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Introduction |
Cancer is an insidious disease. The culprit is not a foreign invader, but the altered descendants of our own cells , which reproduce uncontrollably. In this civil war, it is hard to distinguish friend from foe, to target the cancer cells without killing the healthy cells. Most of our current cancer therapies, including the cure for childhood leukemia described here, are based on the fact that cancer cells reproduce without some of the safeguards present in normal cells. If we can interfere with cell reproduction, the cancer cells will be hit disproportionately hard and often will not recover.
The scientists and physicians who devised the cure for childhood leukemia pioneered a rational approach to destroying cancer cells, using knowledge about the cell built up from a series of basic research discoveries earlier in this century. That research had shown that the machinery of the cell is based on a large set of chemical reactions that follow one after another like the steps in a production line. These reactions, known as the cell's metabolism, convert food to fat, muscle, and energy--with the starting materials for each step supplied by the previous step. Any one of the many production lines will grind to a halt if one of its steps is faulty. The scientists' approach was to take a chemical that they knew was essential for cell reproduction--a building block for making DNA--and modify it so that it jammed the cell's works when the cell mistook it for the usual chemical. Such deliberately defective materials are called antimetabolites. Many of them are now used as drugs to treat not only cancer, but also gout, bacterial infections, viral infections, and many other illnesses.
The fight against cancer has been more of a war of attrition than a series of spectacular, instantaneous victories, and the research into childhood leukemia over the last 40 years is no exception. But most of the children who are victims of this disease can now be cured, and the drugs that made this possible are the antimetabolite drugs that will be described here. The logic behind those drugs came from a wide array of research that defined the chemical workings of the cell--research done by scientists who could not know that their findings would eventually save the lives of up to thirty thousand children in the United States. |
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