A Phase 1 interventional study of MBX 4291 and Placebo in Obesity, sponsored by MBX Biosciences. Recruiting at 4 sites in United States. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-06-09.
Sponsored by MBX Biosciences · Phase 1, Interventional, and Treatment
The purpose of this study is to evaluate the safety and tolerability of single and multiple subcutaneous (SC) doses of MBX 4291 in adults with obesity.
This is a Phase 1, double-blind, placebo-controlled first-in-human study to evaluate the single ascending doses (SAD) and multiple ascending doses (MAD) of MBX 4291 in participants with obesity, who are otherwise generally healthy. Approximately 124 patients aged 18 to 65 years old will be enrolled.
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 124 is above the median of 67 across 9,006 interventional studies indexed under Obesity.
Browse Obesity studies →MBX Biosciences is the lead sponsor of 8 studies on the registry; 2 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be administered single ascending doses of MBX 4291, or matching placebo.
Drug: MBX 4291
Participants will be administered multiple ascending doses of MBX 4291, or matching placebo.
Drug: MBX 4291
Participants will be administered multiple ascending doses of MBX 4291, or matching placebo.
Drug: MBX 4291
Participants will be administered single or multiple ascending doses of placebo.
Drug: Placebo
MBX 4291 will be administered subcutaneously (SC)
Placebo: Placebo will be administered subcutaneously (SC)
Number of participants with Treatment Emergent Adverse Events (TEAEs)
Time frame: The total duration of study participation for each participant including screening, treatment period, follow-up, and end of study visit will be up to 91 days in Part A, up to 99 days in Part B, and up to 148 days in Part C.
Started Sep 2025 (actual). Primary completion is estimated for Oct 2026, 13 months after the start.
Of 334 industry-sponsored phase 1 interventional studies under Obesity, half reached primary completion within 9 months of starting (the median), counting those still running; a quarter within 5 and three quarters within 15. This study's planned 13 months is above that.
Counting every sponsor, half of 439 studies reached it within 11 months; a quarter within 6 and three quarters within 24.
How these figures are worked out, and which studies are left out of them.
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