A First-in-Patient Study to Evaluate the Safety and Tolerability of HB-2121 as a Diagnostic for Celiac Disease

The goal of this clinical trial is to learn about the safety of a single dose of HB-2121 in adults with suspected celiac disease. It will also look at how the drug affects the small intestine. The main questions it aims to answer are:

• What side effects do participants have after receiving HB-2121?
• How does the drug interact with the small intestine in people with suspected celiac disease?

Researchers will follow participants for 30 days after receiving HB-2121 to understand how the drug behaves in the body and how safe it is.

Participants will:

• Receive one oral dose of HB-2121 four hours before their standard-of-care esophagogastroduodenoscopy
• Attend 4 in-person clinic visits for checkups, lab tests, and monitoring
• Complete 2 remote visits that include safety lab assessments
• Fill out a short daily questionnaire for 7 days about symptoms and health status

Study Overview

• Status: Recruiting
• Conditions: Celiac Disease
• Intervention / Treatment: Drug: HB-2121

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Joaquin Tabera; Phone Number: (650) 334-1308; Email: jtabera7@stanford.edu
• Study Contact Backup: Name: Marissa Dobry; Phone Number: 313-320-2240

Study Locations

• United States
  • California
    • Palo Alto, California, United States, 94304
      • Recruiting
      • Stanford Medicine Clinical and Translational Research Unit (CTRU)
      • Contact: CTRU Director; Phone Number: (650) 497-8168; Email: amrita.herkal@stanford.edu

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age 18 to 75 years
• Undergoing esophagogastroduodenoscopy (EGD) for suspected celiac disease
• Body Mass Index (BMI) between 18 and 45 kg/m2
• Creatinine <1.5 x Upper Limit of the Normal (ULN)
• Total bilirubin ≤ 1.5 mg/dL x (ULN)
• Aspartate aminotransferase (AST)/Serum glutamic oxaloacetic transaminase (SGOT) & Alanine Aminotransferase (ALT)/Serum glutamic pyruvic transaminase (SGPT) ≤ 1.5 x ULN
• Overall good health, as determined by medical history and a physical exam
• No use of an investigational drug within 12 weeks
• Able and willing to follow study procedures and provide written informed consent
• If of childbearing potential, participants must agree to use highly effective birth control during the study period. The same applies to male participants with partners of childbearing potential

Exclusion Criteria:

• Pregnant, breastfeeding, planning to become pregnant, or intending to donate eggs during the study period
• History of cancer or malignancy
• History of chemotherapy and/or pelvic radiation
• History of congenital long QT syndrome or prolonged QTcF interval
• Prisoners, institutionalized individuals, or individuals who are unable to consent for themselves
• Known HIV infection, or positive test for hepatitis B or C, or other clinically significant chronic liver disease
• Current use of immunosuppressant medications
• Known allergy or sensitivity to any ingredients in the study drug
• History of eosinophilic enteritis, Crohn's disease, or ulcerative colitis

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 250 mg HB-2121 in Participants with Suspected Celiac Disease; Participants in this arm will receive a one-time dose of 250 mg of HB-2121.	Drug: HB-2121; HB-2121 taken once orally.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Frequency and severity of adverse events during the study window	Adverse events (AEs) will be recorded and assessed for severity using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0.	From dosing through 30 days post-dose

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intensity of sulfo-Cy5 fluorescent marker normalized to the mean fluorescence intensity of DAPI-stained nuclei in a confocal fluorescent microscopic field of view.	Endoscopic biopsy samples will be collected after dosing, and fresh frozen tissue sections will be stained with DAPI and analyzed using a confocal microscope to determine the fluorescence intensity of sulfo-Cy5 and DAPI.	240 minutes after dosing
Measurement of villous height to crypt depth ratio and intraepithelial lymphocyte count.	Endoscopic biopsy samples will be collected after dosing, and the paraffin-embedded tissue sections will be stained with hematoxylin and eosin, as well as CD3, and analyzed using a microscope to determine villus height, crypt depth, and the number of CD3+ intraepithelial lymphocytes.	240 minutes after dosing

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Frequency and identity of HB-2121 positive cells in the blood of celiac patients	Blood samples will be collected at the end of the overall endoscopic evaluation procedure, and peripheral blood mononuclear cells (PBMCs) will be analyzed using flow cytometry to determine the percentage of HB-2121+ cells among CD14+CD11c+ populations, with and without β7-integrin expression.	Pre-dose and at 360 minutes after dosing
Intensity of of HB-2121-labeled ECM-associated and cellular TG2 protein in duodenal biopsy samples.	Endoscopic biopsy samples will be collected after dosing, and the paraffin-embedded tissue sections will be stained with Collagen 1, PDGFRα, αSMA, CD11c, as well as DAPI, and analyzed using the confocal microscope to determine HB-2121 colocalization with ECM proteins and cell populations.	240 minutes after dosing

Collaborators and Investigators

• Sponsor: Nielsen Fernandez-Becker
• Collaborators: Stanford's Innovative Medicines Accelerator

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: January 9, 2026
• First Submitted That Met QC Criteria: January 21, 2026
• First Posted (Actual): January 30, 2026

Study Record Updates

• Last Update Posted (Actual): April 20, 2026
• Last Update Submitted That Met QC Criteria: April 16, 2026
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Celiac Disease; Esophagogastroduodenoscopy; HB-2121; Gluten Intolerance
• Additional Relevant MeSH Terms: Metabolic Diseases; Intestinal Diseases; Digestive System Diseases; Gastrointestinal Diseases; Malabsorption Syndromes; Nutritional and Metabolic Diseases; Celiac Disease
• Other Study ID Numbers: 84052

Drug and device information, study documents

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