- Increased PFS seen in patients given pertuzumab plus trastuzumab and docetaxel
- MAb may have different mechanism of action than trastuzumab
The United States Food and Drug Administration (FDA), under its priority review program, recently approved PerjetaTM (pertuzumab), a HER2/neu receptor antagonist indicated in combination with HerceptinR (trastuzumab), another HER2 therapy, and docetaxel for treatment of HER2-positive metastatic breast cancer (BCa) in women who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease.
Perjeta is a humanized monoclonal antibody (MAb) administered intravenously. Experts surmise it works by targeting a part of the HER2 protein other than that targeted by trastuzumab. About 20% of all breast cancers are HER2-positive.
FDA approved the agent in spite of production issues involving cell growth that could affect supply. Genentech (South San Francisco, CA), the manufacturer, is working to resolve the issues and has agreed to post-marketing commitments requested by the FDA involving review of data from the next several productions of the antibody.
Researchers evaluated the safety and effectiveness of Perjeta in a single international Phase III randomized, double-blind, placebo-controlled trial called CLEOPATRA (Clinical evaluation of pertuzumab and trastuzumab). The trial involved 808 women with HER2-positive metastatic BCa. They received either Perjeta,trastuzumab, and docetaxel or trastuzumab, docetaxel, and placebo. The researchers found that those whose treatment included Perjeta had median progression-free survival of 18.5 months versus 12.4 in those whose treatment did not include the agent.
The most common side effects when used with the other 2 agents were diarrhea, hair loss, low white blood cell count, nausea, fatigue, rash, and peripheral neuropathy. Perjeta’s labeling includes a boxed warning alerting patients to risk of death or severe effects to a fetus. Physicians must make sure that women are not pregnant before beginning treatment with the MAb.
Genentech has established a website and toll-free telephone number to provide physicians and patients with information and support. Contact Genentech Access Solutions on their website or 1-888-249-4918.
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