The viruses that kill tumours

The idea of using viruses to kill cancers goes back nearly a century. In 1912, an Italian gynaecology journal reported the case of a woman with advanced cervical cancer who, after being bitten by a dog, was vaccinated with a live but weakened strain of the rabies virus. To the doctors' surprise, her tumour shrank.

After more reports of patients' tumours regressing after viral infections or vaccinations, doctors began to take the idea seriously. From the late 1940s onwards, several trials took place in which cancer patients were injected with live viruses. A few individuals showed striking improvements, but the results were mixed overall. Doctors pinned their hopes on chemotherapy and radiotherapy instead, and by the end of 1970s the approach had largely been abandoned.
The perfect bioweapon

While viral-therapy papers gathered dust on library shelves, a revolution was under way in biology. Armed with a burgeoning understanding of how viruses infect cells and a battery of techniques for manipulating their genes, researchers realised that they no longer had to rely on the natural tendency of some viruses to home in on cancer cells.

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