Clinical Study to Assess the Efficacy of IMM-124E (Travelan®) in a Controlled Human Infection Model

Up to 60 subjects will be randomized to receive either the Travelan® product or a placebo followed by challenge with ETEC strain H10407. Subjects will receive Travelan® or placebo caplets beginning 2 days prior to experimental challenge with ETEC strain H10407. Travelan®/placebo will be administered for a total of 7 days, or until antibiotic treatment has been initiated. Antibiotic treatment will be initiated after early antibiotic treatment criteria are met or 5 days after challenge.

Early antibiotic treatment will commence when any of the following criteria are met and a physician determines it to be warranted:

1. Severe diarrhea based on volume (800 g in 24 hours) 2. Diarrhea of any severity AND 2 or more of the following symptoms: severe abdominal pain, severe abdominal cramps, severe nausea, severe headache, severe myalgias, severe arthralgia), any fever (≥ 38.0°C), or any vomiting 3. Any fever ≥ 39.0°C 4. Subjects who experience unexpectedly severe events such as symptomatic hypotension (disproportionate to volume loss), renal dysfunction, or altered mental state at the discretion of the investigators. 5. A study physician determines that early treatment is warranted for other reasons.

The placebo is a commercially-sourced high-protein milk product repackaged and masked to mirror the Travelan® product.

Upon admission to the inpatient unit, clinical monitoring will consist of daily medical assessments with adverse event (AE) determination, vital signs at least three times daily, examination and weighing of all stools, stool culture work-up for the challenge strain up to three times daily, and safety laboratory tests. Any subject passing a grade 3-5 stool will be encouraged to start drinking oral fluids at a rate equal to 1.5 times their stool output (or at the same rate as their emesis output as applicable). Intravenous (IV) rehydration will be provided if pre-specified criteria are met.

All subjects will be treated with ciprofloxacin (500 mg by mouth twice daily for three days) or other antibiotic where applicable starting five days after ingesting the H10407 challenge inoculum unless early treatment criteria are met. Subjects will be discharged from the inpatient facility when clinical symptoms are resolved or resolving and two consecutive stool cultures (taken at least 12 hours apart) are negative for the ETEC challenge strain. Subjects may be discharged earlier than Day 8 if they meet criteria.