Activin Type II Receptor Blockade for Treatment of Muscle Depletion in Chronic Obstructive Pulmonary Disease. A Randomized Trial

Rationale: Bimagrumab is a fully human monoclonal antibody that blocks the activin type II receptors, preventing the activity of myostatin and other negative skeletal muscle regulators.Objectives: To assess the effects of bimagrumab on skeletal muscle mass and function in patients with chronic obstructive pulmonary disease (COPD) and reduced skeletal muscle mass.Methods: Sixty-seven patients with COPD (mean FEV1, 1.05 L [41.6% predicted]; aged 40–80 yr; body mass index < 20 kg/m2 or appendicular skeletal muscle mass index ≤ 7.25 [men] and ≤ 5.67 [women] kg/m2), received two doses of either bimagrumab 30 mg/kg intravenously (n = 33) or placebo (n = 34) (Weeks 0 and 8) over 24 weeks.Measurements and Main Results: We assessed changes in thigh muscle volume (cubic centimeters) as the primary endpoint along with 6-minute-walk distance (meters), safety, and tolerability. Fifty-five (82.1%) patients completed the study. Thigh muscle volume increased by Week 4 and remained increased at Week 24 in bimagrumab-treat...