Actively Recruiting
Effect of Tirzepatide and Bimagrumab on Body Composition, Insulin Sensitivity, and Bone in Adults With Obesity
Led by Massachusetts General Hospital · Updated on 2026-03-27
63
Participants Needed
1
Research Sites
177 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
In adults with obesity seeking treatment, weight loss would ideally be composed almost exclusively of fat mass. However, loss of muscle mass and bone are unintentional consequences of weight loss, which may have negative effects on health by lessening improvements in glucose and insulin levels, reducing resting metabolic rate, and increasing the risk of falls and fractures. Data in animals and humans suggest that bimagrumab, an investigational new drug for obesity that inhibits the activin type II receptor (ActRII) inhibitor, may help maximize loss of fat mass while maintaining muscle mass when used in combination with a glucagon-like peptide 1 receptor agonist (GLP-1 RA). The investigators hypothesize that in a randomized, placebo-controlled trial of 63 adults with obesity randomized to tirzepatide (GLP-1/GIP RA) + bimagrumab, tirzepatide alone, or bimagrumab alone, the combination of tirzepatide + bimagrumab will result in improvements in muscle, fat, and bone compared to tirzepatide alone or bimagrumab alone when given in addition to a lifestyle intervention for weight loss over 52 weeks.
CONDITIONS
Official Title
Effect of Tirzepatide and Bimagrumab on Body Composition, Insulin Sensitivity, and Bone in Adults With Obesity
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Adults with BMI 30 kg/m2 or higher, or BMI 27 kg/m2 or higher with at least one weight-related medical condition
- History of at least one unsuccessful behavioral effort to lose body weight
- Have an established primary care provider
You will not qualify if you...
- Current or past diabetes mellitus or use of diabetes medication, HbA1c ≥6.5%, or fasting glucose ≥126 mg/dL
- Single serum transaminase level (ALT, AST, alk phos) ≥3 times upper limit of normal
- Serum lipase and/or amylase levels ≥2 times upper limit of normal
- Serum bilirubin level greater than 1.6 mg/dL
- Chronic kidney disease with estimated glomerular filtration rate less than 45 mL/min
- Low blood counts: WBC less than 3000/µL, neutrophils less than 1500/µL, hemoglobin less than 12 g/dL, or platelet count less than 100,000/µL
- Significant coagulopathy (PT/INR >1.5)
- History of familial hypertriglyceridemia or serum fasting triglyceride greater than 500 mg/dL
- Uncontrolled thyroid disease with abnormal TSH and free T4
- Any chronic active infection such as HIV, hepatitis B or C, or recent hepatitis C treatment
- Severe active liver disease or conditions with hepatotoxic potential
- Active significant gastric emptying abnormality or chronic use of drugs affecting gastrointestinal motility
- History of calcium oxalate kidney stones
- History of serious heart conditions including arrhythmias, angina, heart attack, stroke, heart surgery, heart failure, valve disorders, pulmonary hypertension, chronic hypotension or uncontrolled hypertension
- Heart rate over 100 bpm after 5 minutes resting
- History of cancer within past 5 years except certain skin cancers
- Current significant psychiatric disease or recent suicide attempt
- PHQ-9 score 15 or higher at screening
- Personal or family history of certain endocrine cancers
- Active alcohol, drug, or tobacco abuse exceeding specified limits
- Frequent cannabis/THC use unwilling to abstain during study
- Obesity caused by other endocrine disorders or genetic syndromes
- History or planned weight loss surgery during trial
- Use of anti-obesity medications or supplements within past 6 months
- Recent new dietary or exercise weight loss program within 3 months
- Weight instability over 5 kg within 3 months
- Weight over 150 kg due to imaging limitations
- Use of medications causing weight gain or muscle anabolic agents recently or during study
- Recent glucose-lowering treatments
- Hypersensitivity to monoclonal antibodies or similar drugs
- History of fragility fracture or low bone density in older participants
- Use of certain osteoporosis treatments recently or during study
- Unable or unwilling to follow dietary and lifestyle intervention including exercise
- Women who are pregnant or breastfeeding
- Women of child-bearing potential not using required contraception
- Men with low morning testosterone levels
- Participation in other incompatible medical research
- Plans to move away or be absent for extended periods during study
- Routine MRI exclusion
- Recent blood or plasma donation
- Major surgery planned during trial
- Any condition judged by investigator to risk safety or protocol compliance
AI-Screening
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Trial Site Locations
Total: 1 location
1
Massachusetts General Hospital
Boston, Massachusetts, United States, 02114
Actively Recruiting
Research Team
M
Melanie S Haines, MD
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
QUADRUPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
3
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