New Leukemia Drugs Help Those Who Fail Gleevec
Sprycel, Tasigna are closing the net on chronic myelogenous leukemia
WEDNESDAY, June 14, 2006 (HealthDay News) -- The prognosis picture for people with chronic myelogenous leukemia (CML) has just gotten even rosier.
Two new studies find that two novel molecular therapies show promise in patients who can't tolerate, or are resistant to, Gleevec.
"Five years ago, the standard of therapy for these patients was transplant. The response was good, but with great cost, and the patients spent the rest of their lives hovering around the hospital," said Dr. Mark H. Kirschbaum, director of new drug development in the division of hematology and hematopoietic cell transplantation at City of Hope, in Duarte, Calif.
"Now you can treat them with a pill," he said.
And because the two new drugs -- Sprycel (dasatinib) and Tasigna (nilotinib) -- work in different ways, they may help an even wider range of patients.
"It's just a very complementary strategy that would, in my mind, argue for using dasatinib in combination with Gleevec or nilotinib as a way to prevent resistance in the future," said Dr. Charles L. Sawyers, senior author of the dasatinib trial and an investigator with the Howard Hughes Medical Institute at UCLA's Jonsson Cancer Center.
Both studies appear in the June 15 issue of the New England Journal of Medicine.
Sprycel could receive U.S. Food and Drug Administration approval in as little as two weeks, Sawyers said. An FDA advisory panel recommended approval earlier this month.
Gleevec's success means that it is now the drug against which all other CML therapies are ranked. Data presented at the recent annual meeting of the American Society of Clinical Oncologists (ASCO) showed that overall five-year survival for people with CML was 89 percent (95 percent if only deaths related to CML were considered). At the same time, 93 percent of patients taking the drug had still not progressed from the chronic to the acute phase of the illness.
But not all the findings were so positive. While the relapse rate for Gleevec in newly diagnosed patients taking it as front-line therapy is low -- about 4 percent per year -- patients who started on a different drug before getting Gleevec tend to relapse earlier, the researchers found.
"Gleevec is great, there's no question," Sawyers said, but not everyone will benefit indefinitely. "There is a reason to have a second drug, and the second drug [Sprycel] looks good."
Another expert agreed.
"Gleevec is doing a fantastic job of taking, but there are still some folks who don't respond or who can't tolerate the drug," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "These drugs begin to fill in these gaps."
Participants in the phase 1 trial of Sprycel had been diagnosed with CML for an average of about eight years, and had already relapsed while on Gleevec. Some were now in the more advanced acute phase of the disease.
All participants were given 15 milligrams to 240 milligrams of Sprycel a day in four-week treatment cycles once or twice daily. The drug comes in the form of a pill.
Sprycel produced a good response in 37 of 40 patients with chronic-phase disease, and in 31 of 44 patients in the acute phase.
"We're seeing basically Gleevec-like results," Sawyers said. The study was funded by grants from the Leukemia and Lymphoma Society and the U.S. National Institutes of Health.
There were some side effects with dasatinib therapy, including panniculitis, an inflammation of the fat under the skin. A research letter in the same issue of the journal detailed panniculitis in two patients taking dasatinib.
For the second study, also a phase 1 trial, 119 patients with Gleevec-resistant CML received nilotinib orally at different doses once or twice daily.
The drug appeared to be active against CML and the safety profile was "relatively favorable," the researchers found. The study was funded by drug maker Novartis Pharmaceuticals.
According to experts, nilotinib is like a "super-Gleevec," a variation on the same molecular theme. Sprycel, on the other hand, works in a completely different way.
Between the two of them, many patients who can't take Gleevec are still being helped.
"The net is getting wider," Kirschbaum said. "Now we need a Gleevec for everything."
"This is emblematic of the sort of situation that we're going to be seeing more and more of as we go forward," Lichtenfeld added.
For more on CML, head to the Leukemia and Lymphoma Society.