Effect of bimagrumab on thigh muscle volume and composition in men with casting-induced atrophy.
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ABSTRACT: BACKGROUND:Patients experiencing disuse atrophy report acute loss of skeletal muscle mass which subsequently leads to loss of strength and physical capacity. In such patients, especially the elderly, complete recovery remains a challenge even with improved nutrition and resistance exercise. This study aimed to explore the clinical potential of bimagrumab, a human monoclonal antibody targeting the activin type II receptor, for the recovery of skeletal muscle volume from disuse atrophy using an experimental model of lower extremity immobilization. METHODS:In this double-blind, placebo-controlled trial, healthy young men (n = 24; mean age, 24.1 years) were placed in a full-length cast of one of the lower extremities for 2 weeks to induce disuse atrophy. After cast removal, subjects were randomized to receive a single intravenous (i.v.) dose of either bimagrumab 30 mg/kg (n = 15) or placebo (n = 9) and were followed for 12 weeks. Changes in thigh muscle volume (TMV) and inter-muscular adipose tissue (IMAT) and subcutaneous adipose tissue (SCAT) of the thigh, maximum voluntary knee extension strength, and safety were assessed throughout the 12 week study. RESULTS:Casting resulted in an average TMV loss of -4.8% and comparable increases in IMAT and SCAT volumes. Bimagrumab 30 mg/kg i.v. resulted in a rapid increase in TMV at 2 weeks following cast removal and a +5.1% increase above pre-cast levels at 12 weeks. In comparison, TMV returned to pre-cast level at 12 weeks (-0.1%) in the placebo group. The increased adiposity of the casted leg was sustained in the placebo group and decreased substantially in the bimagrumab group at Week 12 (IMAT: -6.6%, SCAT: -3.5%). Knee extension strength decreased by ~25% in the casted leg for all subjects and returned to pre-cast levels within 6 weeks after cast removal in both treatment arms. Bimagrumab was well tolerated with no serious or severe adverse events reported during the study. CONCLUSIONS:A single dose of bimagrumab 30 mg/kg i.v. safely accelerated the recovery of TMV and reversal of accumulated IMAT following 2 weeks in a joint-immobilizing cast.
SUBMITTER: Rooks DS
PROVIDER: S-EPMC5659065 | biostudies-literature | 2017 Oct
REPOSITORIES: biostudies-literature
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