Promising data from a small Phase 2a clinical trial sponsored by RedHill Biopharma for an antibiotic designed to fight certain infections suggests that adding the drug candidate to interferon treatment reduced relapse rates and brain lesion formation in patients with relapsing forms of multiple sclerosis (MS).
This novel treatment approach was based on studies suggesting that infection caused by the intracellular bacteria Mycobacterium avium subspecies paratuberculosis (MAP) is linked to the development of MS, possibly through MAP-triggered abnormalities of the immune system. The study adds additional support to the theory.
The bacterium, which should not be confused with tuberculosis-causing Mycobacterium tuberculosis, is known to cause disease in animals such as cattle, and has more recently been proposed to cause Crohn’s disease — an inflammatory gut condition.
The proof-of-concept CEASE-MS trial (NCT01717664) was an open-label study in which patients were treated with RedHill’s antibiotic candidate RHB-104 for 24 weeks, as an add-on to interferon beta-1a therapy. Patients were monitored for an additional 24 weeks, during which they returned to interferon beta-1a treatment alone.
The study recruited 18 patients, of which 10 completed the entire trial. Patients had been treated with interferon for an average of five years before entering the study.
The annualized relapse rate was 0.29 during the first 24 weeks, a figure that was maintained throughout the end of the trial at week 48. RedHill, comparing previous trials of interferon beta-1a studies, pointed out that Avonex showed annualized relapse rates ranging from 0.31 to 0.67 in various study groups. Studies of Rebif also showed higher rates, in the 0.39 to 0.91 range.
In addition, the proportion of relapse-free patients compared favorably to previously published interferon data, as 88% were relapse-free during the 24 weeks they received RHB-104, and 93% were relapse-free during the remaining 24 weeks. Previously reported rates for Rebif and Avonex were 75% and 63%, respectively.
RedHill also reported a 3.37% decrease in median brain lesion burden at 24 weeks, which was further decreased to 9.97% at week 48 — again, a better result than that obtained with interferon treatment alone in earlier studies. Disability levels did not worsen during the trial.
“Although designed as an exploratory proof-of-concept study in a very small patient population and not powered for efficacy, the study results demonstrate positive safety data and clinical signals, supporting additional studies to better investigate the therapeutic potential of RHB-104 in RRMS,” Ira Kalfus, MD, medical director of RedHill and the CEASE-MS study, said in a news release.
The treatment was generally well-tolerated, but two participants withdrew from the study because of a metallic taste as well as nausea and vomiting.
As a complement to the proposed treatment with RHB-104, RedHill is developing a companion diagnostic test able to detect MAP infection. The test is being developed for the drug’s use in patients with Crohn’s disease, as the drug has already reached a Phase 3 clinical trial for this condition. RedHill did not comment on the feasibility of the test in MS patients.
The drug candidate was originally developed by Thomas Borody, a professor focusing on drug development in gastrointestinal tract diseases. RedHill acquired RHB-104 from Giaconda in August 2010.