(CBS News) On Friday, The U.S. Food and Drug Administration approved Perjeta (pertuzumab) to treat late-stage breast cancer.
The drug, made by Genentech, significantly delays the time until women with very advanced cases of breast cancer gets worse.
The drug targets cells that make too much of a protein called HER2 - a problem in about one out of four or five breast cancer cases,reported in December. In HER2-positive breast cancers, the increased amount of the protein contributes to cancer cell growth and survival.
The most common side effects of Perjeta were diarrhea, rash, hair loss, fatigue and low white blood cell counts. Among the 402 women given Perjeta in addition to Herceptin and chemotherapy, 69 died - compared with 96 deaths among the 406 women given Herceptin and chemo alone.
Perjeta is being approved with a warning alerting patients and health care providers to the potential risk of death or severe effects to a fetus, saying pregnancy status must be verified prior to the start of treatment.
The FDA said some production issues at Genentech could potentially affect the long-term supply of the drug.
Parent company Roche told WebMD that work is underway to resolve the "cell growth issue" that may affect production.
"We take this very seriously and are working with the FDA to ensure a consistent manufacturing process that maintains drug supply for the people who need it," Dr. Patrick Y. Yang, head of Roche's Pharma Global Technical Operations, said.
"Given the need for additional treatments for metastatic breast cancer, we made the decision to approve this drug today and not to delay its availability to patients pending resolution of the production issues relating to future supply," Dr. Janet Woodcock, director of FDA's Center for Drug Evaluation and Research, said in a written statement. "Genentech is currently developing a plan to mitigate the effect on patients of any potential shortage of Perjeta."
Breast cancer is the second leading cause of cancer-related death among women. This year an estimated 226,870 women will be diagnosed with breast cancer, and 39,510 will die from the disease. About 20 percent of the cases will have increased amounts of HER2 protein.
The American Cancer Society has more on breast cancer.