Synthetic llama antibodies soothe arthritis pain

Arthritis may have met its match, in the form of the llama immune system. Antibodies similar to ones originally discovered in camels and llamas have helped to heal moderate to severe arthritis in a small trial. The antibodies have inspired the design of a drug, ALX-0061, that blocks a receptor for interleukin 6. This signalling molecule amplifies inflammation, leading to sore and swollen joints. The symptoms ease once the receptor is blocked.

In the trial, 24 patients received one of three unchanging doses of ALX-0061 for six months. Another group received a placebo. Sixty-three per cent of those given the drug saw their symptoms practically vanish. This figure is more than twice the 30 per cent remission rate seen with the current "gold-standard" rival treatment Actemra (tocilizumab). Tocilizumab also targets interleukin 6, but it is based on a normal-sized mammalian antibody.

The remission rate was even higher – 75 per cent – for the eight patients given one of the three doses: 3 milligrams per kilogram of body weight administered once every four weeks. "These data suggest that out of every 10 patients, seven to eight could experience rapid, durable responses to their symptoms," says Josi Holz, the chief medical officer of Ablynx, in Ghent, Belgium, which released its results on 13 February.

According to Ed Moses, CEO of Ablynx, it could be the tiny size of the molecule – one-fifth the usual size – that gives it the edge over existing antibody-based treatments. Other researchers caution against over-optimism because the trial was short and small.