FDA Approves 'Breakthrough' Leukemia Drug
"Certainly, I don't think that anything has been seen like this before," Dawn Willis, PhD, scientific program director of the American Cancer Society, tells WebMD.
From that positive result just two years ago, the FDA went on to grant the drug's manufacturer, Novartis, a priority review. Then in just over two months Gleevec was given accelerated approval, a record time for a cancer drug.
Now Gleevec is being heralded as the first example of so-called "rational drug design" aimed at a targeting the genetic malfunction that exists in CML patients. In these individuals, an abnormal chromosome instructs the body to produce too much of a particular protein, which in turn sends out a message to produce more and more white cells.
In effect, Gleevec has been designed to crank down this biological throttle. "So far, we have evidence from over 1,000 patients that Gleevec reduces that level of cancerous bone marrow and blood ... but it's long-range effect on survival remains to be shown," says FDA Acting Principal Deputy Commissioner Bernard Schwetz, DMV, PhD.
The unknowns are not raining on Gleevec's approval.
"This is a great day for cancer research. For the past 30 years, cancer researchers have tried to identify the critical abnormalities that drive the growth in cancers. ... That approach of understanding cancer at its root can be applied in developing drugs to kill the cancers without harming normal cells -- [that] can now be applied to every single cancer," Drucker tells WebMD.
That, he says, could make cancer treatment as manageable as diabetes, high blood pressure, or elevated cholesterol. However, because every cancer is different, there might have to be hundreds or thousands of targeted molecules against specific tumors.
Nonetheless, some evidence suggests that Gleevec's targeted therapy approach may work in a rare intestinal cancer as well as brain or lung cancers, says Willis.
"What is remarkable about this drug -- its specificity for its molecular target -- also means that its potential utility will be limited to those cancers that have those targets," says Klausner.
Over time, cancer cells also may build up resistance to the specific molecules aimed against them.