Severe ObesityPhase 2/3GRABS-0NCT06162715
GLP-1 Receptor Agonists Post-Bariatric Surgery (GRABS) Pilot Trial
A Phase 2/3 study testing Tirzepatide in people with Severe Obesity and Obesity, run by Vanderbilt University Medical Center at 1 site in United States.
Trial summary
The goal of this pilot clinical trial is to determine the effectiveness of Tirzepatide in patients with persistent obesity (BMI \> 30) 12 months after bariatric surgery (Roux-en-Y Gastric Bypass). The investigators also aim to determine the frequency of side effects with Tirzepatide in this patient population. Read more about this study
- Who is it for?
- Ages 25 to 65 years
- Conditions the study is for
- Severe Obesity, Obesity, BMI Greater Than 30
- What is being tested?
- Tirzepatide
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteUnited States
- Study dates
- 30 Oct 2024to 1 Dec 2027
- Phase
- Phase 2/3
- 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 25 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Subject must be able to understand and provide informed consent.
- BMI > 30 12 months after bariatric surgery.
- Age > 25 and < 65
- Patients undergoing primary Roux-en-Y Gastric Bypass
Who cannot join
- Inability or unwillingness of a subject to give written informed consent or comply with the study protocol.
- Diagnosis of type I Diabetes
- Revisional bariatric surgery (prior adjustable gastric band, sleeve gastric, vertical banded gastroplasty).
- Use of medications for type 2 di
- Hemoglobin A1c > 8.5 in last 3 months.
- Patient-reported Tobacco, e-cigarette, or smoked marijuana use within 12 months As this would preclude patients from undergoing bariatric surgery.
Show all 21Show fewer
- Personal history of pancreatitis as determined by history.
- Personal or family history of medullary thyroid cancer by history or multiple endocrine neoplasia syndrome type 2
- Pregnancy by urine testing, current lactation, or plans to become pregnant during the study period.
- Use of systemic glucocorticoids in the past 28 days
- Myocardial infarction, unstable angina, stroke, or heart failure (NYHA class II) within 1 year by history.
- History of solid organ transplant.
- History of physician-diagnosed malignancy (other than excised non-melanoma skin cancer) in the past 5 years.
- Current uncontrolled hypertension (systolic >150, diastolic >90) or untreated hyperthyroidism.
- Current, diagnosed, or self-reported drug or alcohol abuse that, in the opinion of the investigator, would interfere with the subject's ability to comply with study requirements.
- Screening creatinine elevation with EGFR < 60 at time of randomization.
- Tobacco use in last 12 months
- Pregnancy
- Prisoners
- Unable or unwilling to follow-up
- Unable to understand English/Spanish
Trial locations and contacts
1 site in 1 country.
United States1 site
Vanderbilt University Medical Center
Nashville, Tennessee, 37209
About this study
The goal of this pilot clinical trial is to determine the effectiveness of Tirzepatide in patients with persistent obesity (BMI \> 30) 12 months after bariatric surgery (Roux-en-Y Gastric Bypass). The investigators also aim to determine the frequency of side effects with Tirzepatide in this patient population. Patients who take tirzepatide 12 months after bariatric surgery will be compared to patients who continue with the current standard of care for patients who have previously undergone Gastric Bypass Surgery.
Read the detailed description
Obesity affects nearly half of the U.S. population, impacting health outcomes including diabetes, cardiovascular risk, longevity, and quality of life. While bariatric surgery such as gastric bypass stands as the most effective intervention, 65% of individuals experience persistent obesity when undergoing surgical weight loss alone. Given the wide-ranging impact of obesity on health outcomes, a critical need exists to explore the efficacy of adjuvant weight loss therapies after gastric bypass surgery. Tirzepatide (TRZ), a type of glucagon-like peptide-1 receptor agonist, shows remarkable effectiveness in medical obesity with 25% weight loss after sustained therapy. However, nearly two-thirds of patients taking medications like TRZ have mild to moderate gastrointestinal (GI) symptoms, including nausea, vomiting, and abdominal pain. These medication side-effects could be a consequence of gastroparesis via vagal stimulation of the stomach, and may represent a major driver of weight loss. Limited data exist regarding use of these newer agents, such as TRZ, in patients who have undergone gastric bypass, which disrupts vagal nerves responsible for managing food transit and gastric emptying. This is a major and timely scientific gap in understanding whether gastric bypass surgery might mitigate these GI symptoms while allowing for enhanced weight loss with adjuvant TRZ use in the post-operative period. The investigators propose a pilot, phase II, open-label trial enrolling patients twelve months after gastric bypass with a nadir Body Mass Index ≥ 30 kg/m2. Study subjects will be randomized to either 24 weeks of TRZ or post-surgery standard of care. Subjects randomized to the standard of care arm will crossover to receive the intervention drug after 24 weeks of observation. Our proposal consists of two aims. First, the investigators will determine the impact of adjuvant TRZ administration on weight, total fat mass, and lean body mass in patients with a history of gastric bypass (Aim 1). Second, the investigators aim to investigate the frequency and severity of GI discomfort associated with TRZ utilizing a validated patient reported outcome questionnaire, and they will investigate the impact of TRZ on GI motility in patients with prior Gastric Bypass (Aim 2).
- Conditions
- Severe Obesity, Obesity, BMI Greater Than 30
- Being tested
- Tirzepatide, Standard of Care post-gastric bypass
- Keywords
- bariatric surgery, Roux-en-Y Gastric Bypass, GLP-1 Receptor Agonists, Tirzepatide, Obesity
- Medical subject headings
- Obesity, Morbid, Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
TirzepatideDrug
Also called Zepbound, Mounjaro
Tirzepatide will be initiated 12 or 18 months (12 months + 24 weeks) after patients undergo Roux-en-Y Gastric Bypass. Patients will be started on the lowest dose of 2.5 mg and the dose increased every 6 weeks following an adaptive maximum dose titration protocol. Patients will then complete a final 4 weeks of the study drug.
Standard of Care post-gastric bypassOther
Patients randomized to the control arm will receive the standard of care for weight maintenance after gastric bypass including dietary guidance provided by the Vanderbilt Surgical Weight Loss handbook. This includes recommendations for 64 oz of fluids per day, ≥60 grams of protein/day, and daily bariatric multivitamins. Patients will continue to have access to dedicated bariatric dietitians, advanced practice providers, and surgeons on an ad hoc basis per patients' request.
| Study group | Role | What they receive |
|---|---|---|
| Tirzepatide Group | Experimental | Participants in the TRZ cohort will initiate a standardized dose titration as described in the package insert. Participants will begin TRZ at 2.5 mg for four weeks and then increase by 2.5 mg every 4 weeks to a maximum dose of 15 mg. If subjects experience intolerable GI symptoms, they will be allowed to decrease to a lower dose by 2.5 mg for 2 weeks, at which point another attempt at an increased dose will be trialed. Should patients not tolerate a higher dose a second time, they will have the dose again lowered by 2.5 mg and kept at the lower dose for the remainder of the study, except for patients who do not tolerate two attempts at 5 mg. For patients who fail to titrate to at least 5 mg TRZ, a third attempt at an increased dose will be attempted 4 weeks after the second decrease in dose. These patients will then remain on 5 mg for the remainder of the intervention period. All participants receiving TRZ will be pooled in terms of outcomes measures. Receives: Drug: Tirzepatide |
| Control - Standard of care Post-Gastric Bypass Surgery | Other | Patients randomized to the control arm will receive the standard of care for weight maintenance after gastric bypass including dietary guidance provided by the Vanderbilt Surgical Weight Loss handbook for 24 weeks. After 24 weeks, particiapnts in the control arm will crossover to the Tirzepatide arm and receive 24 weeks of TRZ following the same titration. Receives: Other: Standard of Care post-gastric bypass |
What is being measured
The primary outcome is the main question the study is designed to answer.
Weight loss
Change in weight over time.
Measured: baseline to 24 weeks
Gastrointestinal symptoms
We will measure the average PAGI SYM score from 0 - 24 weeks in both arms.
Measured: baseline to 24 weeks
Secondary outcomes (3)
Change in body composition
Changes in fat mass
Measured: baseline to 24 weeks
Acetaminophen Area Under the Curve
Changes in acetaminophen area under the curve in the intervention arm
Measured: baseline to 24 weeks
Lean body mass
Utilizing DXA, we will determine changes in lean body mass in both arms
Measured: baseline to 24 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Dec 2023
- Study start30 Oct 2024
- Primary completion1 Jan 2027 (estimated)
- Study completion1 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Severe ObesityStudies of the same condition, open and under way.
- More trials run by Vanderbilt University Medical CenterThe sponsor's other registered studies.
- 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 2/3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Vanderbilt University Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jason Samuels, Vanderbilt University Medical Center
- Investigators
- Jason M Samuels, MD, Principal investigator, Vanderbilt University Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06162715
- Sponsor's protocol ID
- VR72411
- Acronym
- GRABS-0
- Status last verified
- Aug 2026
- First submitted
- 30 Nov 2023
- Last updated
- 4 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: All participant-level data will be preserved and shared. Shared data will be deidentified prior to sharing. Clinicaltrials.gov will document recruitment progress and final results. Study protocols will be shared with publications as supplementary data and made available upon request. All participant consent document will be collected and stored electronically utilizing the REDCap study data repository. The REDCap data warehouse will also contain the study data dictionary. Study protocols have also been published on the ClinicalTrials.gov and any protocol amendments will be reflected on the ClinicalTrials.gov study page. The investigators will utilize the Research Electronic Data Capture (REDCap) data warehouse maintained locally at Vanderbilt for all data collection. Upon study completion and prior to closing the REDCap data warehouse for this study, the investigators will archive all data after removing patient identifiers in the Open Science Framework data repository.
Publications
Samuels JM, Williams CR, Patel MB, Self WH, Funk LM, Roumie C, Spann MD, Northup CJ, Ye F, Irlmeier R, Sohn I, Zhu Y, Niswender K. GLP-1 Receptor Agonists Post-Bariatric Surgery (GRABS) Trial: Rationale, Design and Baseline Characteristics. Diabetes Obes Metab. 2026 Sep 8. doi: 10.1111/dom.71320. Online ahead of print.
PubMed 42712125
Study at a glance
From the registry record, last updated by the sponsor on 4 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- GLP-1 Receptor Agonists Post-Bariatric Surgery (GRABS) Pilot Trial
- ClinicalTrials.gov ID
- NCT06162715
- Acronym / sponsor ID
- GRABS-0 / VR72411
- Conditions
- Severe Obesity, Obesity, BMI Greater Than 30
- Keywords
- bariatric surgery, Roux-en-Y Gastric Bypass, GLP-1 Receptor Agonists, Tirzepatide, Obesity
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Vanderbilt University Medical CenterUniversity, hospital or other
- Study start
- 30 Oct 2024 (actual)
- Primary completion
- 1 Jan 2027 (estimated)
- Study completion
- 1 Dec 2027 (estimated)
- First posted
- 8 Dec 2023 (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 goal of this pilot clinical trial is to determine the effectiveness of Tirzepatide in patients with persistent obesity (BMI \> 30) 12 months after bariatric surgery (Roux-en-Y Gastric Bypass). The investigators also aim to determine the frequency of side effects with Tirzepatide in this patient population. Patients who take tirzepatide 12 months after bariatric surgery will be compared to patients who continue with the current standard of care for patients who have previously undergone Gastric Bypass Surgery.
Detailed description
Obesity affects nearly half of the U.S. population, impacting health outcomes including diabetes, cardiovascular risk, longevity, and quality of life. While bariatric surgery such as gastric bypass stands as the most effective intervention, 65% of individuals experience persistent obesity when undergoing surgical weight loss alone. Given the wide-ranging impact of obesity on health outcomes, a critical need exists to explore the efficacy of adjuvant weight loss therapies after gastric bypass surgery. Tirzepatide (TRZ), a type of glucagon-like peptide-1 receptor agonist, shows remarkable effectiveness in medical obesity with 25% weight loss after sustained therapy. However, nearly two-thirds of patients taking medications like TRZ have mild to moderate gastrointestinal (GI) symptoms, including nausea, vomiting, and abdominal pain. These medication side-effects could be a consequence of gastroparesis via vagal stimulation of the stomach, and may represent a major driver of weight loss. Limited data exist regarding use of these newer agents, such as TRZ, in patients who have undergone gastric bypass, which disrupts vagal nerves responsible for managing food transit and gastric emptying. This is a major and timely scientific gap in understanding whether gastric bypass surgery might mitigate these GI symptoms while allowing for enhanced weight loss with adjuvant TRZ use in the post-operative period. The investigators propose a pilot, phase II, open-label trial enrolling patients twelve months after gastric bypass with a nadir Body Mass Index ≥ 30 kg/m2. Study subjects will be randomized to either 24 weeks of TRZ or post-surgery standard of care. Subjects randomized to the standard of care arm will crossover to receive the intervention drug after 24 weeks of observation. Our proposal consists of two aims. First, the investigators will determine the impact of adjuvant TRZ administration on weight, total fat mass, and lean body mass in patients with a history of gastric bypass (Aim 1). Second, the investigators aim to investigate the frequency and severity of GI discomfort associated with TRZ utilizing a validated patient reported outcome questionnaire, and they will investigate the impact of TRZ on GI motility in patients with prior Gastric Bypass (Aim 2).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Tirzepatide Group | Experimental | Drug: TirzepatideParticipants in the TRZ cohort will initiate a standardized dose titration as described in the package insert. Participants will begin TRZ at 2.5 mg for four weeks and then increase by 2.5 mg every 4 weeks to a maximum dose of 15 mg. If subjects experience intolerable GI symptoms, they will be allowed to decrease to a lower dose by 2.5 mg for 2 weeks, at which point another attempt at an increased dose will be trialed. Should patients not tolerate a higher dose a second time, they will have the dose again lowered by 2.5 mg and kept at the lower dose for the remainder of the study, except for patients who do not tolerate two attempts at 5 mg. For patients who fail to titrate to at least 5 mg TRZ, a third attempt at an increased dose will be attempted 4 weeks after the second decrease in dose. These patients will then remain on 5 mg for the remainder of the intervention period. All participants receiving TRZ will be pooled in terms of outcomes measures. |
| Control - Standard of care Post-Gastric Bypass Surgery | Other | Other: Standard of Care post-gastric bypassPatients randomized to the control arm will receive the standard of care for weight maintenance after gastric bypass including dietary guidance provided by the Vanderbilt Surgical Weight Loss handbook for 24 weeks. After 24 weeks, particiapnts in the control arm will crossover to the Tirzepatide arm and receive 24 weeks of TRZ following the same titration. |
Who may qualify
- Ages
- 25 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Subject must be able to understand and provide informed consent.
- BMI > 30 12 months after bariatric surgery.
- Age > 25 and < 65
- Patients undergoing primary Roux-en-Y Gastric Bypass
Key exclusion criteria (21 listed)
- Inability or unwillingness of a subject to give written informed consent or comply with the study protocol.
- Diagnosis of type I Diabetes
- Revisional bariatric surgery (prior adjustable gastric band, sleeve gastric, vertical banded gastroplasty).
- Use of medications for type 2 di
- Hemoglobin A1c > 8.5 in last 3 months.
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 |
|---|---|---|
| TirzepatideAlso: Zepbound, MounjaroTirzepatide will be initiated 12 or 18 months (12 months + 24 weeks) after patients undergo Roux-en-Y Gastric Bypass. Patients will be started on the lowest dose of 2.5 mg and the dose increased every 6 weeks following an adaptive maximum dose titration protocol. Patients will then complete a final 4 weeks of the study drug. | Drug | Tirzepatide Group |
| Standard of Care post-gastric bypassPatients randomized to the control arm will receive the standard of care for weight maintenance after gastric bypass including dietary guidance provided by the Vanderbilt Surgical Weight Loss handbook. This includes recommendations for 64 oz of fluids per day, ≥60 grams of protein/day, and daily bariatric multivitamins. Patients will continue to have access to dedicated bariatric dietitians, advanced practice providers, and surgeons on an ad hoc basis per patients' request. | Other | Control - Standard of care Post-Gastric Bypass Surgery |
Primary outcome
Weight loss
Time frame: baseline to 24 weeks
Change in weight over time.
Gastrointestinal symptoms
Time frame: baseline to 24 weeks
We will measure the average PAGI SYM score from 0 - 24 weeks in both arms.
3 secondary outcomes
Change in body composition
Time frame: baseline to 24 weeks
Acetaminophen Area Under the Curve
Time frame: baseline to 24 weeks
Lean body mass
Time frame: baseline to 24 weeks
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 4 Aug 2026.
- Derived from this study: PubMed 42712125Samuels JM, Williams CR, Patel MB, Self WH, Funk LM, Roumie C, Spann MD, Northup CJ, Ye F, Irlmeier R, Sohn I, Zhu Y, Niswender K. GLP-1 Receptor Agonists Post-Bariatric Surgery (GRABS) Trial: Rationale, Design and Baseline Characteristics. Diabetes Obes Metab. 2026 Sep 8. doi: 10.1111/dom.71320. Online ahead of print.
- Individual participant dataSharing planned: Yes. All participant-level data will be preserved and shared. Shared data will be deidentified prior to sharing. Clinicaltrials.gov will document recruitment progress and final results. Study protocols will be shared with publications as supplementary data and made available upon request. All participant consent document will be collected and stored electronically utilizing the REDCap study data repository. The REDCap data warehouse will also contain the study data dictionary. Study protocols have also been published on the ClinicalTrials.gov and any protocol amendments will be reflected on the ClinicalTrials.gov study page. The investigators will utilize the Research Electronic Data Capture (REDCap) data warehouse maintained locally at Vanderbilt for all data collection. Upon study completion and prior to closing the REDCap data warehouse for this study, the investigators will archive all data after removing patient identifiers in the Open Science Framework data repository.
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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. This study is not recruiting at the moment.
Jason M Samuels, MD principal investigator
Vanderbilt University Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing Tirzepatide in people with Severe Obesity and Obesity, run by Vanderbilt University Medical Center at 1 site 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 4 inclusion and 21 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: under way, not looking for participants, as of the sponsor's last update on 4 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site 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. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Weight loss (time frame: baseline to 24 weeks). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06162715, which also lists 1 linked publication.
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 4 Aug 2026.