Gleevec Continues to Beat Blood Cancer
89 percent of CML patients have survived for 5 years, study finds
WEDNESDAY, Dec. 6, 2006 (HealthDay News) -- Doug Jenson, a 73-year-old retiree in Canby, Ore., knows what the "wonder drug" Gleevec has given him.
"I've had the pleasure of welcoming a new daughter-in-law, two new granddaughters, seeing my other grandkids grow up. My wife and I just had our 50th anniversary this summer," the former engineer said. "But a few years ago, I didn't think I'd live to see 65."
That's because in 1998, Jenson's doctors called to tell him he had chronic myeloid leukemia (CML) -- at the time, a death sentence.
"Back then, what would happen is that people would take some really tough drugs, interferon or hydroxyurea, and very few -- maybe 2 or 3 percent -- would ever achieve any kind of remission," explained Robin Kornhaber, senior vice president of patient services at the Leukemia and Lymphoma Society.
In fact, Jenson's side effects from interferon were so onerous that he was forced to quit the medication early.
Luckily, his physician mentioned that Dr. Brian Druker, a researcher at the Oregon Health and Science University in nearby Portland, was working on a highly targeted molecular therapy called STI571. The molecule was specifically designed to block the genetic aberration that gives rise to CML, which affects about 6,000 Americans each year.
Jenson signed on to the very first clinical trial for that compound, which was later christened imatinib and then marketed by drug giant Novartis under the name Gleevec.
The result? Like nearly everyone else enrolled in that landmark trial, Jenson has enjoyed continued good health to this day, with almost no side effects.
"Last spring marked my fifth year of undetected CML cells in my blood," Jenson said. "I've been very, very healthy."
The five-year results of the International Randomized Study of Interferon and STI571 (IRIS) trial were first reported in June at the annual meeting of the American Society of Clinical Oncology. They've now made their way to formal publication in the Dec. 7 issue of the New England Journal of Medicine.
In the trial, 1,106 CML patients were randomly chosen to receive either Gleevec or interferon. However, early results were so encouraging that all but 3 percent of those originally placed on interferon switched over to Gleevec.
Five-year overall survival now totals 89 percent -- 95 percent if only deaths linked to CML are considered. By the five-year cutoff, 93 percent of patients had still not progressed from the chronic to the more dangerous acute phase of the illness.
Furthermore, of the 553 patients originally assigned to Gleevec, 96 percent to 98 percent have seen their blood counts return to normal, and 87 percent have experienced a correction in the gene mutation that causes CML.
Side effects were minimal, with 5 percent of patients quitting Gleevec because of drug-related symptoms.
Speaking at the ASCO meeting, Druker said the study "confirms Gleevec as the standard first-line therapy for patients with CML." And, since its first success in treating CML, the drug has also been approved by the U.S. Food and Drug Administration for the treatment of six other rare, life-threatening disorders.
However, "even though all this looks fabulous, they are still not saying this is a cure for CML," the Leukemia and Lymphoma Society's Kornhaber stressed. That's because a sizeable minority of patients don't respond to Gleevec or develop mutations that work around the drug.
But researchers are already ahead of the game there, too. Two new drugs -- Bristol-Myer Squibb's Sprycel (dasatinib) and Novartis' Tasigna (nilotinib) -- "address those problem mutations," Kornhaber said. "They are also 'super-Gleevecs,' in that their potency is much more powerful."
In fact, many researchers believe true long-term suppression of CML will come from a cocktail of these types of drugs, rather than just Gleevec alone.
There has been one cloud in the otherwise sunny outlook for Gleevec, however. In October, the FDA slapped a "precaution" on the drug's labeling after 10 patients developed severe heart failure after taking the medication. A related study, published in July in Nature Medicine, found that Gleevec adversely affects a protein that's important to heart muscle contraction.
Still, the complication appears to be very rare and shouldn't detract from Gleevec's real ability to save lives. "Clearly, the benefits of Gleevec far outweigh the risks," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "What this basically means is that patients have to watch more carefully and be aware of the symptoms."
In the meantime, the success of highly targeted molecular therapies such as Gleevec, Sprycel and Tasigna is giving researchers hope that similar strategies will fight other cancers.
"We're using what we are learning from the way these drugs work on this one leukemia and trying to take some of those lessons to look at the genetics of other leukemias," Kornhaber said.
Jenson agreed that every cancer patient can look to the Gleevec story for inspiration.
"There I was, too -- I had no hope, I thought maybe I'd last three years," he said. Now he works out at the gym each day and feels better than ever.
"In fact, about a year ago, my son looked at me and said, 'Dad, are you sure you had CML?' " Jenson said. "Because that's how good I've been feeling."
For more on CML and other blood cancers, visit the Leukemia and Lymphoma Society.