CHICAGO — Two experimental drugs that fight cancer in novel ways have succeeded in clinical trials, ending lingering doubts about their effectiveness and promising a new era in the treatment of the disease, doctors said here on Sunday.
The two new drugs, products of biotechnology, each attack a particular mechanism by which cancer cells grow. They are far from a cure for cancer. But they promise to extend by months the lives of those who contract it or to shrink tumors, while avoiding some of the serious side effects of conventional chemotherapy. And they open the door to further research that may yield a wave of even more effective drugs operating on similar lines.
"These are new weapons, working in new ways, that allow us to do better," Dr. Mace L. Rothenberg of the Vanderbilt-Ingram Cancer Center in Nashville, Tenn., said at the meeting of the American Society of Clinical Oncology here, where the results were announced.
One of the drugs, Avastin, developed by Genentech, allowed patients with advanced colorectal cancer to live nearly five months longer. The 400 patients who received Avastin in a clinical trial lived a median of 20.3 months, compared with 15.6 months for 400 similar patients receiving chemotherapy alone. Extending life by two to three months makes a new cancer drug successful, so Avastin's five months exceeded expectations. "It is a robust result," said Dr. Richard J. Mayer of the Dana-Farber Cancer Institute in Boston.
The Avastin results are the first significant proof that tumors can be slowed by choking off the blood that brings them oxygen and nutrients, an idea that has been around for 30 years but has met with more failure than success.
The other drug, Erbitux, was developed by ImClone Systems, a company dogged by scandal. Its first application for approval of the drug was rejected in 2001 because the Food and Drug Administration said the company's clinical trials showing the drug's apparent success had been poorly designed and sloppily conducted.
But the results of a more carefully conducted trial unveiled here on Sunday were almost identical to those of the previous study, potentially clearing the way for rapid approval of the drug.
"The first thing to say is, this agent is active," said Dr. David Cunningham of the Royal Marsden Hospital in England, the lead author of the new study.
Both Avastin and Erbitux were tested in patients with colorectal cancer that had spread to other parts of the body. At that point, the cancer is virtually incurable. The new drugs will not change that, but they do promise to lengthen patients' lives.
Colorectal cancer kills 57,000 Americans a year, more than any other cancer except that of the lungs. Until a few years ago, patients found to have advanced colon cancer lived no more than a year. New chemotherapy drugs called irinotecan and oxaliplatin have extended that to a year and a half. Adding Avastin and Erbitux may push it to two years, some doctors said.
"You're talking patients who couldn't make plans for next Thanksgiving, and suddenly they're thinking about their grandson's bar mitzvah which is more than a year away," said Dr. Neal J. Meropol, director of the gastrointestinal cancer program at Fox Chase Cancer Center in Philadelphia.
In the new study, involving 329 patients, Erbitux in combination with irinotecan shrank tumors in 22.9 percent of patients who had exhausted other treatment options. Tumors shrank in 10.8 percent of such patients who got Erbitux alone. The results of the earlier, rejected studies were almost the same: 22.5 percent in combination with irinotecan and 10.5 percent alone.
One goal of the new trial was to show whether combination therapy was better than Erbitux alone. It was not designed to determine whether Erbitux prolongs lives.
The new study was conducted in Europe by Merck of Germany, which has the European rights to Erbitux. Merck said it would apply for approval of the drug soon, and that it could reach the market in 2004. (The company is not related to Merck & Co., the American drug company.)
Executives of ImClone and Bristol-Myers Squibb, which will jointly market the drug in the United States, said they hoped to talk to the FDA soon about whether the new data would be sufficient for approval of the drug in the United States. If so, they could file an application within weeks. If not, they will wait for the results of another clinical trial, expected later this year.
Either way, some analysts said, the drug ought to reach market in the United States by 2004.
For ImClone, which is based in New York, the new results are something of a vindication after 18 months of turmoil that began with the rejection of its first Erbitux application in December 2001. Samuel D. Waksal, the company's founder and chief executive at the time, was later arrested for tipping off relatives to sell ImClone shares before the rejection was announced. His friend Martha Stewart, who also sold ImClone shares at that time, is still under investigation but has not been charged.