If you have terminal liver cancer, a genetically-engineered virus could extend your life. This is according to researchers who carried out a small clinical trial to that effect, who found that the partially disabled cowpox virus helped to prolong the lives of terminally ill liver cancer patients.
For the study, the virus, known as Pexa-Vec or JX-594, was given to 30 patients with advanced liver cancer. JX-594 has been genetically engineered from the vaccinia virus, which has been used as a vaccine for decades and as a tool to eradicate smallpox. It works by multiplying in and subsequently destroying cancer cells, while at the same time mobilising your immune system’s defence against the cancer.
The vaccine was given to 16 patients in high doses, and 14 cancer sufferers in low doses and, according to the findings published in Nature Medicine, those who were given a high dose of the vaccine survived for an average of 14.1 months. Those in the latter group, in comparison, survived for 6.7 months. If patients had a type of advanced liver cancer called hepatocellular carcinoma, the researchers found that they had both a reduction in the size of their tumour and a decreased tumour blood flow, regardless of whether they were treated with a low or high dose. Also irrespective of doses, all of the patients experienced the relatively mild side effect of a day or two of flu-like symptoms, while one patient had severe nausea and vomiting.
According to study co-author Dr David Kirn, a researcher at Jennerex Biotherapeutics in San Francisco, ‘For the first time in medical history we have shown that a genetically engineered virus can improve survival of cancer patients.’ Though these results will need confirming in larger studies, Cancer Research UK has said that they welcome the advance as ‘an exciting step forward’. There is already a 120-patient-large follow-up study being carried out in the US, and the virus is also being tested in other types of cancer.
Professor Alan Melcher, a Cancer Research UK expert at the University of Leeds who is also working on modified viruses to treat cancer, said that the research ‘helps demonstrate the cancer-fighting potential of viruses, which have relatively few side effects in comparison to traditional cancer treatments such as chemotherapy or radiotherapy. If this treatment proves effective in further, larger trials, then it could be available to patients within five years.’
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