With the research net being cast widely and deeply by researchers and pharmaceutical companies, it’s clear that the currently approved treatments for rheumatoid arthritis are not having the intended impact on all patients (see this recent post on lack of remission). Unlike some infectious diseases where there is a treatment that often results in a cure (e.g. tuberculosis) or eradication via a vaccine (e.g. polio), no such remedy currently exists for RA. Last year I wrote a post about the large variety of biological treatments for RA that are currently in the development and testing pipeline. And this did not even include the myriad of small molecule drugs being developed to target the so-called JAK-STAT pathways of which Xeljanz (tofacitinib) is the only one currently approved in the United States but not approved in Europe.
The vast majority of approved RA biological treatments focus on inhibiting the tumor necrosis factor (TNF) alpha molecule which is overactive in autoimmune patients. The TNF blockers Enbrel, Remicade, and Humira account for the majority of biological prescriptions and control a vast portion of the market. The newer TNF blockers Simponi and Cimzia have recently joined the fray. Other parts of the involved biological pathways have been targeted for treatment including costimulatory protein CD-40 (Rituxan), interleukin 6 or IL-6 (Actemra), and T cell lymphocytes (Orencia).
In spite of the major focus on TNF alpha, a Belgium company called Ablynx now proposes that over the next few years, the “Anti-IL-6 pathway will dominate as the preferred biologic after anti-TNFα treatment.” They predict that 16% of the RA biological market will consist of IL-6 inhibitors by the year 2021. This focusing on IL-6 signaling pathways was proposed in 2008. In addition to Actemra (tocilizumab) which is currently approved in the U.S. and Europe, other antibody treatments targeting IL-6 are being developed including sarilumab by Sanofi and Regeneron, sirukumab by GlaxoSmithKline, and clazakizumab by Bristol Myers Squibb.
Ablynx is currently completing Phase II clinical trials of an IL-6 inhibitor called ALX-0061 and the results show strong treatment efficacy and safety profiles. Instead of being made of large monoclonal antibody (MAB) molecules like most of the current biological medicines, the company Ablynx focuses on producing smaller components called “nanobodies” or fragments of antibodies (FAB) (see this Scientific American article). FABs are cheaper to produce, may produce fewer side effects, and are less prone to breakdown in harsh environments. Ablynx clones the human FABs in llamas before isolating the molecules (see this report).
It is heartening that much research continues on the development and testing of treatments for RA.