Pre-Study of Wild Type Enterotoxigenic E. Coli (ETEC) Strain for Verification of a Planned Challenge Dose

NCT06290089 | Completed Results

• 1 other identifier: OEV-131
• Study Type: interventional
• Target: 23
• Locations: 1 country
• Sites: 1

Brief Summary

This was an open-label, single-site pre-study designed to evaluate the safety, tolerability, and infectivity of wild-type Enterotoxigenic Escherichia coli (ETEC) strain E24377A in healthy adults. The aim was to estimate the incidence of moderate and severe diarrhea following oral challenge with approximately 4 × 10⁹ colony forming units (cfu) of the strain. A total of 23 participants were enrolled and monitored in an inpatient setting after receiving a single challenge dose. Clinical signs, symptoms, and stool output were assessed over 120 hours. This challenge model was developed to support a future controlled human infection study (CHIM) evaluating an oral inactivated ETEC vaccine.

Conditions

ETEC Diarrhea

Outcome Measures

Primary Outcomes (2)

• Number of Participants With Moderate and Severe Diarrhea

  Defined as ≥ 4 grade 3-5 stools or \> 400 grams of grade 3-5 stools passed within a rolling 24-hour period, deemed attributable to ETEC

  120 hours post-challenge

• Subjects Developing Moderate-to-Severe Diarrhea Following Oral Challenge

  Each stool was to be graded according to the following scale: Grade 1 = firm, formed Grade 2 = soft but still formed Grade 3 = thick liquid Grade 4 = thin liquid Grade 5 = clear or translucent, watery A loose stool was defined as a Grade 3-5 stool. Diarrhea was defined as passing at least 2 loose (Grade 3-5) stools within a 24-hour period. Diarrhea severity was to be assigned according to the scale in Table 4. Diarrhea Rating Scale: Mild 2-3 Grade 3-5 stools in 24 hours and ≤ 400 grams of Grade 3-5 stools passed in a 24- hour period Moderate 4-5 Grade 3-5 stools in 24 hours or \> 400-800 grams of Grade 3-5 stools passed in a 24-hour period Severe ≥ 6 Grade 3-5 stools in 24 hours or \> 800 grams of Grade 3-5 stools passed in a 24-hours period.

  up to 120 hours post-challenge

Study Arms (1)

ETEC strain

OTHER

Each enrolled subject will receive a single administration of the challenge dose

Other: Enterotoxigenic E. coli (ETEC) strain

Interventions

Enterotoxigenic E. coli (ETEC) strain OTHER

Challenge strain

ETEC strain

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy adults between 18 and 50 years of age, inclusive, at the time of signing the informed consent.
• General good health, without clinically significant medical history, physical examination findings or clinical laboratory abnormalities per clinical judgment of PI.
• Negative pregnancy test at screening and prior to challenge for people of childbearing potential. People of childbearing potential must agree to use an efficacious hormonal or barrier method of birth control during the study. Abstinence is acceptable. People of childbearing potential unable to bear children must have this documented (e.g. tubal ligation or hysterectomy) or must have negative pregnancy tests at screening and prior to challenge.
• Willingness to participate in the study after all aspects of the protocol have been explained and written informed consent obtained.
• Completion of a training session and demonstrated comprehension of the protocol procedures and knowledge of ETEC associated illness by passing a written examination (70% pass score).
• Availability for the study duration, including planned follow-up visit/contact.

You may not qualify if:

• Presence of a significant medical or psychiatric condition which in the opinion of the investigator precludes participation in the study, including gastrointestinal disease (gastritis, irritable bowel disease as suggested by Rome III criteria or medical diagnosis, inflammatory bowel disease). Some medical conditions which are adequately treated and stable would not preclude entry into the study. These conditions might include stable asthma controlled with inhalers or mild hypertension stably controlled.
• Significant abnormalities in screening haematology, or serum chemistry as determined by PI.
• Presence in the serum of HIV antibody, HBsAg, or HCV antibody with confirmation of infection (e.g. by HCV PCR).
• Evidence of IgA deficiency (serum IgA \< 7 mg/dl or limit of detection of assay).
• Evidence of current alcohol or drug dependence.
• Subjects whose Body Mass Index (BMI) is less than 19.0 or greater than 37.0 (kg/m2).
• Recent vaccination or receipt of an investigational product (within 30 days before challenge) or intended vaccination or receipt of investigational products until 60 days after challenge, with the exception of licensed vaccine for influenza or SARS-CoV-2 vaccination that may be given up to 7 days prior to challenge.
• Positive test for SARS-CoV-2 at arrival to the unit on the day of in-patient admission.
• Intention to donate blood or blood products within one month following the completion of study participation (note: The Red Cross will not allow blood donations for 1 year following participation in an investigational research study).
• Any other criteria which, in the investigator's opinion, would compromise the ability of the subject to participate in the study, the safety of the study, or the results of the study.
• Abnormal stool pattern (fewer than 3 per week or more than 3 per day).
• Regular (≥ weekly) use of laxatives, antacids, or other agents to lower stomach acidity.
• Use of any medication known to affect the immune function (e.g., corticosteroids and others) within 30 days preceding the challenge or planned use during the active study period. Use of inhaled or topical steroids may be permitted per PI discretion.
• History of microbiologically confirmed ETEC infection in the last 3 years.
• Occupational handling of ETEC currently, or in the past 3 years.

Sponsors & Collaborators

• Scandinavian Biopharma AB: lead
• Johns Hopkins Bloomberg School of Public Health: collaborator

Study Sites (1)

Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health

Baltimore, Maryland, 21205, United States

Location

Limitations and Caveats

The target enrollment was 30 participants, the data from the 23 enrolled subjects provided sufficient insight into the expected attack rates across diarrhea severity levels.

Results Point of Contact

• Title: Head of Clinical Development
• Organization: Scandinavian Biopharma Holding AB / Etvax

info@scandinavianbiopharma.se

004684705600

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: OTHER
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 26, 2024
• First Posted: March 4, 2024
• Study Start: February 12, 2024
• Primary Completion: February 17, 2024
• Study Completion: September 13, 2024
• Last Updated: July 18, 2025
• Results First Posted: July 16, 2025

Record last verified: 2025-07

Locations

US (1)