How does Gleevec work?
In chronic myeloid leukemia, we know that the leukemia cells, the growth of the white blood cells, is driven by a particular enzyme called the “tyrosine kinase.” We know that this family of enzymes regulates cell growth. It’s sort of like the on or off switch for a light. This is the on switch that triggers cells to grow. In the case of chronic myeloid leukemia, there is an abnormality in the chromosomes. Two chromosomes have broken and rearranged and stuck this kinase in the “on” position so it’s always signaling the white blood cells to grow and divide. A normal white count would be 5,000 or 10,000; in a chronic myeloid leukemia patient [the count is] 50,000 to 500,000, so 5 to 50 times the upper limit of normal. What Gleevec does is bind to this specific enzyme and turn it off. It just completely shuts it down, and in fact because of the way that this enzyme works, the cells stop growing and then ultimately die. How does this represent a new way of treating cancer? Up until now the
