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Bim3.9
Bimagrumab Research
Mostly mechanism / observationalLimited safety
5 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Bimagrumab studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality meta-analyses and randomised trials published 2014–2025 with a typical study size of 75 participants.
Based on 5 studies · 1 meta-analysis · 4 RCTs · 340 total participants
Confidence
Moderate
By outcome
Muscle & lean mass
Mostly mechanism / observational4 studies
Safety profile
Mostly mechanism / observational3 studies
Fat loss & metabolic
Too few graded studies1 study
Active research area
2 studies in the last 5 years · Latest meta-analysis: 2025
201420192025
1RCTn=251 · medium study2019
At week 52, 6MWD change from baseline did not differ between any bimagrumab dose and placebo (least squares mean treatment difference for bimagrumab 10 mg/kg group, 17·6 m... p=0·22).
Hanna MG, Badrising UA, Benveniste O, Lloyd TE, Needham M, Chinoy H, Aoki M, Machado PM, Liang C, Reardon KA, de Visser M, Ascherman DP, Barohn RJ, Dimachkie MM. · Lancet Neurol (2019)
The load-bearing counter-evidence: the pivotal phase 2b RESILIENT trial randomized 251 inclusion-body-myositis patients across 38 sites to bimagrumab (1, 3, or 10 mg/kg) or placebo, IV every 4 weeks, with 6-minute walking distance at 52 weeks as the primary endpoint
FAILED its primary endpoint — 6MWD did not differ from placebo at any dose (10 mg/kg difference 17.6 m, p=0.22), despite the drug's known muscle-mass effect
Muscle spasms (40-68%) and diarrhoea (32-52%) were the most frequent adverse events with bimagrumab; falls were common across all groups (a feature of the disease)
ActRII blockade with bimagrumab led to significant loss of FM, gain in LM, and metabolic improvements during 48 weeks in patients with overweight or obesity who had type 2 diabetes.
Heymsfield SB, Coleman LA, Miller R, Rooks DS, Laurent D, Petricoul O, Praestgaard J, Swan T, Wade T, Perry RG, Goodpaster BH, Roubenoff R. · JAMA Netw Open (2021)
The headline metabolic trial: a double-masked, placebo-controlled, 48-week phase 2 RCT in 75 adults with type 2 diabetes and obesity, given monthly intravenous bimagrumab (10 mg/kg, up to 1200 mg) or placebo plus diet/exercise counselling
Bimagrumab produced a large loss of total body fat mass (~20.5% relative reduction) and a gain in lean mass (~3.6%) versus placebo at week 48 — a striking fat-down/lean-up body recomposition
Also reduced waist circumference and body weight (-6.5%) and improved HbA1c versus placebo; safety/tolerability was consistent with prior studies
Trials of methotrexate... bimagrumab, arimoclomol, and sirolimus provided low-quality to high-quality evidence of having no effect on the progression of IBM.
Santos EJF, Farisogullari B, Yapp N, Townsley H, Sousa P, Machado PM. · RMD Open (2025)
Top-of-pyramid synthesis: a Cochrane-method systematic review (with meta-analysis where possible) of randomized trials of pharmacological treatments for inclusion-body myositis
Concluded that the trialed drugs — including bimagrumab — showed evidence of having no effect on the progression of IBM
Reinforces the RESILIENT result at the synthesis level: no IBM drug, bimagrumab included, has been shown to change disease course
Eight weeks after dosing, the bimagrumab-treated patients increased thigh muscle volume (right leg +6.5% compared with placebo, p = 0.024)... and lean body mass (+5.7% compared with placebo, p = 0.014).
Amato AA, Sivakumar K, Goyal N, David WS, Salajegheh M, Praestgaard J, Lach-Trifilieff E, Trendelenburg AU, Laurent D, Glass DJ, Roubenoff R, Tseng BS, Greenberg SA. · Neurology (2014)
The proof-of-concept human trial: a randomized controlled pilot in 14 sporadic inclusion-body-myositis patients given a single dose of bimagrumab (n=11) or placebo (n=3), with thigh-muscle volume by MRI at 8 weeks as the primary outcome
Bimagrumab increased thigh-muscle volume (+6.5% right, +7.6% left) and lean body mass (+5.7%) versus placebo, and 6-minute walking distance improved, peaking at +14.6% at 16 weeks (p=0.008)
Established that ActRII blockade builds muscle in humans (Class I evidence); the main adverse events were mild acne and transient involuntary muscle contractions
Bimagrumab alters the function of pituitary gonadotroph cells, consistent with blockade of activin on local ActRII. This effect is reversible with clearance of bimagrumab.
Garito T, Zakaria M, Papanicolaou DA, Li Y, Pinot P, Petricoul O, Laurent D, Rooks D, Rondon JC, Roubenoff R. · Clin Endocrinol (Oxf) (2018)
Mechanistic/safety RCT: healthy adults aged 55-75 received IV bimagrumab 10 mg/kg or placebo, with pituitary-gonadal and pituitary-adrenal function assessed by GnRH and ACTH stimulation tests
In women, FSH levels were reduced by 42.16 IU/L (P<.001) and LH increased, consistent with blockade of activin signalling at the pituitary; effects were reversible after the antibody cleared
Gonadal and adrenal androgen levels were not affected — the neurohormonal effect was specific to the gonadotroph FSH/LH axis and transient