News treatments for rheumatoid arthritis offer hope to patients where existing drugs have failed
Three new treatments for rheumatoid arthritis offer hope to patients where existing drugs have failed.
The new medicines could halt the progress of rheumatoid arthritis (RA), the most common chronic inflammatory joint disease in the industrialised world, affecting up to one per cent of the population. RA is typically associated with swollen, painful joints, but can also cause fever, low red blood cell count, and even lead to premature death if not well treated.
’This opens up a new page with respect to rheumatoid arthritis therapy,’ said Josef Smolen of the Medical University of Vienna, Austria, who has co-authored a review of the new drugs. Smolen spoke to Chemistry World from the European Congress of Rheumatology in Barcelona, where the latest Phase III trial results of the newest RA drug, tocilizumab, will be presented. The other two drugs, rituximab and abatacept, have both already received approval for use.
The three new treatments work by modulating the body’s immune system. RA is an autoimmune disorder; that is, the soft tissues that line the surfaces inside joints are attacked and damaged by the patient’s own immune system. Scientists believe that the initial immune response it triggered by a genuinely infectious organism, but that the resulting antibodies aren’t selective enough to target the infection alone, and so begin to attack the joints. Despite much effort, this theory remains unproven, and the possible identity of the original infection is unknown.
To date, a small molecule drug called methotrexate has proved the single most effective medicine, and is often used in combination with other treatments. But even this combined approach fails in almost half the patients treated.
The new drugs have been licensed to treat patients for whom current therapies fail. Rituximab, approved for treatment of RA in March 2006, has been approved for clinical use for 10 years to treat non-Hodgkinson’s lymphoma. The drug works by targeting and depleting immune response agents called B cells. B cells produce antibodies and act on a group of immune cells called T cells; abatacept works by interfering with T cell activation.
Tocilizumab, meanwhile, targets a proinflammatory molecule called interleukin 6, preventing immune responses from being triggering. Both tocilizumab and abatacept, when combined with methotrexate, relieve 50 per cent of symptoms in over 40 per cent of patients, while rituximab alone is equally effective in more than a third of cases.
’It’s fair to say that the majority of patients with rheumatoid arthritis will, among the spectrum of available drugs, now find agents that not just work, but work well, at treating the disease,’ said Smolen. ’But we’re still a way off from bringing the disease into remission, which has to be the ultimate aim,’ he said.
As with any immunosuppressant drug, side effects of taking these new medicines can be serious. But this must be weighed against the benefit of taking the drug, said Smolen, and the level of side effects are no worse than any other immunosuppressant currently on the market.
James Mitchell Crow
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JS Smolen et alLancet, 2007, DOI:10.1016/S0140-6736(07)60784-3