Travelan® Phase 2 Study Results Published

Immuron aims to develop a military-ready, once-daily formulation for prevention of bacterial diarrhoeal disease.

Rhea-AI Summary

Immuron (IMRN) announced publication of its once-daily Travelan Phase 2 trial results in Scientific Reports, showing mixed efficacy findings. The randomized, placebo-controlled study reported a 50% reduction in ETEC challenge-related adverse events versus placebo (P=0.0001); ETEC is a diarrhoea-causing type of E. coli. Travelan was safe and well tolerated.

The trial did not meet its primary efficacy endpoints. Immuron said the placebo attack rate of 33%, versus 70% anticipated, materially reduced statistical power. Reported reductions were 40% in moderate-to-severe diarrhoea, 50% in severe diarrhoea, 44% in all diarrhoea and 71% in early antibiotic use. The data were previously announced on March 7, 2024.

Immuron has developed a delayed-release capsule for once-daily dosing that may be investigated in larger studies. A manuscript on observed gut microbiome differences is in preparation.

13 points · 0 major

MixediHow this balance works

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1 major · 2 points

Hollow bars mark forward-looking points. How the balance works

Positive

• Moderate pointETEC challenge-related adverse events fell 50% versus placebo, a statistically significant reduction (P=0.0001).
• Minor pointTravelan was safe and well tolerated in the Phase 2 study.
• Minor pointModerate-to-severe diarrhoea showed a reported 40% reduction.
• Minor pointSevere diarrhoea showed a reported 50% reduction.
• Minor pointAll diarrhoea showed a reported 44% reduction.

8 minor points

• Minor pointEarly antibiotic use showed a reported 71% reduction.
• Minor pointMucosal inflammation was attenuated four days post-challenge, with lower fecal myeloperoxidase (p=0.04) and calprotectin (p=0.06) versus placebo.
• Minor pointMore than 80% in both arms developed IgG/IgA anti-ETEC antibodies by day 15–29; Immuron reported no impaired adaptive immunity.
• Minor pointMicrobiome findings included lower relative E. coli abundance, beneficial-bacteria enrichment and greater richness and diversity versus placebo.
• Minor pointPhase 2 results were published in Scientific Reports.
• Minor point. Forward-looking: it has not happened yet and may not happen.Delayed-release capsule developed for once-daily dosing may be investigated in larger, adequately powered studies.
• Minor point. Forward-looking: it has not happened yet and may not happen.Military-ready formulation is Immuron’s development goal for broad-spectrum protection against diarrhoeal pathogens.
• Minor pointCampylobacter jejuni and Shigella sonnei vaccines are progressing with Naval Medical Research Command and Walter Reed Army Institute of Research.

Negative

• Major pointPrimary efficacy endpoints were not met in the once-daily Travelan Phase 2 study.
• Minor pointPlacebo attack rate of 33% versus 70% anticipated materially reduced statistical power, Immuron said.

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Market move: IMRN -5.29% vs previous close. Phase 2 clinical data

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Key Figures

ETEC-related adverse-event reduction: 50% reduction Placebo attack rate: 33% vs 70% Moderate-to-severe diarrhoea reduction: 40% reduction +3 more

ETEC-related adverse-event reduction

50% reduction

Challenge-related adverse events versus placebo; p=0.0001

Placebo attack rate

33% vs 70%

Observed versus anticipated; reduced statistical power

Moderate-to-severe diarrhoea reduction

40% reduction

Travelan study finding

Severe diarrhoea reduction

50% reduction

Travelan study finding

All diarrhoea reduction

44% reduction

Travelan study finding

Early antibiotic use reduction

71% reduction

Travelan study finding

Key Terms

etec, seroconverted, myeloperoxidase, calprotectin

4 terms

etec medical

"ETEC challenge-related adverse events versus placebo"

Enterotoxigenic Escherichia coli (ETEC) is a type of E. coli bacterium that causes diarrheal illness by attaching to the small intestine and releasing toxins that trigger fluid secretion. It spreads by the fecal–oral route, often through contaminated food or water, and is a common cause of traveler's diarrhea and illness in children in low‑resource settings. ETEC is one specific pathotype of E. coli and is distinct from other types that cause disease by different mechanisms.

seroconverted medical

"More than 80% of subjects in both arms seroconverted"

The process by which a person who previously tested negative for specific antibodies develops detectable antibodies in their blood, usually after infection or vaccination; it is identified by a change from a negative to a positive result on a serologic (antibody) test. Seroconversion indicates that the immune system has produced measurable antibodies to a particular pathogen or antigen, but the timing, the antibody types detected, and the level of protection those antibodies provide depend on the illness or vaccine and the specific laboratory assay used.

myeloperoxidase medical

"lower fecal myeloperoxidase (p=0.04)"

Myeloperoxidase is an enzyme released by certain white blood cells during inflammation that helps the body fight infections but can also damage blood vessel walls when present at high levels. Investors watch it because blood tests measuring myeloperoxidase act like a smoke detector for cardiovascular and inflammatory disease risk, influencing demand for diagnostics, drugs, and insurance costs; changes in those markets can affect the value of healthcare and biotech companies.

calprotectin medical

"and calprotectin (p=0.06) than placebo"

A calcium‑ and zinc‑binding protein complex (mainly the S100A8/S100A9 proteins) released by activated neutrophils and monocytes that serves as a marker of acute inflammation; because it is abundant and resistant to bacterial breakdown, it is commonly measured in stool (fecal calprotectin) or blood to detect and monitor neutrophil‑driven inflammation. Fecal calprotectin is used to distinguish inflammatory bowel disease from noninflammatory gut conditions and to track intestinal inflammation over time, while serum calprotectin can indicate systemic inflammatory activity; it is a sensitive marker of inflammation but not specific to a single disease, so elevated levels require clinical correlation and further diagnostic work.

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MELBOURNE, Australia, Oct. 13, 2026 (GLOBE NEWSWIRE) -- Immuron Limited (ASX: IMC; NASDAQ: IMRN) today announced that data from its Phase 2 clinical trial of once-daily oral Travelan^® has been published in the Nature Journal, Scientific Reports.

A copy of the publication can be accessed here: https://doi.org/10.1038/s41598-026-70974-9

The article titled, "A phase 2, randomized, placebo-controlled study to evaluate once-daily oral Travelan for the prevention of Travellers' Diarrhoea," describes clinical data previously announced to the ASX on March 7, 2024.

The clinical study, partially funded by the U.S. Department of Defense (MTEC Award 21010.13), demonstrated that Travelan^® was safe and well tolerated, with a statistically significant 50% reduction in ETEC challenge-related adverse events versus placebo (P=0.0001).

Although the study did not meet its primary efficacy endpoints, a lower than anticipated placebo attack rate (33% versus 70%) materially reduced statistical power. Notwithstanding this limitation, efficacy results consistently trended in favour of Travelan^® across multiple clinically meaningful endpoints, supporting the potential protective benefit of the once-daily formulation against ETEC-associated disease.

Key findings

• Statistically significant 50% reduction in ETEC challenge-related adverse events versus placebo (P=0.0001)
• 40% reduction in moderate-to-severe diarrhoea
• 50% reduction in severe diarrhoea
• 44% reduction in all diarrhoea
• 71% reduction in early antibiotic use
• Travelan recipients showed attenuated mucosal inflammation four days post-challenge, with lower fecal myeloperoxidase (p=0.04) and calprotectin (p=0.06) than placebo
• More than 80% of subjects in both arms seroconverted (IgG/IgA anti-ETEC) by day 15–29, indicating Travelan did not impair natural adaptive immunity to the challenge strain
  
  

A further manuscript describing Travelan's effects on the gut microbiome is currently in preparation. Study data demonstrated that Travelan recipients had lower relative abundance of E. coli, enrichment of beneficial bacteria, and greater microbiome richness and diversity compared with placebo. These observations support the potential for Travelan^® to enhance gut microbiome resilience during pathogenic challenge and antibiotic exposure, representing an additional mechanism by which the product may contribute to gastrointestinal health.

Immuron is advancing Travelan^® as a next-generation, non-antibiotic oral immunoprophylactic for the prevention of bacterial diarrhoeal disease. The program aims to deliver a military-ready, once-daily formulation capable of providing broad-spectrum protection against key pathogens responsible for travellers' diarrhoea and military deployment related gastrointestinal infections.Building on the encouraging findings from the US Government supported clinical study, including a reduction in diarrhea severity and consistently favourable efficacy trends, Immuron has developed a next-generation, delayed-release capsule formulation optimized for once-daily dosing. This novel formulation enables delivery of a substantially higher payload and may be investigated in the larger, adequately powered clinical studies as recommended by the investigators, to further assess its potential to protect against ETEC-associated disease and broader bacterial gastrointestinal infections.

The Naval Medical Research Command and the Walter Reed Army Institute of Research, in collaboration with Immuron, are also progressing the development of novel vaccines targeting Campylobacter jejuni and Shigella sonnei.

Immuron continues to recommend a dose of 1-2 Travelan tablets, three times daily, based on the clinical efficacy observed in previous studies using this regimen, with protection rates of 58.3% (p=0.02), 76.7% (p=0.007) and 90.9% (p=0.0005) (Otto et al., 2011).

This release has been authorised by the directors of Immuron Limited.

COMPANY CONTACT:
Steven Lydeamore
Chief Executive Officer
steve@immuron.com 

About Immuron
Immuron Limited (ASX: IMC, NASDAQ: IMRN), is an Australian biopharmaceutical company focused on developing and commercializing orally delivered targeted polyclonal antibodies for the treatment of infectious diseases.

About Travelan^®
Travelan^® is an orally administered passive immunotherapy that prophylactically reduces the likelihood of contracting travelers’ diarrhea, a digestive tract disorder that is commonly caused by pathogenic bacteria and the toxins they produce. Travelan® is a highly purified tabletized preparation of hyper immune bovine antibodies and other factors, which when taken with meals bind to diarrhea-causing bacteria and prevent colonization and the pathology associated with travelers’ diarrhea. In Australia, Travelan^® is a listed medicine on the Australian Register for Therapeutic Goods (AUST L 106709) and is indicated to reduce the risk of Travelers’ Diarrhea, reduce the risk of minor gastro-intestinal disorders and is antimicrobial. In Canada, Travelan^® is a licensed natural health product (NPN 80046016) and is indicated to reduce the risk of Travelers’ Diarrhea. In the U.S., Travelan® is sold as a dietary supplement for digestive tract protection.

Travelers’ diarrhea (TD)
TD is generally defined as the passage of ≥ 3 unformed stools per 24 hours plus at least one additional symptom (such as nausea, vomiting, abdominal cramps, fever, blood/mucus in the stools, or fecal urgency) that develop while abroad or within 10 days of returning from any resource-limited destinations (Leung et al., 2006). Diarrhea continues to be the most frequent health problem among travelers to destinations in lower- and middle-income regions (Steffen, 2017). Deployed US military personnel, essentially representing a long-term traveller population, are particularly affected given their population dynamics and the context in which they seek care and treatment (Connor et al., 2012). Diarrhea is the leading infectious disease threat to the overall health and preparedness of deployed US armed forces, with diarrheagenic E. coli, Campylobacter spp., and Shigella spp. among the most commonly reported etiologies (Riddle et al., 2006).

Immuron Platform Technology
Immuron’s proprietary technology is based on polyclonal immunoglobulins (IgG) derived from engineered hyper-immune bovine colostrum. Immuron has the capability of producing highly specific immunoglobulins to any enteric pathogen and our products are orally active. Bovine IgG can withstand the acidic environment of the stomach and is resistant to proteolysis by the digestive enzymes found in the Gastrointestinal (GI) tract. Bovine IgG also possesses this unique ability to remain active in the human GI tract delivering its full benefits directly to the bacteria found there. The underlying nature of Immuron’s platform technology enables the development of medicines across a large range of infectious diseases. The platform can be used to block viruses or bacteria at mucosal surfaces such as the Gastrointestinal tract and neutralize the toxins they produce.

IMM-124E (Travelan^®)
IMM-124E was developed using Immuron’s platform technology. IMM-124E is produced from the colostrum of birthing cattle that have been immunised during pregnancy with a vaccine containing the outer antigens of multiple human derived ETEC. A total of 13 ETEC strains are used in the vaccine to produce high levels of antibodies against selected surface antigens from the most common strains of ETEC. (Otto et al., 2011)

The resultant hyperimmune colostrum IMM-124E from ETEC vaccinated cows contains significant levels of polyclonal antibodies specific for ETEC antigens LPS, CFA-I and Flagellin (Sears et al., 2017).

The antibodies produced in IMM-124E have been found to have a stronger binding and neutralizing activity (than the antibodies of unvaccinated cattle) against a wide range of LPS antigens including both the variable O-polysaccharide region and the preserved oligosaccharide core ‘R’ region of LPS from the 13 serotypes used in the ETEC vaccine.

IMM-124E is manufactured into a tablet form referred to as Travelan^®.

References
Connor P, Porter CK, Swierczewski B and Riddle MS. Diarrhea during military deployment: current concepts and future directions. Curr Opin Infect Dis. 25(5): 546-54; 2012.

Hutton, M.L., Cunningham, B.A., Mackin, K.E. et al. Bovine antibodies targeting primary and recurrent Clostridium difficile disease are a potent antibiotic alternative. Sci Rep 7, 3665 (2017). https://doi.org/10.1038/s41598-017-03982-5

Leung AK, Robson WL, Davies HD. Travelers’ diarrhea. Adv Ther. Jul-Aug; 23(4): 519-27; 2006

Otto W, Najnigier B, Stelmasiak T and Robins-Browne RM. Randomized control trials using a tablet formulation of hyperimmune bovine colostrum to prevent diarrhea caused by enterotoxigenic Escherichia coli in volunteers Scandinavian Journal of Gastroenterology 46: 862– 868; 2011.

Riddle MS, Sanders JW, Putnam SD, and Tribble DR. Incidence, etiology, and impact of diarrhea among long-term travelers’ (US military and similar populations): A systematic review. American Journal of Tropical Medicine and Hygiene. 74(5): 891-900; 2006.

Sears KT, Tennant SM, Reymann MK, Simon R, Konstantopolos N, Blackwelder WC, Barry EM and Pasetti MF. Bioactive Immune Components of Anti-Diarrheagenic Enterotoxigenic Escherichia coli Hyperimmune Bovine Colostrum products. Clinical and Vaccine Immunology. 24 (8) 1-14; 2017.

Steffen R. Epidemiology of travelers' diarrhea. J Travel Med. 24(suppl_1): S2-S5; 2017.

For more information visit: https://www.immuron.com.au/ and https://www.travelan.com
Subscribe to Immuron’s InvestorHub: Here

FORWARD-LOOKING STATEMENTS:
This press release may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, each as amended. Such statements include, but are not limited to, any statements relating to our growth strategy and product development programs and any other statements that are not historical facts. Forward-looking statements are based on management’s current expectations and are subject to risks and uncertainties that could negatively affect our business, operating results, financial condition, and stock value. Factors that could cause actual results to differ materially from those currently anticipated include: risks relating to our growth strategy; our ability to obtain, perform under and maintain financing and strategic agreements and relationships; risks relating to the results of research and development activities; risks relating to the timing of starting and completing clinical trials; uncertainties relating to preclinical and clinical testing; our dependence on third-party suppliers; our ability to attract, integrate and retain key personnel; the early stage of products under development; our need for substantial additional funds; government regulation; patent and intellectual property matters; competition; as well as other risks described in our SEC filings. We expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in our expectations or any changes in events, conditions, or circumstances on which any such statement is based, except as required by law.

FAQ

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Did Immuron’s once-daily Travelan Phase 2 trial meet its primary efficacy endpoints?

The trial did not meet its primary efficacy endpoints. Immuron said a lower-than-anticipated placebo attack rate, 33% versus 70%, materially reduced statistical power. The study nevertheless reported a statistically significant 50% reduction in ETEC challenge-related adverse events versus placebo (P=0.0001).

What diarrhoea reductions did Immuron report in the Travelan Phase 2 trial?

Reported reductions were 40% in moderate-to-severe diarrhoea, 50% in severe diarrhoea and 44% in all diarrhoea. Early antibiotic use showed a 71% reduction. These findings did not change the trial’s failure to meet its primary efficacy endpoints.

Does Immuron recommend once-daily Travelan dosing following the Phase 2 results?

Immuron continues to recommend 1–2 Travelan tablets, three times daily, based on efficacy observed in previous studies using that regimen. Those studies reported protection rates of 58.3% (p=0.02), 76.7% (p=0.007) and 90.9% (p=0.0005).