Last week's miracle-in-mice may have launched a thousand premature hopes, but there's no doubt in the minds of cancer researchers today that a new era is dawning in the treatment of the U.S.'s No. 2 killer. Three decades ago, the Federal Government's "War on Cancer" underwrote basic discoveries about the ways broken-down genes lead to malignancies. Now that work is beginning to pay off. "The black box that was the cancer cell has been opened," says Dr. Bert Vogelstein, a world-renowned investigator of cancer genes at the Johns Hopkins University in Baltimore, Md. "As researchers, we feel a tremendous amount of hope, probably for the first time in the history of cancer treatment."
In pharmaceutical-company research departments and academic labs around the country, scientists are feverishly at work on drugs that target the products of specific genes--the very genes that make a cell cancerous. The hope is that these treatments will be more effective, longer lasting and far less toxic than traditional chemotherapy and radiation--treatments that inspire dread so deep that they are almost as feared as cancer itself.
"Because of the early success with chemotherapy in some forms of leukemias and lymphomas," says Dr. Dennis Slamon, of the Revlon/UCLA Women's Cancer Research Program, "we have been slugging at cancer that way for 25 years. We didn't make any significant inroads, and in some cases, we ended up killing people. Now we are beginning to look specifically at what's broken in a cancer cell and trying to target that."
What's broken in cancer cells is genes, usually genes that control some aspect of cell growth and division. Hundreds of genes play a role in this process, and more than three dozen have been identified as playing a role in cancer. Some are like accelerators, telling cells to grow, grow, grow. Others put the brakes on growth. Some regulate steps in cell division to make sure that DNA is copied correctly from mother to daughter cell. Some play executioner, killing mutant cells in which the copying has gone awry. Cancer is caused by errors in these genes, usually multiple errors. Though some of these errors may be inherited, most are acquired during years of living. Sunlight, cigarette smoke, environmental toxins and aging itself help these errors accumulate.
Since every gene holds the recipe for a vital protein, corrupt genes mean corrupt proteins: too much of one protein, too little of another, or a misshapen protein that doesn't function properly. The new generation of cancer drugs takes aim at these defective proteins, blocking them, disrupting them in myriad ways. Unlike old-fashioned chemotherapy drugs, the new substances don't poison the tumor--an approach that usually causes collateral damage to healthy cells. Instead, they aim to halt the processes that make a cancer cell act like a cancer cell in the first place.