ACE-031 functions as a soluble ActRIIB ligand trap, binding multiple ActRIIB ligands including myostatin, activins, GDF-11, BMP-9, and BMP-10. This broad ligand-binding profile allows investigation of combined ActRIIB pathway suppression rather than isolated myostatin inhibition.

In contrast, myostatin-selective approaches target GDF-8 specifically, making ACE-031 a valuable tool for studying the integrated contribution of multiple ActRIIB ligands to signalling, tissue regulation, and pathway cross-talk.

ACE-031 acts upstream as a receptor-based ligand trap that sequesters multiple ActRIIB-binding growth factors, whereas myostatin-specific antibodies selectively neutralize GDF-8 alone. This distinction allows researchers to compare broad ActRIIB pathway inhibition with highly selective myostatin blockade and evaluate the biological consequences of each approach across different experimental systems.

Common endpoints include skeletal muscle mass, muscle fibre morphology, muscle function measurements, ActRIIB pathway biomarkers, Smad2/3 signalling activity, bone-related signalling markers, and expression of genes regulated by myostatin and activin pathways. These endpoints help characterize the effects of broad ActRIIB ligand sequestration and distinguish pathway-specific from multi-ligand responses.