06-08-2010 – By TODD ACKERMAN – HOUSTON CHRONICLE
Gleevec was the first big breakthrough drug in targeted cancer therapy, turning a fatal disease into a manageable chronic one, but Houston researchers are reporting that two second-generation leukemia smart drugs are actually far superior.
University of Texas M.D. Anderson Cancer Center scientists released two studies Saturday showing that Tasigna and Sprycel provided chronic myeloid leukemia (CML) patients quicker, better and gentler results as first therapy than the highly touted Gleevec. The two drugs are currently given to patients who become resistant to Gleevec.
“These two studies shows these second-generation targeted therapies have potential as first-line treatment for CML,” said Dr. Hagop Kantarjian, professor and chairman of M.D. Anderson’s department of leukemia. “Either likely would improve outcomes for CML patients.”
The studies were simultaneously presented at the 46th annual meeting of the American Society of Clinical Oncology in Chicago and published online in the New England Journal of Medicine.
Because the studies only followed patients a year — too soon to make definitive claims — Kantarjian stopped short of recommending doctors prescribe Tasigna and Sprycel instead of Gleevec. But in an accompanying journal editorial, a scientist argued the results were so impressive that the difference between the study groups “must be revisited” when longer-term follow-up is available.
A dramatic breakthrough
Gleevec a decade ago introduced the concept of targeted therapy, drugs or other substances that block the growth and spread of cancer by interfering with specific molecules involved in tumor growth and progression. Shutting off such pathways is usually more effective than chemotherapy and radiation and less harmful to healthy cells.
The breakthrough dramatically changed the lives of chronic myeloid leukemia patients, who usually died within a couple years after treatment that made them feel awful. Today, nine years after Gleevec’s approval made headlines around the world, nearly 90 percent of patients are still alive at five years.
But about 30 percent of patients become resistant to Gleevec. They are then switched to Tasigna or Sprycel, which were approved midway through the decade.
The two new studies showed Tasigna and Sprycel work even better among previously untreated patients, a key finding given Kantarjian’s premise that “in cancer therapy it’s important to use your big guns up front.”
The studies enrolled more than 1,350 patients, randomized in one to receive either Tasigna or Gleevec and in the other to receive either Sprycel or Gleevec. All had been recently diagnosed and none had previously been treated.
Few serious side effects
In both cases, the second-generation drugs outperformed Gleevec — more than three-quarters of patients getting Sprycel showed a complete disappearance of the disease-causing chromosome, compared to 66 percent of those getting Gleevec; and an average of 79 percent of patients getting Tasigna showed a complete disappearance of the defective chromosome, compared to 65 percent of those getting Gleevec.
The two second-generation drugs also had more favorable safety profiles, with serious side effects uncommon.
One leukemia expert said he’s not yet ready to change what he prescribes, but praised the study for confirming the promise of targeted therapy, sometimes criticized for not yet living up to all the hype.
“These studies provide additional evidence that targeted therapy works and suggest we can design even better drugs than very effective first-generation ones,” said Dr. Richard Stone, a Harvard Medical School professor and clinical director of the adult leukemia program at the Dana-Farber Cancer Institute in Boston.
todd.ackerman@chron.com
Website: www.chron.com/disp/story.mpl/health/7039824.html