May 29, 2001 -- As rule, cancer specialists don't like to use words like "cure" and "miracle," but recent developments in cancer research are changing that. When specialists gathered in San Francisco earlier this month for the world's largest cancer research meeting, more than one speaker used the word "miracle" about Gleevec, the new cancer pill approved for leukemia.
Larry Norton, MD, of Memorial Sloan-Kettering Cancer Center in New York puts it this way: "What we now have is a proof of principle that cancer can be cured with medical treatment." And Norton, who is just taking office as president of the American Society of Clinical Oncologists, says that Gleevec represents just the tip of the iceberg.
John Mendelsohn, MD, president of the University of Texas M.D. Anderson Cancer Center in Houston, told a gathering of medical journalists that "there are about a dozen other compounds in the pipeline" that look just as promising as Gleevec, which made headlines with its record-breaking approval by the FDA.
The FDA approved the drug for a specific type of leukemia called chronic myeloid leukemia, or CML. Just days after the FDA announced its decision, Gleevec was grabbing headlines again by demonstrating efficacy in treating a rare type of stomach cancer called gastrointestinal stromal tumor, or GIST. Before Gleevec, there was no effective medical treatment for GIST.
For several decades, cancer specialists have been chasing a way to attack cancer cells directly without also attacking healthy cells in the body, says Norton. The elusive goal has been to find a single pathway that could penetrate the cancer cell and cause it to "commit cell suicide, a process we call apoptosis," says Norton. But for many years the best researchers believed that "cancer cells were so messed up, that it is impossible to correct the problem through a single pathway," he says.
In the last four years, however, researchers have concentrated on drugs that target certain proteins found in cancer cells. Some of these proteins -- like ones found in patients with CML or GIST -- are enzymes in a family called tyrosine kinases, which stimulate cell growth and production. Gleevec homes in on these enzymes and turns them off. Without the signal to grow, the cancer cells die. Healthy cells are left alone.
Working in laboratories, cancer researchers discovered many of these proteins or receptors in the early 1980s, but it has taken all these years to find a way to attack them, says Mendelsohn. "Now, however, I think the pace will pick up, and we can expect to see one or two of these new compounds developed each year for the next decade," he says.
One to two new drugs developing each year for the next 10 years -- what a thrilling prospect.