RedHill's RHB-204 Shows Comparable Antimicrobial Efficacy to RHB-104 in Crohn's Disease Development
Key Insights
RedHill Biopharma's RHB-204 demonstrated comparable MAP killing efficacy to RHB-104 in vitro testing, achieving similar antimicrobial activity with lower doses of two active ingredients.
The next-generation formulation offers potential for reduced toxicity and side effects while maintaining the therapeutic approach that showed 64% improvement over standard care in Phase 3 trials.
RHB-204's planned Phase 2 study will be the first clinical trial in a specifically defined MAP-positive Crohn's disease (search) patient population, representing a potentially paradigm-changing treatment approach.
RedHill Biopharma announced new in vitro testing results demonstrating that RHB-204, a next-generation optimized formulation of RHB-104, shows comparable Mycobacterium avium subspecies paratuberculosis (search) (MAP) killing efficacy to its predecessor. The findings represent a significant milestone in developing a potentially transformative oral therapy for Crohn's disease (search) that targets the suspected bacterial cause of the condition.
Enhanced Formulation with Improved Safety Profile
The comparability results were achieved in both spot and phage assays across several different MAP strains. Notably, RHB-204 achieved the same MAP killing efficacy with lower doses of two active ingredients compared to RHB-104, indicating potential for reduced toxicity and side effects.
"The demonstration of RHB-204's comparability to RHB-104 is an important step forward in the ongoing development of RHB-204 for MAP-related CD, following the pathway to approval guided by the FDA at our positive meeting," said Reza Fathi, PhD, Senior VP, R&D at RedHill.
RHB-204 is a proprietary, fixed-dose oral capsule containing clarithromycin, rifabutin and clofazimine at specific doses designed to treat MAP-positive Crohn's disease (search). The optimized dosing profile provides potential for enhanced tolerability, safety and compliance with a 40% pill burden reduction compared to RHB-104.
Strong Clinical Foundation from Phase 3 Success
The development of RHB-204 builds upon robust clinical data from RHB-104's randomized, double-blind, placebo-controlled Phase 3 study in 331 patients with active Crohn's disease (search). The study successfully met its primary and secondary endpoints, showing RHB-104 plus standard of care to be 64% more effective than standard of care alone, achieving clinical remission at week 26 in 36.7% of the RHB-104-treated group compared to 22.4% in the placebo group (p = 0.0048).
The Phase 3 study also demonstrated safety and efficacy of concomitant use with anti-TNFs, immunomodulators and steroids, suggesting RHB-204 could serve as either a stand-alone or combination oral therapy.
Addressing Unmet Medical Need
Current treatment challenges in Crohn's disease (search) highlight the need for new therapeutic approaches. Up to 40% of CD patients fail to respond to anti-TNF (search) treatment, and a similar number of responders lose response over time and experience disease flare-ups. Many existing treatments are expensive, intravenously administered, and carry safety concerns including Black Box Warnings.
"A safe and effective orally administered therapy would provide a welcome alternative approach," Fathi noted.
First-of-Its-Kind Clinical Study Design
RedHill's planned Phase 2 study of RHB-204 is designed to be the first clinical study in a specifically defined MAP-positive CD patient population. This represents a potentially paradigm-changing approach, as previous clinical studies for MAP-directed therapies faced challenges in rapidly and accurately detecting MAP, described as one of the slowest growing and hardest to detect bacteria.
The study design is supported by RedHill's collaborations with two leading European academic centers for cutting-edge MAP detection diagnostics, which could enable both the novel study design and future commercial application of RHB-204.
Regulatory Pathway and Market Opportunity
RHB-204 has received FDA Fast Track and Orphan Drug Designation, along with QIDP Designation under the GAIN Act, extending potential U.S. market exclusivity to 12 years. The drug also received EU Orphan Designation, providing eligibility for 10 years of EU market exclusivity. Patent protection extends through 2041.
RedHill expects to transfer RHB-104's FDA pediatric orphan drug designation to RHB-204 and is exploring additional regulatory designations including breakthrough therapy designation and fast track status.
The Crohn's disease (search) market presents substantial commercial opportunity, with sales in the United States, Japan, and five major European markets expected to grow from $13.6 billion in 2024 to $19.1 billion by 2033, representing a compound annual growth rate of 3.87%.
Disease Background and Current Treatments
Crohn's disease (search) affects an estimated 1 million Americans and approximately 6-8 million people globally. The inflammatory bowel disease (search) causes inflammation of digestive tract tissue, leading to abdominal pain, severe diarrhea, fatigue, weight loss and malnutrition. There is currently no known cure for the condition.
Commonly used FDA-approved therapies include AbbVie (search)'s Humira (adalimumab), Janssen's Remicade (infliximab) and Stelara (ustekinumab), BMS's Zeposia (ozanimod) and Pfizer's Xeljanz (tofacitinib).
RedHill is actively pursuing partnerships and non-dilutive funding sources for the RHB-204 program, including through innovation development grant applications.