ACE-031 vs IGF-DES

Soluble decoy receptor for ActRIIB; sequesters myostatin, activin, and GDF-11 to remove multiple brakes on muscle and bone growth simultaneously

A soluble decoy receptor that blocks the ActRIIB pathway, inhibiting myostatin and related TGF-β family proteins. Produces dramatic muscle and bone gains but carries cardiovascular risks at high doses.

N-terminal truncation eliminates IGFBP binding, leaving nearly all circulating IGF-DES unbound and active. Results in substantially higher tissue IGF-1R activation versus native IGF-1 at equivalent doses. Activates PI3K/Akt/mTOR for muscle hypertrophy and satellite cell proliferation.

A truncated form of IGF-1 with the first 3 amino acids removed. Does not bind IGF binding proteins (IGFBPs), resulting in dramatically higher free active concentration at tissue level. Considered highly anabolic with limited systemic safety data in humans.