New use for old drug

01 February 2009


In today's world of exciting - and expensive - new drugs, it seems unlikely that a drug that's over a hundred years old would have anything new to give us.  But now researchers writing in the journal PloS One have shown that clofazimine - an antibiotic drug that was originally designed to treat TB but didn't work, and is now used to treat leprosy - could bring benefits to people with multiple sclerosis and other immune diseases, such as psoriasis and type 1 diabetes.

Structural diagram of clofazimine.Jun Liu and his team at Johns Hopkins University in the US found that clofazimine hits a molecule called the Kv1.3 potassium channel, which is important in controlling the body's immune response.  They made their discovery as part of a massive screen of more than 3,000 existing drugs, to find out if any had unknown new uses.

This new finding is unusual because clofazimine was previously thought to work on bacteria, not human cells.  But the team discovered that it has a big effect on immune cells that not only start but also carry out immune attack.  This is potentially very useful, because in autoimmune diseases like MS, the body's own immune cells mount an attack on important tissues in the body.

The scientists found that clofazimine blocks the Kv1.3 channels, which in turn stops waves of calcium signals being sent within immune cells known as memory T cells. This stops the T cells responding and mounting an immune assault.  The researchers also found that clofazimine could prevent immune rejection of a human skin graft in mice.

Because clofazimine has already been used to treat leprosy, and is relatively safe, it's likely that it will be fast-tracked into clinical trials for autoimmune diseases in the future.


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