The Good News About Cancer
Groundbreaking New Drugs
At the heart of the advances are new targeted therapies, drugs that work at a molecular level to attack the development or functioning of specific types of cancer cells. These include Gleevec (approved by the FDA in 2001 for CML patients) and Herceptin (approved in 1998 for treatment of some metastatic breast cancers), which zero in on parts of the cancer molecule. Avastin, which cuts off cancer's blood supply, won FDA approval in 2004 for some metastatic colorectal cancers, with subsequent approvals for certain forms of lung and breast cancer.
"Targeted drugs are less toxic to normal tissue; they reflect a better understanding of the biology of cancer," says Paul Richardson, MD, clinical director of the Jerome Lipper Center for Multiple Myeloma at the Dana-Farber Cancer Institute, in Boston. Some of these new drugs come in capsules or pill form, so they're easier to take and tolerate than drugs given intravenously. Doctors may use them alone or in combination with more traditional treatments like chemotherapy or radiation.
And these drugs are showing promise with cancers beyond the ones they were designed to treat. Herceptin, for example, which kills HER2-positive breast cancer (tumors that contain a protein called human epidermal growth factor receptor 2), is being tested on HER2-positive stomach tumors. Gleevec is being used to treat GIST as well. "As we better understand the genetic changes that lead to cancer, we'll see cancers treated more according to their genetic makeup rather than the organ where it started," says Allen S. Lichter, MD, CEO of the American Society of Clinical Oncology.
Another new avenue in attacking cancer lies in combining targeted drugs. "The model for the new drugs takes advantage of our understanding of molecular switches that trigger cancer. Maybe if we can turn two switches off at the same time the disease won't come back," says Michael Fisch, PhD, chair of the general oncology department at MD Anderson Cancer Center, in Houston, adding that new delivery systems can take the drugs directly to the tumor. Ellen Rigby, 47, a New York City real-estate attorney, is in her ninth year of treatment for breast cancer that had already spread to her liver at diagnosis. She participated in a clinical trial that attaches a chemo drug to Herceptin. "It's amazing. Herceptin becomes the delivery system that takes the chemo right to the tumor," she says.
In addition to fighting the illness when it first hits, doctors are using some of these drugs in a new way -- as maintenance therapy to keep cancer from returning. One of the first successes was Herceptin; taking it along with chemotherapy after breast-cancer tumor removal reduces the chances the disease will recur by as much as 50 percent, according to Mayo Clinic researchers. Maintenance therapy is controversial, however. Clinical trials are currently gauging how effective newer cancer drugs such as Taxol, Rituxan, and Revlimid are at keeping various cancers at bay.
For patients like Harpham and Garner, the lifesaver was getting into a clinical trial that gave them access to a new drug. For others the benefit is having more lines of treatment to choose from -- another drug to turn to when the effectiveness of the one you're using wanes. Dr. Fisch calls it the hitchhiker method. "Say you're in Houston trying to get to Albuquerque. You're unlikely to find somebody going all the way, so you choose a series of rides that are going in the right direction." Similarly, doctors administer a succession of cancer drugs, riding along with one for as long as it helps, switching to another when necessary.