ObesityPhase 1NCT07142707
A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of MBX 4291 in Adult Participants With Obesity
A Phase 1 study testing MBX 4291 in people with Obesity, run by MBX Biosciences at 4 sites in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obesity
- What is being tested?
- MBX 4291
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 124 participants
- Where
- 4 sitesUnited States
- Study dates
- 3 Sep 2025to 30 Oct 2026
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age of >18 to ≤65 years at the time of signing the informed consent.
- Has a BMI of ≥30 to <50 kg/m2 at screening and baseline.
- Weight-stable, i.e., no more than ±5% change in body weight for at least 3 months prior to screening and between screening and baseline.
Who cannot join
- History of, or currently active, significant illness or medical disorders that in the opinion of the investigator may preclude participants from participating in the study.
- History of currently active pancreatitis, type I and type II diabetes.
- Secondary causes of obesity, including but not limited to hypothalamic, monogenic, syndromic, or endocrine causes.
- A personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2.
Trial locations and contacts
4 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States4 sites, 4 recruiting
- Recruiting
MBX Biosciences Investigational Site
Doral, Florida, 33172
- Recruiting
MBX Biosciences Investigational Site
Kansas City, Missouri, 64114
- Recruiting
MBX Biosciences Investigational Site
Knoxville, Tennessee, 37920
- Recruiting
MBX Biosciences Investigational Site
Lexington, Kentucky, 40509
About this study
Official title: A Randomized, Double-blind, Placebo-controlled First-in-human Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single and Multiple Ascending Doses of MBX 4291 in Adult Participants With Obesity
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.
Read the detailed description
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.
- Conditions
- Obesity
- Being tested
- MBX 4291, Placebo
- Keywords
- Body Weight, Body Mass Index, Overweight, Nutrition Disorders
- Medical subject headings
- Obesity, Body Weight, Overweight, Nutrition Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
MBX 4291Drug
MBX 4291 will be administered subcutaneously (SC)
PlaceboDrug
Placebo: Placebo will be administered subcutaneously (SC)
| Study group | Role | What they receive |
|---|---|---|
| MBX 4291 (Part A) | Experimental | Participants will be administered single ascending doses of MBX 4291, or matching placebo. Receives: Drug: MBX 4291 |
| MBX 4291 (Part B) | Experimental | Participants will be administered multiple ascending doses of MBX 4291, or matching placebo. Receives: Drug: MBX 4291 |
| MBX 4291 (Part C) | Experimental | Participants will be administered multiple ascending doses of MBX 4291, or matching placebo. Receives: Drug: MBX 4291 |
| Placebo | Placebo comparator | Participants will be administered single or multiple ascending doses of placebo. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with Treatment Emergent Adverse Events (TEAEs)
Measured: 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.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Aug 2025
- Study start3 Sep 2025
- Primary completion30 Oct 2026 (estimated)
- Study completion30 Oct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 124 participants (estimated)
Sponsor and investigators
- Lead sponsor
- MBX Biosciences
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07142707
- Sponsor's protocol ID
- MBX-4O3001
- Status last verified
- Jun 2026
- First submitted
- 4 Aug 2025
- Last updated
- 9 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized, Double-blind, Placebo-controlled First-in-human Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single and Multiple Ascending Doses of MBX 4291 in Adult Participants With Obesity
- ClinicalTrials.gov ID
- NCT07142707
- Acronym / sponsor ID
- MBX-4O3001
- Conditions
- Obesity
- Keywords
- Body Weight, Body Mass Index, Overweight, Nutrition Disorders
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 124 participants (estimated)
- Lead sponsor
- MBX BiosciencesIndustry (pharma, biotech, devices)
- Study start
- 3 Sep 2025 (actual)
- Primary completion
- 30 Oct 2026 (estimated)
- Study completion
- 30 Oct 2026 (estimated)
- First posted
- 27 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| MBX 4291 (Part A) | Experimental | Drug: MBX 4291Participants will be administered single ascending doses of MBX 4291, or matching placebo. |
| MBX 4291 (Part B) | Experimental | Drug: MBX 4291Participants will be administered multiple ascending doses of MBX 4291, or matching placebo. |
| MBX 4291 (Part C) | Experimental | Drug: MBX 4291Participants will be administered multiple ascending doses of MBX 4291, or matching placebo. |
| Placebo | Placebo comparator | Drug: PlaceboParticipants will be administered single or multiple ascending doses of placebo. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Age of >18 to ≤65 years at the time of signing the informed consent.
- Has a BMI of ≥30 to <50 kg/m2 at screening and baseline.
- Weight-stable, i.e., no more than ±5% change in body weight for at least 3 months prior to screening and between screening and baseline.
Key exclusion criteria (4 listed)
- History of, or currently active, significant illness or medical disorders that in the opinion of the investigator may preclude participants from participating in the study.
- History of currently active pancreatitis, type I and type II diabetes.
- Secondary causes of obesity, including but not limited to hypothalamic, monogenic, syndromic, or endocrine causes.
- A personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| MBX 4291MBX 4291 will be administered subcutaneously (SC) | Drug | MBX 4291 (Part A), MBX 4291 (Part B), MBX 4291 (Part C) |
| PlaceboPlacebo: Placebo will be administered subcutaneously (SC) | Drug | Placebo |
Primary outcome
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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing MBX 4291 in people with Obesity, run by MBX Biosciences at 4 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Elisa Fabbrini, MD, PhD (844-877-4473, MBX4291.Clinicaltrials@mbxbio.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
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.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jun 2026.