improvement in muscle function was seen, however, the studywas not powered to detect these changes [47]. Another pub-lication described the single muscle fiber contractile propertiesof 5 individuals with different forms of muscle dystrophy thatwere treated with MYO-029 and 1 who was treated withplacebo. These individuals were part of the larger trial previ-ously mentioned and had muscle biopsies before and aftertreatment. The authors noted an improvement in contractileproperties in the isolated single muscle fibers in most of theindividuals treated with MYO-029 compared with placebo butno difference in manual muscle function testing [54]. The onlypublished and peer reviewed randomized, placebo controlledtrial in healthy adults used the compound ACE-031, a solubleActRIIB decoy receptor [55•]. The study published by Attieand colleagues enrolled 48 healthy postmenopausal femaleswho received varying doses of ACE-031 or placebo (3:1ratio). One subcutaneous dose was administered at the begin-ning of the trial and participants were followed for 57 days.The aim of this phase I study was to examine safety andpharmaco-kinetics/dynamics. The study also included explor-atory end points such as muscle mass, fat mass, and laboratorymarkers including bone turnover markers. Baseline hand gripstrength was listed in the demographics but changes over timewere not described. No other muscle function parameters werereported. The compound was generally well tolerated with themost common adverse events being lipase elevation, head-aches, injection site erythema, orthostatic hypotension, andincreased cholesterol levels. These adverse events were clas-sified as mild [55•]. Muscle mass as measured by MRI andDXA body composition increased significantly (~3 %) in thetreatment groups compared with placebo. It should be notedthat the results of a phase 1b trial of ACE-031 (clinicaltrials.gov NCT00952887) have been presented in abstract form andare summarized on the company website (http://www.acceleronpharma.com/2010/10/acceleron-presents-preliminary-ace-031-results-from-a-phase-1-multiple-ascending-dose-study-in-healthy-volunteers/). This trialenrolled 60 healthy postmenopausal females and randomizedparticipants in 6 groups of placebo and varying doses andinjection intervals of ACE-031 [56]. Increases in muscle masson DXA and MRI in the range of 4 %–5 % were seen after36 days. No improvements in grip strength or functional testswere found. These small studies are essentially proof of con-cept and indicate the potential for such an approach to increasemuscle mass.
Myostatin - The Holy Grail for Muscle, Bone, and Fat? (PDF Download Available). Available from: https://www.researchgate.net/publication/257135787_Myostatin_-_The_Holy_Grail_for_Muscle_Bone_and_Fat [accessed Apr 24, 2016].