A PACT made in a London pub could lead to a cheap version of a drug that cures hepatitis C becoming available to millions of the world鈥檚 poorest people.
Around 200 million people worldwide suffer from the fatal liver disease (see Map), but only 30 million receive the expensive interferon-alpha that can cure them. 鈥淥ur aim was to make a cheap, cost-effective version of the same drug so lots more people could benefit,鈥� says Sunil Shaunak of Imperial College London, who set himself and colleague Steve Brocchini of the University of London鈥檚 School of Pharmacy the challenge while having a drink together several years ago.
Now they may have succeeded. Production of their cheap drug is already being ramped up by Indian collaborators, and clinical trials should begin in 2008.
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Shaunak and Brocchini鈥檚 plan was to outmanoeuvre patents held by chemical giants Hoffman-La Roche and Schering Plough on a new interferon drug that actually cures hepatitis C rather than just reducing the amount of virus in patients鈥� blood, as older interferons do. Its secret is that its surface is studded with a bulky molecule called polyethylene glycol (PEG), which makes the drug last longer in the body.
The problem is its price: in the UK, the drug costs the equivalent of 拢7000 per patient per year. Cheaper copies cannot be made, as the idea of adding surface PEG to interferons has been patented.
To get around this problem, Shaunak, Brocchini and their colleagues at Imperial鈥檚 Hammersmith Hospital site anchored a PEG molecule inside the interferon molecule instead. They did this by gently breaking the disulphide 鈥渂ridges鈥�, bonds that enable a protein it to keep its shape, and relinking them with a three-carbon 鈥渂ridge鈥� attached to a huge PEG molecule (Nature Protocols, vol 1, p 2241).
The drug performed just as well as the PEG-coated versions in human cells infected with hepatitis C, and lasted 12 times longer in the body than interferon without PEG when it was injected into mice.
The approach could also be adapted to increase the 鈥渉alf-life鈥� of drugs for other conditions such as HIV, Shaunak says.
