June 14, 2006 - Two new drugs -- developed with astonishing speed -- offer real hope to patients with deadly forms of.
Chronic myeloid leukemia (CML) is a fatal blood. It can occur when two chromosomes swap genetic material. This swap results in a distorted chromosome -- dubbed the Philadelphia chromosome -- which causes the bone marrow to have deadly, uncontrolled overgrowth of white blood cells. This also causes another fatal cancer: Philadelphia chromosome positive acute lymphoblastic leukemia.
Five years ago, scientists came up with a major breakthrough: Gleevec, the Novartis drug that blocks the action of the abnormal chromosome. But over five years, one in five patients becomes resistant to Gleevec. The result: relapse.
Now, in an unusually rapid payoff from basic science, researchers have come up with two new drugs that work when Gleevec doesn't. One is nilotinib from Novartis, a second-generation offshoot of Gleevec. The other is Sprycel, a new drug from Bristol-Myers Squibb. Novartis and Bristol-Myers Squibb are WebMD sponsors.
Fast Track for Approval
Early clinical trials of nilotinib and Sprycel were supposed to judge only the drugs' safety. But patients did so well in these studies that the drugs are now on the fast track for approval. Results of both studies appear in the June 15 issue of The New England Journal of Medicine. So does an editorial by Brian J. Druker of the Oregon Health and Science University.
The reports "provide immediate hope for patients in whom CML cells have developed resistance to [Gleevec]," Druker writes. "The good news for patients with CML is that the long-term prospects for control of the disease are excellent."
There's more good news. Doctors have found that patients do best when Gleevec has a very powerful initial effect. Both nilotinib and Sprycel are more powerful than Gleevec -- suggesting that patients may do best if started out on one of these new drugs.
Better still, Druker suggests, is if two or three of the drugs could be combined into a superpotent drug cocktail.
There are, however, downsides. Nilotinib appears to cause heart rhythm problems in some patients. And Sprycel causes patients to gather fluid around the outside of the lung. A drug cocktail would work only if it had manageable side effects.
And there's one more problem. There's one mutation to the Philadelphia chromosome that resists all three drugs. Patients with that mutation would still be at risk of fatal leukemia. Even so, Druker says scientists should be up to the task of creating yet another drug to target this triple-resistant mutation.
The Sprycel study included researchers Charles L. Sawyers, MD, of UCLA, and colleagues.
The nilotinib study included researchers Hagop Kantarjian, MD, of Houston's M.D. Anderson Cancer Center, and colleagues.