IMPORTANCE Antibody blockade of activin type II receptor (ActRII) signaling stimulates skeletal muscle growth. Previous clinical studies suggest that ActRII inhibition with the monoclonal antibody bimagrumab also promotes excess adipose tissue loss and improves insulin resistance.OBJECTIVE To evaluate the efficacy and safety of bimagrumab on body composition and glycemic control in adults with type 2 diabetes and overweight and obesity.
DESIGN, SETTING, AND PARTICIPANTSThis double-masked, placebo-controlled, 48-week, phase 2 randomized clinical trial was conducted among adults with type 2 diabetes, body mass index between 28 and 40, and glycated hemoglobin (HbA 1c ) levels between 6.5% and 10.0% at 9 US and UK sites. The trial was conducted from February 2017 to May 2019. Only participants who completed a full treatment regimen were included in analysis.
INTERVENTIONSPatients were randomized to intravenous infusion of bimagrumab (10 mg/kg up to 1200 mg in 5% dextrose solution) or placebo (5% dextrose solution) treatment every 4 weeks for 48 weeks; both groups received diet and exercise counseling.
MAIN OUTCOMES AND MEASURESThe primary end point was least square mean change from baseline to week 48 in total body fat mass (FM); secondary and exploratory end points were lean mass (LM), waist circumference (WC), HbA 1c level, and body weight (BW) changes from baseline to week 48. RESULTS A total of 75 patients were randomized to bimagrumab (n = 37; 23 [62.2%] women) or placebo (n = 38; 12 [31.6%] women); 58 (77.3%) completed the 48-week study. Patients at baseline had a mean (SD) age of 60.4 (7.7) years; mean (SD) BMI of 32.9 (3.4); mean (SD) BW of 93.6 (14.9) kg; mean (SD) FM of 35.4 (7.5) kg; and mean (SD) HbA 1c level of 7.8% (1.0%). Changes at week 48 for bimagrumab vs placebo were as follows: FM, −20.5% (−7.5 kg [80% CI, −8.3 to −6.6 kg]) vs −0.5% (−0.18 kg [80% CI, −0.99 to 0.63 kg]) (P < .001); LM, 3.6% (1.70 kg [80% CI, 1.1 to 2.3 kg]) vs −0.8% (−0.4 kg [80% CI, −1.0 to 0.1 kg]) (P < .001); WC, −9.0 cm (80% CI, −10.3 to −7.7 cm) vs 0.5 cm (80% CI, −0.8 to 1.7 cm) (P < .001); HbA 1c level, −0.76 percentage points (80% CI, −1.05 to −0.48 percentage points) vs −0.04 percentage points (80% CI, −0.23 to 0.31 percentage points) (P = .005); and BW, −6.5% (−5.9 kg [80% CI, −7.1 to −4.7 kg]) vs −0.8% (−0.8 kg [80% CI, −1.9 to 0.3 kg]) (P < .001). Bimagrumab's safety and tolerability profile was consistent with prior studies.
CONCLUSIONS AND RELEVANCEIn this phase 2 randomized clinical trial, ActRII blockade with bimagrumab led to significant loss of FM, gain in LM, and metabolic improvements during 48 weeks (continued) Key Points Question What are the effects of bimagrumab, an antibody that blocks activin type II receptors and stimulates skeletal muscle growth, on total body fat mass and glycemic control in patients with type 2 diabetes and excess adiposity? Findings In this phase 2 randomized clinical trial of 75 patients with type 2 diabetes and body mass index between 28 and 40 who received bimagrumab or placebo du...