FDA Approves New Treatment for Advanced Breast Cancer

The US Food and Drug Administration (FDA) today approved Kadcyla (ado-trastuzumab emtansine) for patients with HER2-positive breast cancer that has spread from where it started (metastasized). HER2 is a protein involved in normal cell growth. It is found in increased amounts on some types of cancer cells. In HER2-positive breast cancers, the increased amount of the HER2 protein makes the cancer more aggressive.

Kadcyla is intended for patients who have already tried treatment with trastuzumab, another anti-HER2 therapy, and taxanes, a class of chemotherapy drugs commonly used for the treatment of breast cancer. During clinical research, Kadcyla was referred to as T-DM1.

“Kadcyla is trastuzumab connected to a drug called DM1 that interferes with cancer cell growth,” said Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Kadcyla delivers the drug to the cancer site to shrink the tumor, slow disease progression and prolong survival. It is the fourth approved drug that targets the HER2 protein.”

Kadcyla was evaluated under the FDA’s priority review program, which means the FDA tries to make its decision in only 6 months instead of the usual 10 months.

In a clinical study, 991 patients were randomly assigned to receive either Kadcyla or lapatinib, another drug that blocks HER2, plus chemotherapy. Patients received treatment until either the cancer got worse or the side effects became intolerable. The study was designed to measure progression-free survival, the length of time patients lived without the cancer getting worse, and overall survival, the length of time patients lived before death.

Results showed that patients treated with Kadcyla had an average progression-free survival of 9.6 months compared to 6.4 months in patients treated with lapatinib. Patients in the Kadcyla group also lived an average of 5 months longer than the patients in the lapatinib group.

Kadcyla is being approved with a boxed warning alerting patients and health care professionals that the drug can cause heart damage and liver damage that can be severe enough to cause death. The drug can also cause severe life-threatening birth defects, so it can’t be given to pregnant women. Women should be checked for pregnancy before starting treatment, and women who could become pregnant should use effective contraception while on treatment.

The most common side effects were nausea, fatigue, pain in the muscles or joints, low levels of platelets in the blood, increased levels of liver enzymes, headache, and constipation.

Kadcyla is marketed by Genentech.

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