The newly approved “smart bomb” drug, Kadclya, added several months of life to women diagnosed with HER2-positive breast cancer after their tumors had spread following treatment. Although Kadcyla did not cure these women, it did provide them several additional healthy months of life that they otherwise would not have had.
Kadcyla – a member of a new class of drugs called antibody-drug conjugates or ADCs – works by combining the older drug, Herceptin, with the highly toxic chemotherapy drug, DM1, to deliver a more tolerable and better absorbed package of tumor-fighting agents that would otherwise be too harsh on the human body.
“Kadcyla delivers the drug to the cancer site to shrink the tumor, slow disease progression and prolong survival," said Dr. Richard Pazdur, director of the FDA's office of hematology and oncology products.
According to researchers in a report published last year in the New England Journal of Medicine, a trial of 991 women with advanced HER2 breast cancer who received Kadcyla lived an average of 5.8 months longer than those who received more standard chemotherapy, giving them around two-and-a-half years of life after diagnosis versus only two years for those on standard therapy.
Genentech, the company that manufactures Kadcyla, said in a statement that it is now focusing on the ADC formula and hopes it can cause fewer side-effects than ordinary chemo, which can affect healthy tissue.
“We currently have more than 25 antibody-drug conjugates in our pipeline and hope this promising approach will help us deliver more medicines to fight other cancers in the future,” said Dr. Hal Barron, the company’s chief medical officer, in the statement.
Breast cancer remains the number one cancer killer in women. According to the American Cancer Society, approximately 235,000 men and women in the U.S. are diagnosed each year with breast cancer, and 40,000 die from the disease each year. About 20 percent of breast cancer cases are diagnosed as HER2-positive when the tumor cells produce extra amounts of a protein that makes it more resistant to treatments that other breast cancers typically respond to.
The National Cancer Institute says that newly diagnosed women with HER2 breast cancer should still be treated initially for one year with Herceptin alone, but doctors may test the new drug in some volunteers to see if it works better.