Herceptin is not for every woman with breast cancer. But for the 30 percent whose especially aggressive tumors are fueled by a bad gene called HER2, adding Herceptin can substantially increase the chances of battling the cancer and living a little longer.
Some 50,000 American women a year could benefit from the drug, manufacturer Genentech Inc. estimates.
"For certain women with advanced disease, this new product can mean new hope," said Health and Human Services Secretary Donna Shalala.
The FDA approved Herceptin for advanced breast cancer patients whose HER2-positive tumors have spread to other organs, women who until now have had little hope. They can add it to the drug Taxol as first-line therapy, or use it alone after failing standard chemotherapies.
To make sure the right patients try Herceptin, the FDA also approved a special genetic test kit, HercepTest by Denmark-based Dako Corp., to help doctors measure levels of the bad gene.
Herceptin is a genetically engineered drug that hones in on the gene fueling growth of aggressive cancer.
"The increased used of biological products such as Herceptin to treat the underlying causes of disease is an exciting development in medicine," said FDA Acting Commissioner Michael Friedman, who is a cancer specialist.
The man whose genetic research led to Herceptin considers it an even bigger development: "It heralds a new age in how we're going to treat cancer," said Dr. Dennis Slamon of the Jonsson Cancer Center at the University of California, Los Angeles.
San Francisco-based Genentech said Herceptin would be on pharmacy shelves next month. Women will get weekly intravenous infusions. A price has not been finalized, Genentech said.
Some 30 percent of breast cancer patients have too many copies of a gene called HER2. A healthy version of this gene produces a protein that signals cells to grow and multiply normally. But in women who have too much HER2, the breast cells reproduce out of control and spread through the body.
The drug improved by 16 percent the odds of surviving a full year. Most patients, however, saw about three more months before the cancer progressed, a short respite albeit one considered significant in-patients this sick.
Unlike chemotherapy, Herceptin caused few serious side effects in clinical testing.
But it did pose one serious danger: It sometimes weakens the heart muscle, which can lead to congestive heart failure. The side effect mostly struck patients who took Herceptin together with a type of chemotherapy known as AC, for anthracyclines and cyclophosphamide.
Herceptin should never be used in-patients on AC therapy, the FDA warned, and all Herceptin atients should have their heart function regularly monitored while taking the drug.
Herceptin is the biggest payoff yet in 20 years of basic cancer research into ways to target and fix the many genetic defects that can turn a normal cell into cancer. The National Cancer Institutes estimates that up to 20 other drugs are now in human testing that, like Herceptin, were designed to target these genetic glitches.
The next step is to tell whether Herceptin, approved for advanced breast cancer, works better when given to less sick women, something Slamon is testing. Also under study is whether Herceptin could help certain other cancers where excess HER2 has been discovered.