolverine stack is a mixture rather than a molecule — in this case just two, at equal weights. The name comes from a comic-book character who heals quickly. It carries no technical meaning and appears in no pharmacopoeia.
What makes it worth its own entry is that neither ingredient is quite what its name suggests, and that the small body of registered human evidence behind both of them has a shape worth looking at directly.
The two molecules
| BPC-157 | TB-500 | |
|---|---|---|
| Residues | 15 | 7 |
| Sequence | GEPPPGKPADDAGLV | LKKTETQ (N-acetylated) |
| Molecular weight | 1,419.5 | 889.0 |
| PubChem CID | 9941957 | 62707662 |
| Named after | A compound isolated from gastric juice | Thymosin beta-4 — of which it is a fragment |
Sold at 10 mg each, the vial holds about 7.04 micromoles of BPC-157 and 11.25 of TB-500: equal weights are not equal molecule counts, because the larger peptide gives fewer of them per milligram.
TB-500 is a fragment, and the registry says which one
Thymosin beta-4 is a 43-residue protein with a literature of its own — 1,054 PubMed records on 2026-09-18, against 27 for "TB-500". Those are not the same evidence base, and the difference is the single most common error made about this stack.
The one registered study of TB-500 is unusually helpful here, because it names the molecule in its own title: "TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD" (NCT07487363). That pins the fragment to residues 17 through 23 of the parent protein, which is more precision than most sellers offer.
Note also what the study is for: cardiovascular biomarkers. Not tendon, not ligament, not muscle — the uses the stack is sold for. That matches what this library found when it counted the parent protein's trials: none of thymosin beta-4's registered studies names a tendon, ligament or muscle either.
The arithmetic that reveals the acetyl group
The seven letters of LKKTETQ do not account for the molecule's mass, and the way they fail is informative.
Free amino acids L+K+K+T+E+T+Q = 955.07
Six peptide bonds, six waters lost − 108.09 (6 × 18.015)
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Calculated = 846.98
PubChem CID 62707662 = 889.00
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Unexplained = +42.02
42.02 is the mass of an acetyl group. TB-500 is acetylated at the N-terminus, and the sequence notation does not show it. The same arithmetic performed on BPC-157 lands within 0.04 of its published mass, and on KPV within 0.01 — so the gap here is a real modification, not rounding. The method is set out in this library's entry on the peptide bond.
Nothing has been tested as a pair
A ClinicalTrials.gov search for the two compounds in combination returned zero records on 2026-09-18.
Every claim made for the stack as a stack — that the two are complementary, that one works locally while the other works systemically — is an inference from the ingredients rather than a finding about the mixture. That is not unusual for blends, and it is not an accusation. It is the difference between a formulation and a tested one.
Where the registered evidence comes from
Across both compounds there were five registered studies on 2026-09-18: four naming BPC-157, one naming TB-500.
For BPC-157, reading the four rather than counting them: NCT07803250 (phase 1, rotator-cuff repair, 30 participants, not yet recruiting) and NCT07437547 (phase 2, hamstring strain, 120 participants, recruiting) administer the compound. NCT07752381 is completed but gives a commercial product, "Parlay Recover Peptide Gummies", not BPC-157 as a defined substance. NCT02637284 lists its intervention as "Bepecin" and carries the registry status UNKNOWN, which is what the registry applies when a record goes unmaintained past its own completion date. None has posted results. PubMed filtered to the clinical-trial publication type returns zero records for BPC-157, against 229 overall.
Then there is a pattern in where two of the five come from.
The BPC-157 hamstring study and the TB-500 cardiovascular study share one sponsor, Hudson Biotech. Pulling that sponsor's other filings — a check this library adopted after finding that a compound's evidence base can rest on a single group — returns eight registrations in total, and they have these properties, all readable from the records:
- All eight were first posted between 2026-02-27 and 2026-04-01, inside about five weeks.
- All eight list one location, the same hospital.
- None has been updated on any date later than the day it was first posted. All eight are marked recruiting, and none has posted results.
- Six of the eight share an identical start date — 2026-02-02 — and an identical primary completion date of 2027-02-14, across conditions as unrelated as skin wounds, obesity, prediabetes, hamstring strain, vitiligo and fatty liver disease.
- One is titled *"Tesamorelin for Reduction of Liver Fat in Adults With Fatty Liver Disease (Mock Study)"*.
- One is titled as SURMOUNT-1 with an enrolment of 2,539 — the name and the exact enrolment of Eli Lilly's tirzepatide trial NCT04184622, which is registered to Eli Lilly and recorded as completed.
- The remaining filings name retatrutide, MOTS-c, melanotan II, GHK-Cu and tesamorelin — a portfolio spanning unrelated therapeutic areas.
This entry draws no conclusion about those records beyond what they say, and every detail above is checkable from the identifiers given. What can be said plainly is what a registration is: a filing a sponsor makes describing a study it says it intends to run. It is not a result and it is not a published finding.
The practical point is the one a reader needs. A peptide described as "now in phase 2 trials" is being offered a registration in place of evidence — and registrations vary enormously in what stands behind them. The identifiers above are public, and anyone can read them.
Where it stands
Neither compound is an approved drug in the United States. Both are sold under research-use-only terms, which is a sales designation and not an approval. Both are prohibited at all times in sport under the World Anti-Doping Agency's list; MuscleLedger's page on the same pairing covers detection and the anti-doping position, and counts the preclinical literature.
Questions about use belong with a clinician. This entry describes what the two molecules are and what has been registered about them.
Related entries
- BPC-157 — the 15-residue half
- TB-500 — the 7-residue half
- Thymosin beta-4 — the 43-residue protein TB-500 is cut from
- KLOW — the four-peptide blend built on the same pair
- The peptide bond — the arithmetic that found the acetyl group