What is Bimagrumab?

A monoclonal antibody that blocks activin type II receptors, studied by Lilly (via Versanis) to cut fat while keeping muscle during GLP-1 weight loss.

Bimagrumab in the library · Metabolic & Weight Peptides · Human Trials · What are peptides?

17 registered trials · 17 indexed papers · 4 human / 2 animal studies

From the PeptideWhiz library entry. "As described" sections summarize claims made in the sources; they are not PeptideWhiz endorsements.

What it is

Bimagrumab is described as a full-size human monoclonal antibody (about 150 kDa) against activin type II receptors, given by IV infusion in trials.

Identity note on "Bimagrumab Frag": some research sellers list a "Bimagrumab Frag" as a small lyophilized peptide. Bimagrumab is an antibody, not a peptide, and no defined, published "fragment" of it exists. Such products cannot be the studied drug, and what they contain is unknown unless independent testing shows it.

Mechanism (as described)

  • Blocking ActRII signaling (myostatin, activins) is described as increasing skeletal muscle and reducing fat mass (Petricoul et al., 2023).

Evidence (as described)

  • A phase 2 trial in adults with type 2 diabetes and obesity reported fat-mass loss with lean-mass gain versus placebo (Heymsfield et al., 2021). The phase 2 BELIEVE trial tested it with semaglutide in obesity (Heymsfield et al., Nat Med 2026). A meta-analysis summarized body-composition effects (Kanbay et al., 2024).

Status

Investigational (phase 2). Not approved anywhere.

Registered human trials (17)

TrialPhaseStatusYearEnrolled
Effect of Tirzepatide and Bimagrumab on Body Composition, Insulin Sensitivity, and Bone in Adults With ObesityPhase 2recruiting202563
A Study of Bimagrumab Alone (LY3985863) and Bimagrumab With Tirzepatide (LY900042) in Healthy ParticipantsPhase 1completed2025125
A Study of Bimagrumab (LY3985863) and Tirzepatide (LY3298176), Alone or in Combination, in Participants With Obesity or Overweight With Type 2 DiabetesPhase 2withdrawn2025
A Study to Investigate Weight Management With Bimagrumab (LY3985863) and Tirzepatide (LY3298176), Alone or in Combination, in Adults With Obesity or OverweightPhase 2active not recruiting2024252
Safety and Efficacy of Bimagrumab and Semaglutide in Adults Who Are Overweight or ObesePhase 2completed2022507
Safety, Pharmacokinetics and Efficacy of Bimagrumab in Overweight and Obese Patients With Type 2 DiabetesPhase 2completed201778
A 24-week Off-drug Extension Study in Sarcopenic Elderly Who Completed Treatment in the 6-month Core StudyPhase 2completed2015160
An Extension Study of the Efficacy, Safety and Tolerability of BYM338 (Bimagrumab) in Patients With Sporadic Inclusion Body Myositis Who Previously Participated in the Core Study CBYM338B2203Phase 3completed2015211
Study of Muscle Effects of BYM338 in Mechanically Ventilated PatientsPhase 2withdrawn2014
Study of Efficacy and Safety of Bimagrumab in Patients After Hip Fracture SurgeryPhase 2completed2014251
Study of Long-term Safety, Efficacy Tolerability of BYM338 in Patients With Sporadic Inclusion Body MyositisPhase 2/Phase 3completed201410
Dose Range Finding Study of Bimagrumab in SarcopeniaPhase 2completed2014217
Efficacy and Safety of Bimagrumab/BYM338 at 52 Weeks on Physical Function, Muscle Strength, Mobility in sIBM PatientsPhase 2/Phase 3completed2013251
A Multi-center Study to Assess the Effects of BYM338 on Skeletal Muscle in Sarcopenic AdultsPhase 2completed201240
BYM338 in Chronic Obstructive Pulmonary Disease (COPD) Patients With CachexiaPhase 2completed201267
Efficacy, Safety and Tolerability of BYM338 in Patients With Sporadic Inclusion Body MyositisPhase 2completed201114
Clinical Study of BYM338 for the Treatment of Unintentional Weight Loss in Patients With Cancer of the Lung or the PancreasPhase 2completed201157

Peer-reviewed studies (17)

PaperAuthorsJournalYearType
Cardiac safety of chronic inhibition of the myostatin-activin pathway with bimagrumab in healthy older adultsRooks D et al.The Journal of clinical endocrinology and metabolism2026Randomized Controlled Trial
Bimagrumab plus semaglutide alone or in combination for the treatment of obesity: a randomized phase 2 trialHeymsfield SB et al.Nature medicine2026Randomized Controlled Trial
Pharmacokinetics and Pharmacodynamics of Bimagrumab (BYM338)Petricoul O et al.Clinical pharmacokinetics2023Randomized Controlled Trial
Bimagrumab to improve recovery after hip fracture in older adults: a multicentre, double-blind, randomised, parallel-group, placebo-controlled, phase 2a/b trialHofbauer LC et al.The lancet. Healthy longevity2021Randomized Controlled Trial
Efficacy and Safety of Bimagrumab in Sporadic Inclusion Body Myositis: Long-term Extension of RESILIENTAmato AA et al.Neurology2021Randomized Controlled Trial
Effect of Bimagrumab vs Placebo on Body Fat Mass Among Adults With Type 2 Diabetes and Obesity: A Phase 2 Randomized Clinical TrialHeymsfield SB et al.JAMA network open2021Randomized Controlled Trial
Safety and pharmacokinetics of bimagrumab in healthy older and obese adults with body composition changes in the older cohortRooks D et al.Journal of cachexia, sarcopenia and muscle2020Randomized Controlled Trial
Bimagrumab vs Optimized Standard of Care for Treatment of Sarcopenia in Community-Dwelling Older Adults: A Randomized Clinical TrialRooks D et al.JAMA network open2020Randomized Controlled Trial
Long-term safety and tolerability of bimagrumab (BYM338) in sporadic inclusion body myositisSivakumar K et al.Neurology2020Clinical Trial
[Late phase II/III study of BYM338 in patients with sporadic inclusion body myositis (RESILIENT): Japanese cohort data]Mori-Yoshimura M et al.Rinsho shinkeigaku = Clinical neurology2019Clinical Trial, Phase III
Safety and efficacy of intravenous bimagrumab in inclusion body myositis (RESILIENT): a randomised, double-blind, placebo-controlled phase 2b trialHanna MG et al.The Lancet. Neurology2019Randomized Controlled Trial
Activin Type II Receptor Blockade for Treatment of Muscle Depletion in Chronic Obstructive Pulmonary Disease. A Randomized TrialPolkey MI et al.American journal of respiratory and critical care medicine2019Randomized Controlled Trial
Effects of bimagrumab, an activin receptor type II inhibitor, on pituitary neurohormonal axesGarito T et al.Clinical endocrinology2018Randomized Controlled Trial
Bimagrumab improves body composition and insulin sensitivity in insulin-resistant individualsGarito T et al.Diabetes, obesity & metabolism2018Randomized Controlled Trial
Effect of bimagrumab on thigh muscle volume and composition in men with casting-induced atrophyRooks DS et al.Journal of cachexia, sarcopenia and muscle2017Randomized Controlled Trial
Treatment of Sarcopenia with Bimagrumab: Results from a Phase II, Randomized, Controlled, Proof-of-Concept StudyRooks D et al.Journal of the American Geriatrics Society2017Randomized Controlled Trial
Treatment of sporadic inclusion body myositis with bimagrumabAmato AA et al.Neurology2014Randomized Controlled Trial

More cited research

Conditions researched

Related compounds

FAQ

What is Bimagrumab?

A monoclonal antibody that blocks activin type II receptors, studied by Lilly (via Versanis) to cut fat while keeping muscle during GLP-1 weight loss.

How many registered human trials study Bimagrumab?

The PeptideWhiz trial index lists 17 registered trials for Bimagrumab, the most recent from 2025.

How much published research exists on Bimagrumab?

The PeptideWhiz paper index links 17 PubMed papers to Bimagrumab; by study type, 4 human and 2 animal studies.

Which conditions is Bimagrumab researched for?

Fat loss, obesity & body recomposition, Insulin resistance, prediabetes & type 2 diabetes, Lung health, asthma & COPD, Muscle gain, sarcopenia & building muscle after 40, Muscle disease (myopathy), Osteoporosis and bone density, Post-surgical inflammation and surgery recovery.

Research and education only. Not medical advice. No dosing guidance. Data: ClinicalTrials.gov registry and PubMed via the PeptideWhiz index (204,289 studies).

Reported dosing ranges from research