RedHill Biopharma Ltd. (NASDAQ:RDHL) announced on November 2, 2026, results from two sets of in vitro studies confirming RHB-204's killing capability on Mycobacterium avium subspecies paratuberculosis (MAP) and its comparability to RHB-104's MAP-killing effect in both long-term intracellular culture and spot and phage assays.

Key Highlights

  • Two independent lab studies confirmed RHB-204's MAP-killing capability, led by Professor Tim Bull at City St George's University of London and Prof Irene Grant and Dr Hannah Dane at Queen's University Belfast.
  • RHB-204 showed comparable MAP-killing to RHB-104 across multiple MAP strains from both human Crohn's disease patients and animal carriers of Johne's disease.
  • MAP killing efficacy was achieved with lower doses of two of the active ingredients compared to RHB-104, which the filing describes as "indicative of potential for reduced toxicity and side effects."
  • RHB-204 did not induce tolerance in MAP strains during exposure periods of up to 6 days maximum, according to the filing.
  • RHB-104's Phase 3 trial, referenced as context, showed RHB-104 plus standard of care to be 64% more effective than standard of care alone in treating Crohn's disease versus placebo (p = 0.0048).
  • RHB-204 is patent protected through 2041 and holds FDA Fast Track, Orphan Drug, and QIDP designations, as well as EU Orphan Designation.

RHB-204 In Vitro Results and Implications for Crohn's Disease Development

According to the filing, the first set of studies, led by Professor Tim Bull of City St George's University of London, confirmed RHB-204's MAP-killing capability in long-term intracellular culture across a range of MAP strains drawn from both human Crohn's disease patients and animal carriers of Johne's disease. Professor Bull is quoted in the filing as stating that "RHB-204 demonstrated a significant MAP-killing effect, similar to RHB-104, against multiple strains of MAP, both human and animal, whilst intracellularly persistent." The filing also notes that RHB-204 did not induce tolerance in the strains during the short exposure periods used, with a maximum of 6 days, suggesting that "further consecutive dosing could add to the effect."

The second set of studies, conducted by Rapid-myco Technologies and led by Prof Irene Grant and Dr Hannah Dane of Queen's University Belfast, showed in vitro that RHB-204 demonstrated comparable MAP killing to RHB-104 in both spot and phage assays. The filing notes that MAP killing efficacy was achieved with lower doses of two of the active ingredients compared to RHB-104. RedHill's Senior VP of R&D, Reza Fathi, PhD, is quoted describing RHB-204 as "Phase 2-ready" and stating a belief that it "could be among the first treatments to be evaluated in an adequately controlled study in a specifically defined MAP-positive Crohn's disease patient population."

The filing describes RHB-204 as a proprietary fixed-dose oral capsule containing clarithromycin, rifabutin, and clofazimine, offering a 40% pill burden reduction compared to RHB-104. RedHill disclosed it is "actively pursuing partnerships and collaborations for this program, including through innovation development grant applications." The filing also references a projected Crohn's disease market compound annual growth rate of 3.87%, reaching $19.1 billion by 2033 in the United States, Japan, and five major European markets, citing a third-party source footnoted in the original document.

What Was Disclosed

RedHill Biopharma disclosed the results of two independent in vitro research programs confirming RHB-204's MAP-killing capability and its comparability to RHB-104, providing data the company says supports continued development of RHB-204 for MAP-related Crohn's disease.