ACE-031 is a soluble activin receptor IIB (ActRIIB) fusion protein studied as a myostatin inhibitor for increasing muscle mass, most notably in a clinical trial for Duchenne muscular dystrophy. That trial was discontinued in 2013 after participants developed nosebleeds and visible small blood vessel dilation (telangiectasia).
A real human trial — halted for safety reasons
ACE-031 is a soluble activin receptor type IIB fusion protein that binds myostatin, developed for muscle-wasting conditions.
Randomized, placebo-controlled, ascending-dose trial in ambulatory boys with Duchenne muscular dystrophy, subcutaneous dosing every 2-4 weeks: the trial showed trends toward positive effects on lean mass, fat mass, bone density, and 6-minute walk test — but was halted after the second dosing regimen due to safety concerns: epistaxis (nosebleeds) and telangiectasias (abnormal small blood vessel dilation), both non-muscle-related adverse events. Campbell et al., Muscle Nerve, 2017 The sponsor companies (Acceleron Pharma, Shire) discontinued the entire ACE-031 program in 2013 and did not resume development.
Side Effects
The defining safety finding for this compound is the epistaxis/telangiectasia signal above — real enough to end a promising muscle-mass/strength trial early, in a pediatric population, despite otherwise-positive efficacy trends. Worth leading with this, not treating it as a footnote.
Is ACE-031 FDA-approved?+
No. Its furthest clinical development was a Duchenne muscular dystrophy trial that was discontinued in 2013 over safety concerns, and it has no approved indication.
Why was the ACE-031 trial stopped?+
Participants developed nosebleeds and skin/vascular changes (telangiectasia) linked to its effect on blood vessels, which led the trial to be halted.
What is ACE-031 researched for?+
Inhibiting myostatin, a natural brake on muscle growth, to increase muscle mass — originally investigated for muscle-wasting conditions.
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