Action Duchenne alongside other foundations supported the pre-clinical development of a novel compound called halofuginone, developed by HALO therapeutics. Halo’s HT-100, an investigational anti-fibrotic for Duchenne, is temporarily on hold in the US following a formal action from the FDA requiring Halo to stop dosing and to not enrol new boys in the phase IIa program. The study was placed on hold at the end of December and since their decision the FDA have met with the study team and they expressed their commitment to working with the lead investigators to allow the program to continue as soon as possible.

The target of the investigational compound, fibrosis, with progressive replacement of muscle tissue, is a prominent feature in some muscular dystrophies, preventing complete regeneration and hampering muscle functions. Halofuginone, an inhibitor of Smad3 phosphorylation downstream of TGF signaling, inhibits the activation of fibroblasts and their ability to synthesize the extracellular matrix. In animal models of duchenne and other muscular dystrophies with prominent muscle fibrosis, halofuginone treatment has resulted in both prevention of collagen production in young animals and resolution of established fibrosis in older ones: the reduction in muscle collagen content was associated with improved muscle histopathology and major improvements in muscle function.