Next-generation leukemia pills, designed to help patients not cured by the successful drug Gleevec, work even better than doctors had hoped, researchers said on Sunday.
One new drug, made by Bristol-Myers Squibb, put 86 percent of patients who tried it into remission — meaning signs of their cancer disappeared, the researchers said.Although they were only Phase I trials, meant to show the drug was safe, the effects were dramatic, the doctors told a meeting in San Diego of the American Society of Hematology.”Certainly it is wonderful. It will save lives,” said Dr. Alan Kinniburgh, senior vice president of research for The Leukemia and Lymphoma Society.Oncologists hope the approach may work in many other cancers, too.Kinniburgh said it is likely that the new pills will be used in combination, like old-fashioned chemotherapy.”I know of no cancer where one single drug has ever cured the cancer,” he said.The new drugs are being tested in patients with chronic myeloid leukemia (CML), which affects about 4,400 Americans a year and 10,000 people around the world.HIGH REMISSION RATEThe Bristol drug is known by its experimental name BMS-354825. During the trial, also financed by Bristol-Myers, 31 of 36 patients with advanced CML, who had not been helped by Gleevec, had a complete hematologic response, meaning their bodies stopped producing leukemia cells.This translates to an 86 percent remission rate, said Dr. Charles Sawyers, a Howard Hughes Medical Institute investigator at the University of California Los Angeles, who is helping test the drug.Gleevec, made by Swiss drug company Novartis, targets an enzyme called BCR-ABL that leukemia cells use to proliferate. It attaches to the cancerous cells and stops them from growing and spreading.Sold in Europe under the name Glivec, it was the first “targeted” cancer drug. It made headlines when it was approved in 2001 because never before had a simple pill shown such dramatic effects in cancer.Gleevec, or imatinib, is Novartis’s second-biggest product, with sales in the first nine months of this year of $1.1 billion.But in a few patients, perhaps 12 percent, the cancer cells mutate just enough to slip out of Gleevec’s grip. The cancer comes back.NEW PILL SEEMS SAFESo some of the researchers who worked on Gleevec teamed with Bristol-Myers Squibb to develop the new pill, which is less picky about how it grabs onto a cancer cell to deactivate it.The Bristol-Myers drug affects a different enzyme called SRC, pronounced “sark.”Sawyers said he and colleagues worried that there could be unforeseen side-effects in patients, as no one had ever tested a SRC inhibitor in people. But so far it seems safe, he said.Novartis also designed its own new compound, AMN107, dubbed “super Glivec,” to overcome the weaknesses in Gleevec. It is in phase I safety tests in 76 patients with advanced leukemia and has shown a strong response in half of them, said Dr. Francis Giles of the M.D Anderson Cancer Center in Houston.”The response rates were dramatic,” Giles said in a telephone interview after presenting his findings to the hematology meeting. Giles and colleagues started patients on very low doses of AMN107, but he believes higher doses will show even better responses.AMN107 is up to 30 times more potent than Gleevec because it was designed to more efficiently bind to the BCR-ABL enzyme, Giles said. “Clearly, we have a decent shot at a cure,” he said.(Source: American Society of Hematology: Reuters Health: Maggie Fox: December 2004.)