A Study to Assess the Efficacy, Safety and Tolerability of AT673 Co-administered With Semaglutide in Adult Participants With Type 2 Diabetes (T2D) and Overweight or Obesity

A Phase 2, Randomized, Double-blind, Placebo-Controlled, Multi-center Study to Assess the Efficacy, Safety and Tolerability of AT673 Co-administered With Semaglutide in Adult Participants With Type 2 Diabetes (T2D) and Overweight or Obesity

The goal of this clinical trial is to learn if AT673 contributes to additional weight loss and glycemic control when given with semaglutide in participants with overweight/obesity and type 2 diabetes. The main questions it aims to answer are:

• To compare the effect on body weight of two doses of AT673 once-weekly versus matched placebo when concurrently administered with semaglutide once-weekly
• To evaluate the effect of AT673 on glycated hemoglobin (HbA1c)
• To compare the safety and tolerability of AT673 versus matched placebo when concurrently administered with semaglutide

Study Overview

• Status: Recruiting
• Conditions: Adults With Overweight/Obesity and Type 2 Diabetes
• Intervention / Treatment: Drug: Placebo; Drug: AT673 low dose; Drug: AT673 high dose

Detailed Description

This is a phase 2, double-blind, placebo-controlled study. Following screening, at their baseline visit, participants will initiate treatment with semaglutide at 0.25 mg/week and follow the product labelled dose escalation schedule until reaching the dose of 1.0 mg/week. Participants will remain on this dose until the end of study (EOS) visit.

At the baseline visit, participants will be randomized in a 1:1:1 ratio to receive AT673 25 mg, or 50 mg, or matching placebo, respectively, once weekly at the same time as semaglutide.

Participants will receive AT673 / placebo injections concurrently with Semaglutide during weekly clinic visits. Treatment with the AT673 / placebo will continue through the end of 13 weeks. This will be followed by a 4-week safety follow-up. The end of study visit will be at week 17.

• Study Type: Interventional
• Enrollment (Estimated): 150
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Arizona
    • Chandler, Arizona, United States, 85224
      • Recruiting
      • CenExel Phoenix
      • Contact: Lee Ann Stapleton Recruitment Specialist; Phone Number: 602-732-6262; Email: l.stapleton@cenexel.com
      • Principal Investigator: Henry Youga, MD
  • California
    • Anaheim, California, United States, 92801
      • Recruiting
      • CenExel Anaheim
      • Contact: Silvia Monico Recruitment Manager; Phone Number: 714-774-7777; Email: s.monico@cenexel.com
      • Principal Investigator: Amina Haggag, MD, FAAFP, CDCES, CPI
  • Florida
    • Hollywood, Florida, United States, 33024
      • Recruiting
      • CenExel Hollywood
      • Principal Investigator: Craig Shapiro, DO, FAOCO
      • Contact: May Fernandez Director of Clinical Operations; Phone Number: 954-990-7649; Email: m.fernandez@cenexel.com
    • Tampa, Florida, United States, 33613
      • Recruiting
      • CenExel Tampa
      • Contact: Beth DeLuca Director of Recruitment; Phone Number: 813-264-2155; Email: e.deluca@cenexel.com
      • Principal Investigator: Deborah White, MD
  • Georgia
    • Atlanta, Georgia, United States, 30331
      • Recruiting
      • CenExel Atlanta
      • Contact: Amber Tannahill Recruitment Manager; Phone Number: 404-881-5800; Email: a.tannahill@cenexel.com
      • Principal Investigator: Elisa Barron, MD
    • Decatur, Georgia, United States, 30030
      • Recruiting
      • CenExel Decatur
      • Principal Investigator: Kimball Johnson, MD
      • Contact: Michael Mahaffey Recruitment Specialist; Phone Number: 404-537-1281; Email: m.mahaffey@cenexel.com
    • Savannah, Georgia, United States, 31405
      • Recruiting
      • CenExel Savannah
      • Contact: Michelle Lagares Recruitment Specialist; Phone Number: 912-744-0800; Email: m.lagares@cenexel.com
      • Principal Investigator: Marilyn Lavalle, MD
  • Utah
    • Salt Lake City, Utah, United States, 84107
      • Recruiting
      • CenExel SLC
      • Contact: Jenny Hunt Recruitment Manager; Phone Number: 801-261-2000; Email: j.hunt@cenexel.com
      • Principal Investigator: Ryan Black, DO

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Signed informed consent prior to start the Screening Visit procedures.
2. Female and male participants ≥18 years of age at time of consent
3. BMI g ≥27.0 kg/m2 at screening.
4. HbA1c ≥7 and ≤10% (53-86 mmol/mol) at screening.
5. Diagnosis of type 2 diabetes mellitus for ≥ 180 days prior to screening.

6. Either treated with diet and exercise alone or on stable (at least 90 days prior to screening) treatment with metformin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, sulfonylurea, and/or DPP4 inhibitor as monotherapy or combination therapy, per approved local label.

   a) Note: Participants treated with sulfonylureas and/or DPP4 inhibitors must discontinue these at least 24 hours prior to initiation of semaglutide.

7. Participant has had at least 1 unsuccessful attempt at weight loss by diet and exercise in the opinion of the investigator.

8. Women of childbearing potential (WOCBP) meeting the criteria below:

   i) Non-lactating and has a negative pregnancy test at screening and baseline -AND- ii) Uses an acceptable method of contraception as determined by the Investigator or Sub-Investigator for the duration of the study and 30 days following the last dose of study drug

9. Participants must, in the opinion of the Investigator, be suitable candidates to receive semaglutide (Wegovy®) as indicated according to the product label.

Exclusion Criteria:

1. Participant has had gastric bypass or other bariatric surgery or endoscopic procedure or any metabolic procedures (e.g. duodenal resurfacing, intragastric balloon, etc.) except for the following:

   1. Liposuction and/or abdominoplasty that was performed > 1 year before screening
   2. Laparoscopic gastric band that was removed > 1 year before screening
   3. Intragastric balloon that was removed > 1 year before screening
   4. Duodenal-jejunal bypass sleeve that was removed > 1 year before screening.
2. Participant has had a self-reported or medically recorded change in body weight > 5% within 3 months of screening OR has recorded change in body weight >3% between screening and randomization.
3. Participant is currently using insulin or used insulin within 3 months before screening.
4. Participant is currently using sulfonylureas and/or DPP4 inhibitors and is unable or unwilling to discontinue the use of these medications at least 24 hours prior to initiation of semaglutide.

5. Participant has a form of diabetes other than type 2.

   a. Note: Previous diagnosis of gestational diabetes is permitted so long as the participant meets all inclusion and none of the exclusion criteria.

6. Participant is currently using or used within 3 months before screening any weight reducing medication including pramlintide, sibutramine, orlistat, zonisamide, topiramate, phentermine, naltrexone, bupropion.
7. Participant is currently using or used within 6 months before screening any medication that contains a GLP-1R agonist component or a GIPR modulator (either by prescription or as part of a clinical study)

8. For participants with a history of prior GLP-1R agonist use (> 6 months prior to screening):

   1. Participant has had a previous intolerance or hypersensitivity to GLP-1 receptor agonists or any of its excipients.
   2. Participant has previously discontinued a GLP-1 receptor agonist after continuous treatment for 6 months or longer due to not meeting personal weight loss goals.
9. Participant is taking any medication that, may cause weight gain unless the participant has used these medications for more than 6 months at a stable dose prior to screening.
10. Participant has hepatic liver enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase levels >2.5, or total bilirubin levels > 1.5 times the upper limit of normal (ULN) at screening.
11. Participant's current alcohol intake exceeds 14 units/week for men or 7 units/week for women (1 unit = half pint of beer, 1 glass of wine, 1 measure of spirits).
12. Participant has a recent history of illicit substance use (< 3 months) or in the opinion of the Investigator suspicion of current illicit substance use.
13. Participant has uncontrolled hypertension at screening (SBP above or equal to 160 mmHg and/or diastolic blood pressure above or equal to 100 mmHg).
14. A corrected QT interval (QTc) of > 450 msec in males or > 470 msec in females at screening, or history of long QT syndrome.
15. Concurrent participation in another interventional study (e.g., of a drug, over the counter product, device) or within ≤90 days or 5 half-lives prior to Screening.
16. Participant is unable to understand and communicate with the investigators; or to understand the protocol requirements, instructions, study-related restrictions, nature, scope, and possible consequences of the clinical study; or is unlikely to comply with the study requirements (e.g., uncooperative attitude and improbability of completing the clinical study).
17. Participant is the investigator or any sub-investigator, research assistant, pharmacist, study coordinator, other staff, or relative thereof directly involved in the conduct of the study, or employee of the sponsor, site, or Contract Research Organization (CRO).
18. Participant whose obesity can be traced to a medical cause, suggestive of genetic or syndromic obesity of an endocrinologic disorder (e.g., hypothyroidism, Cushings syndrome, Prader-Willi syndrome).
19. Participant has a history of an active or untreated malignancy or in remission from a clinically significant malignancy for less than 5 years, except for basal cell carcinoma.
20. Participant has a glomerular filtration rate < 60 mL/min/1.73 m2.
21. Participant has a history of major psychiatric disorders within 5 years or lifetime history of suicide attempt.
22. Participant has any suicidal ideation of type 4 or 5 on the C-SSRS at screening.
23. Participant with a personal or family history of medullary thyroid carcinoma or with multiple endocrine neoplasia (MEN) syndrome type 2.
24. Participant with a previous history of chronic pancreatitis, or acute pancreatitis within 6 months prior to screening.
25. In the opinion of the Investigator, any disorder, condition, inability or unwillingness not covered by the exclusion criteria that may interfere with study procedures, assessments or participant's safety.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low dose; Low dose AT673, subcutaneous injection administered weekly	Drug: AT673 low dose; low dose
Experimental: High dose; High dose AT673 subcutaneous injection administered weekly	Drug: AT673 high dose; high dose
Placebo Comparator: Placebo; matching placebo subcutaneous injection administered weekly	Drug: Placebo; matching placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight	Percent change in body weight from baseline to week 13	13 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
HbA1c	Absolute change from baseline to week 13 in blood concentration of HbA1c (%, mmol/mol)	13 weeks
Safety and Tolerability	Frequency, severity and seriousness of treatment emergent AEs	13 weeks
Achieving clinically significant body weight loss from baseline to week 13	Proportion of participants achieving >5%, and >10% body weight loss from baseline to week 13	week 13
Assess treatment effect on Body Mass Index		13 weeks
Assess the treatment effect on insulin		13 weeks
Assess the treatment effect on blood pressure		13 weeks
Assess the treatment effect on markers of inflammation (hsCRP)		13 weeks
Assess the treatment effect on lipid parameters		13 weeks
Assess treatment effect on waist circumference		13 weeks
Assess the treatment effect on fasting plasma glucose		13 weeks
Assess the treatment effect on HOMA-IR		13 weeks
Assess the treatment effect on heart rate		13 weeks

Collaborators and Investigators

• Sponsor: Antag Therapeutics

Study record dates

Study Major Dates

• Study Start (Actual): June 19, 2026
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: July 14, 2026
• First Submitted That Met QC Criteria: July 20, 2026
• First Posted (Actual): July 24, 2026

Study Record Updates

• Last Update Posted (Actual): July 24, 2026
• Last Update Submitted That Met QC Criteria: July 20, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Glucose Metabolism Disorders; Diabetes Mellitus; Overweight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Obesity; Diabetes Mellitus, Type 2
• Other Study ID Numbers: AT673-OB-200

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No