Cancer vaccines are showing promise at last

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Subscribe to enjoy similar stories. TOWARDS THE end of the 19th century William Coley, a surgeon in New York, made a surprising observation. One of his patients, close to death with a neck tumour, recovered after catching a serious bacterial skin infection.

Intrigued, Coley tried to replicate the finding, injecting patients with a cocktail of killed bacteria to get their cancers to regress. He ended up treating over a thousand patients in this way, often successfully. Coley’s reasoning was that infection could trigger the immune system to fight cancer.

That idea, controversial during his lifetime, would not become more widely accepted by scientists until the 1950s. Today it is driving efforts to create a new generation of therapies known as “cancer vaccines" that aim to train the immune system to recognise tumours and fight their spread. Trials are now under way against cancers found everywhere from the skin and ovaries to the brain and lungs.

After half a century of disappointing dead ends, promising results are starting to emerge. Cancer can begin from almost any cell in the body. The immune system usually tries to prevent it from spreading by monitoring the body for abnormal cells.

White blood cells known as T-cells, for example, attack tumours by recognising foreign proteins known as non-self antigens on their surfaces. So-called natural killer cells and macrophages can also identify and destroy cancerous cells by searching for the unfamiliar molecules they carry, or after they are tagged by antibodies. If the cells in a cancer evolve to evade the immune system, however, they can then grow, replicate and spread around the body.