The FDA has approved pertuzumab (Perjeta), a new anti-HER2 therapy, to treat patients with HER2-positive late-stage breast cancer. Intended for patients who have not received prior treatment for metastatic breast cancer with an anti-HER2 therapy or chemotherapy, pertuzumab is combined with trastuzumab (Herceptin) and docetaxel.
Pertuzumab is a humanized monoclonal antibody that is administered intravenously and is believed to work by targeting a different part of the HER-protein than trastuzumab, resulting in further reduction in growth and survival of HER2-positive breast cancer cells.
Because there are production issues that potentially could affect the long-term supply of the drug, FDA limited its approval to drug product that has not been affected by those issues. Genentech, the manufacturer of pertuzumab, has committed to take steps designed to resolve these production issues in a timely manner.
“Since trastuzumab was first approved more than a decade ago, continued research has allowed us to better understand the role HER2 plays in breast cancer,” said Richard Pazdur, MD, Director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “This research provided the background to combine two targeted drugs—trastuzumab and [pertuzumab] with docetaxel to slow disease progression in breast cancer.”
The safety and effectiveness of pertuzumab were evaluated in a single clinical trial involving 808 patients with HER2-positive metastatic breast cancer who were tested prior to treatment to determine if the HER2 protein was increased. Patients were randomly assigned to receive pertuzumab, trastuzumab, and docetaxel, or trastuzumab and docetaxel with a placebo.
The study was designed to measure progression-free survival. Those treated with the combination containing pertuzumab had a median progression-free survival of 18.5 months, while those treated with the combination containing placebo had a median progression-free survival of 12.4 months.
The most common side effects observed in patients receiving pertuzumab in combination with trastuzumab and docetaxel were diarrhea, hair loss, leukopenia, nausea, fatigue, rash, and peripheral sensory neuropathy.
Pertuzumab is being approved with a Boxed Warning alerting patients and health-care professionals to the potential risk of death or severe effects to a fetus. Pregnancy status must be verified prior to the start of pertuzumab treatment.
The therapy was reviewed under the FDA’s priority review program, which provides for an expedited 6-month review of drugs that may offer major advances in treatment. ■