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September 05, 2012

Virus kills cancer tumors in animals

Telegraph UK = Lab results show a virus is more effective than drugs at killing cancer tumors in animals. However, adenovirus serotype 5 is a common virus in which we have achieved transcriptional targeting by replacing an endogenous viral promoter sequence.

Cheap to produce, the virus is exquisitely precise, with only mild, flu-like side-effects in humans. Photographs in research reports show tumours in test mice melting away.

'It is amazing,' Prof Essand gleams in wonder. 'It's better than anything else. Tumour cell lines that are resistant to every other drug, it kills them in these animals.'

Yet as things stand, Ad5[CgA-E1A-miR122]PTD – to give it the full gush of its most up-to-date scientific name – is never going to be tested to see if it might also save humans. Since 2010 it has been kept in a bedsit-sized mini freezer in a busy lobby outside Prof Essand's office, gathering frost.

A million pounds (1.6 million US dollars) is needed to advance the research




To geneticists, the science makes perfect sense. It is a fact of human biology that healthy cells are programmed to die when they become infected by a virus, because this prevents the virus spreading to other parts of the body. But a cancerous cell is immortal; through its mutations it has somehow managed to turn off the bits of its genetic programme that enforce cell suicide. This means that, if a suitable virus infects a cancer cell, it could continue to replicate inside it uncontrollably, and causes the cell to 'lyse' – or, in non-technical language, tear apart. The progeny viruses then spread to cancer cells nearby and repeat the process. A virus becomes, in effect, a cancer of cancer. In Prof Essand's laboratory studies his virus surges through the bloodstreams of test animals, rupturing cancerous cells with Viking rapacity.

The Uppsala virus isn't unique. Since the 1880s, doctors have known that viral infections can cause dramatic reductions in tumours. In 1890 an Italian clinician discovered that prostitutes with cervical cancer went into remission when they were vaccinated against rabies, and for several years he wandered the Tuscan countryside injecting women with dog saliva. In another, 20th-century, case, a 14-year-old boy with lymphatic leukaemia caught chickenpox: within a few days his grotesquely enlarged liver and spleen had returned to ordinary size; his explosive white blood cell count had shrunk nearly 50-fold, back to normal.

But it wasn't until the 1990s, and the boom in understanding of genetics, that scientists finally learnt how to harness and enhance this effect. Two decades later, the first results are starting to be discussed in cancer journals.

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