The cold virus could help patients undergoing chemotherapy
the cold virus could become a friend for cancer patients. New research suggests that patients undergoing chemotherapy are more likely to survive for a longer period when treated with a cold virus. Fadlo Khuri of the MD Anderson Cancer Center at the University of Texas in Houston, usa, found that three patients with incurable neck and head cancer had survived for three years after being treated with a cold virus modified to attack tumours. They also received simultaneous chemotherapy.
Says Khuri, head of the team that developed the treatment: "All these patients were considered no-hopers beforehand." Usually, patients with head and neck cancer seldom survive between six months to one year when treated with chemotherapy alone. Khuri gave 30 patients cisplatin and 5-fluorouracil -- standard anti-cancer drugs. They also administered a virus that was primed to attack and destroy cancer cells but not healthy ones.
The team chose the virus onyx -015 adenovirus, that normally causes colds. The researchers altered the virus so that it could not replicate in healthy cells, but could infect and destroy cells that have faulty copies of the gene p53 -- the gene that normally destroys abnormal cells before they turn cancerous. Malfunctions in this gene are present in between 45 and 70 per cent of all head and neck cancers, and it is this defect that enables the cancer to grow unchecked.
The virus is ideal for targeting this defect. Normally, the common cold virus destroys p53 in the cells that it infects. This stops the cells self-destructing before the cold virus has had time to make millions of copies of itself. To protect healthy tissue, Khuri deleted E1B -- the gene whose protein would destroy p53 in normal cells -- so onyx -015 would only thrive in cancer cells with defective p53 genes. In trials, the results were impressive. Injected tumours shrank in 19 of the 30 patients. Eleven of the tumours at least halved in size and eight disappeared altogether. Says Khuri: "This is all the more remarkable because the injected tumours averaged 10 centimetres in diameter."
In the next stage of the experiment, Khuri chose 11 patients with multiple tumours. He injected only the largest tumour with the virus and used the smaller tumours as "controls". The virus-treated tumours responded best. Nine of the 11 injected tumours shrank, while only three of the uninjected ones did. Most of the patients subsequently died from tumours that were too inaccessible to inject or from other tumours that grew later. However, out of the 30 patients, three remain disease-free.
Now, Khuri and his collaborators in uk and Canada plan to select 400 patients whose tumours can all be injected with the adenovirus. "If you look at the big picture, these are very impressive results for local control of tumours," says Khuri. "The ultimate question, however, is whether you can translate that into improved survival" ( Nature Medicine , Vol 6, p879).
Meanwhile, another recent piece of research could come as a respite for patients undergoing chemotherapy. One drawback of chemotherapy, hair loss, could be soon be on its way out. Stephen Davis and his colleagues at the Glaxo Wellcome in North Carolina, usa, have found that a drug called gw8510 could help patients keep their hair. In an experiment, the researchers applied the drug to the scalps of rats before treatment with Etoposide, a common chemotherapy. Half the animals suffered no hair loss, and it was significantly reduced in the rest. However, rats that did not receive gw8510 lost most of their hair.
Chemotherapy drugs attack rapidly dividing cells. Unfortunately, they kill not only the fast-growing cancers but also healthy cells that divide rapidly, such as those surrounding the hair follicles. This is why patients undergoing chemotherapy lose their hair. Davis expects that the drug will soon be supplied in a cream or a clear gel that can be applied like shampoo or hair gel ( New Scientist , Vol 166, No 2234).
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