TB-500

Thymosin Beta-4 Synthetic Fragment

Evidence & Status

  • Preliminary / Experimental
  • Preliminary

At a Glance

A synthetic heptapeptide corresponding to the actin-binding motif LKKTETQ (residues 17–23 of thymosin beta-4). This record covers the LKKTETQ fragment only — not full-length thymosin beta-4, which is a distinct 43-amino-acid protein. Studied in preclinical models for wound healing, anti-inflammatory, and tissue repair effects.

Plain English

TB-500 refers to the seven-amino-acid LKKTETQ fragment derived from the actin-binding region of the larger thymosin beta-4 protein. It is not the same molecule as full-length thymosin beta-4. Researchers study this fragment because the LKKTETQ sequence appears to coordinate cellular repair processes in preclinical models — including cell migration, new blood vessel formation, and inflammation modulation. Most foundational research has been conducted in animal models. No adequate human interventional evidence specific to the LKKTETQ fragment was identified in this review.

Overview

TB-500 is identified by FDA as the N-terminally acetylated seven-amino-acid fragment Ac-LKKTETQ (free base; UNII QHK6Z47GTG, CAS 885340-08-9), characterized in the July 2026 FDA Pharmacy Compounding Advisory Committee briefing document with a molecular weight of 889.01 g/mol. This free-base form is distinct from TB-500 acetate (C₃₈H₆₈N₁₀O₁₄·CH₃COOH, MW 949.1 g/mol) and from full-length 43-amino-acid thymosin beta-4. Evidence and human trials of full-length thymosin beta-4 must not be transferred to this distinct fragment.

Research Summary

No adequate human interventional evidence specific to the LKKTETQ fragment was identified in this review. Full-length thymosin beta-4 research is an entity mismatch and is excluded from this record. A July 2026 Pharmacy Compounding Advisory Committee discussion was advisory only and does not constitute FDA approval or a final FDA determination.

Research Areas

  • Muscle repair
  • Angiogenesis
  • Inflammation
  • Cardiac repair
  • Wound healing

Safety & Risks

Serious Risks

  • Human safety, pharmacokinetics, and long-term outcomes for the LKKTETQ fragment have not been established

Reported Side Effects

  • Injection site discomfort
  • Temporary fatigue
  • Headache (rare)
United States
Research only
United Kingdom
Research only
Australia
Research only
Canada
Research only

Citations & Sources