Gleevec, made by Swiss drug company Novartis AG, is the first drug on the market that employs a new approach to fighting cancer called targeted molecular therapy.
Standard cancer therapy attacks cells that are growing or dividing quickly, including tumor cells and healthy cells found in hair follicles, bone marrow and intestines. This is why patients' hair often falls out, they get anemia and suppressed immune systems and why they experience nausea.
Targeted therapies like Gleevec are designed to go after cancer cells only. As an added benefit, Gleevec and similar drugs coming along can be taken as a pill, as opposed to be infused through a vein.
Gleevec's first big success was in patients with advanced chronic myeloid leukemia, an immune system cancer that will affect 4,400 people in the United States this year and kill 2,000, according to the American Cancer Society.
Dr. Brian Druker of the Oregon Health and Science University and colleagues studied 1,106 early chronic myeloid leukemia patients from 16 countries who received either Gleevec or interferon -- which is given before the disease worsens and a patient undergoes a bone marrow transplant.
Six months later, 54 percent of the Gleevec patients had no signs of the cancer cells in their bone marrow, as opposed to just 3 percent of the interferon patients.
The cancer got worse in 57 percent of patients who received interferon, compared with eight patients who took Gleevec, Druker told the American Society of Clinical Oncology's annual conference in Orlando.
"We were astounded by how much better Gleevec was than standard therapy," Druker told a news conference. "Sixty-eight percent of patients treated with Gleevec had no detectable leukemia, making Gleevec 10 times as powerful as interferon."
"(Chronic myeloid leukemia) is a precursor -- what kills you is an invasive blast crisis," Dr. Charles Balch, the oncology society's executive vice president, said in an interview.
"The cells grow very rapidly, become very bizarre and take over the bone marrow. (Chronic myeloid leukemia) by itself doesn't kill -- the cells are abnormal but they do not crowd out bone marrow cells."
Balch said Gleevec prevented the dreaded blast crisis in many of the patients. "This may be the first cancer that is wiped off the face of the Earth," he said. "We may be able to permanently prevent it."
Gleevec has been approved in a fast-track action by the Food and Drug Administration for use against advanced chronic myeloid leukemia and against gastrointestinal stromal tumor, a relatively rare type of cancer that affects between 2,000 and 5,000 Americans every year.
Stephen McKinnon of University College London warned that no one knows the long-term effects of Gleevec. One potential problem is that some patients who take the drug may not get a bone marrow transplant, now the current standard treatment for CML, which works very well although it is dangerous and traumatic.
Bone marrow transplants work best if done in the first year. Patients who take Gleevec and who later relapse may have blown their chance for a successful bone marrow transplant, he warned. On the other hand, Gleevec may actually make a bone marrow transplant work better -- no one knows.
The other problem is that Gleevec costs $25,000 a year, McKinnon said.