TB-500 (Thymosin Beta-4 Fragment)

Sequence

Mechanism of Action

The marketed "TB-500" is a 7-residue fragment of the 43-amino-acid protein Thymosin Beta-4, but nearly all of the mechanistic and efficacy literature — angiogenesis, wound healing, and myoblast chemotaxis — was conducted with the full-length protein, not the fragment; only one identified study characterizes the fragment itself, and it is an analytical detection method paper, not an efficacy or safety study. Full-length Thymosin Beta-4 is an intracellular actin-monomer-binding protein that promotes cell migration and angiogenesis, partly via VEGF induction. This same pro-angiogenic mechanism has a documented dark side: full-length Tβ4-overexpressing tumor cells produced significantly larger tumors and more metastases in an animal cancer model, a legitimate mechanistic safety consideration given TB-500 is marketed on the identical mechanism.

Research Literature