RHB-104 is RedHill Biopharma’s drug candidate aimed at treating several inflammatory conditions such as Crohn’s disease, rheumatoid arthritis, and multiple sclerosis (particularly the relapsing-remitting form, RRMS). The drug is an oral capsule with potent intracellular, antimycobacterial, neuroprotective, and anti-inflammatory properties, according to RedHill.
How RHB-104 Works
Chemically, RHB-104 consists of 95 mg of clarithromycin, 45 mg of rifabutin, and 10 mg of clofazimine and is in clinical trials for treating patients with relapsing-remitting multiple sclerosis (Phase 2) and Crohn’s disease (Phase 3). The drug was initially targeted for Crohn’s disease based on evidence the disease is caused by the infection Mycobacterium avium subspecies paratuberculosis (MAP). However, the drug’s neuroprotective properties coupled with its anti-inflammatory qualities support its use in RRMS patients to combat flare-ups and remission.
A second Phase 3 trial, the MAP EU study, is in the planning stage and will be conducted in European countries simultaneously with the MAP U.S. study. Interim analysis of the MAP U.S. trial, with 270 patients, is expected toward the end of 2016, when half of the patients have completed 26 weeks of treatment.
Because bacterially induced dysfunctions of the immune system play an important part in the pathogenesis of multiple sclerosis, scientists were persuaded to undertake clinical development programs to check the drug’s effects on relapsing-remitting MS.
History of RHB-104
After acquiring RHB-104 from Sydney-based Giaconda in August 2010, RedHill put the drug through four different stages of preclinical trials, three of them featuring the murine experimental autoimmune encephalomyelitis MS model. Successful results from these trials paved the way for Phase 1 clinical trials with healthy human hosts to test the safety and toxicity of the drug.
As a result of these reports, RedHill began an 18-patient, Phase 2 proof-of-concept study of RHB-104 as an add-on therapy to Interferon Beta-1a in relapsing-remitting multiple sclerosis (CEASE-MS).
Interim results were recently announced after 24 weeks of treatment. According to RedHill, RHB-104 demonstrated positive safety and clinical signals, and the results support additional clinical development. The drug was found to be safe and well-tolerated in the trial, with no drug-related serious adverse advents.
Final results are consistent with the previous announced interim results, which suggests important safety and clinical signals after 24 weeks of treatment with RHB-104. The treatment effect of RHB-104 appears to be maintained after discontinuing it. Annualized relapse rate (ARR) was 0,288 and 0,29 in the modified intention to treat population (mITT, means that participants were excluded from the analysis if they did not receive a specified minimum amount of the intended intervention), comparing favorably with previous studies of Avonex (0,67) and Rebif (0,87-0,91). Only five relapses were noted during the study, four of which occurred in a single participant. The Expanded Disability Status Scale (EDSS) scores indicate that MS was stable during the study with a slight improvement. The total T2 lesion volume reduced at 24 and 48 weeks, compared to initial volume, and favorably with previous data from Avonex and Rebif. Also there was no clinically significant change for the total number combined unique active lesions during the 24 week treatment, which indicates a stable disease. RHB-104 was safe and well-tolerated without serious or unexpected adverse events.
Earlier this year, Israel-based RedHill Biopharma received a Notice of Allowance from the United States Patent and Trademark Office for its patent covering RHB-104 for Crohn’s disease.
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