New line of defence

A drug which was abandoned because of its toxic effects more than a decade ago is finding new uses in preventing and curing cancer

Published: Friday 15 November 1996

there are already numerous drugs which aid in controlling cancer or even curing it if detected in the early stages. But the drugs, as observed in so many cases, are user specific and their effects vary from person to person depending on factors like the sensitivity of a person, the resistance of a person to infection, the extent of infection and the stage of the disease. Hence, while developing a new drug the foremost consideration is that it should be suitable for the maximum number of people.

About 15 years ago, a lot of work was being done by trying to treat patients with maytansine and its derivatives, a compound developed from certain plants, which acted on bacteria causing cancer of the colon. These were found to be too toxic and hence further work on them was abandoned. Now, the scientists are trying to prevent their side effects.

The method being employed ensures that the compound obtained from the plant directly reaches the site of its action and hence cancer can be cured without toxicity. The drug is being developed by ImmunoGen, a company in Cambridge, Massachusetts, us.

Maytansinoid, the compound under consideration, is known to be 100 to 1000 times more toxic than any other existing drug which cures cancer of the colon. Scientists bound maytansinoid to a mouse antibody and this antibody binds to C 242, which is a glycoprotein and is found near the tumour cells in high levels. In this way the toxic material acts only on the cancerous cells and leaves the healthy ones. Experimental results have proved that this method cures cancer unlike the normally used drug 5-fluorouracil which only delays its process.

The advantage of using potent molecules has been proved after conducting experiments on mice and it will take a couple of years to do the same in human beings. The results seen in this case may not necessarily be the same and as encouraging but they will certainly have an edge over the current drugs used ( New Scientist , Vol 151, No 2045).

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