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Researchers may have developed a powerful new tool
MabThera is the first monoclonal antibody to be licensed for cancer treatment in the UK.
Monoclonal antibodies (MAbs) are obtained from cell clones and target specific antigens - the foreign proteins that trigger an immune response.
Magic bullets
First produced in the 1980s, MAbs were hailed as "magic bullets" because of their ability to selectively target and destroy cancer cells.
However, developing them for use on patients has proved difficult due to problems with production, allergic reactions and clinical effectiveness.
MabThera, the brand name for the drug rituximab, is a treatment for non-Hodgkin's lymphoma (NHL), a cancer of the immune system.
The disease is the seventh most deadly cancer in Britain, killing 4,450 people every year and increasing at a rate of between 3% and 10% a year.
Dr Tony Goldstone, consultant haematologist at University College Hospital, London, said: "MabThera is a significant agent in the treatment of NHL. It is very acceptable to patients, easy to give, and seems to work in some situations where chemotherapy has failed."
Self destruct
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The antibodies work by recognising cancer cells as "foreign" and attaching themselves to them. This both signals the body's own defence mechanisms to attack the tumour and causes the cancer cells themselves to self-destruct.
MabThera is designed to recognise and bind to an antigen called CD20 found only on the surface of B lymphocytes, white cells which form part of the immune system. It is these cells which become cancerous in 70% of NHL cases.
Since the antibody only targets specific cells it avoids many of the side effects of orthodox chemotherapy, such as nausea, hair and weight loss, and fatigue.
MabThera, made by the Roche pharmaceutical company, achieved a 58% response rate in an American study of 166 patients with NHL for whom conventional treatment had failed.