The U.S. Food and Drug Administration recently approved pertuzumab (Perjeta), a new anti-HER2 therapy, for HER2 positive metastatic breast cancer. Pertuzumab may now be used in combination with trastuzumab (Herceptin), an anti-HER2 medicine that targets a different part of the HER2 protein, and docetaxel (Taxotere), a type of chemotherapy.
FDA’s approval comes after results from the CLEOPATRA clinical trial were published in the New England Journal of Medicine in January 2012. The findings showed that women whose tumors were HER2 positive treated with pertuzumab, in combination with trastuzumab and docetaxel, had six more months of progression-free survival than peers treated with trastuzumab and docetaxel alone. Progression-free survival is the length of time after treatment begins that the disease does not grow or worsen.
CLEOPATRA involved 808 women with HER2 positive breast cancer who were randomly assigned treatment with one of two options: trastuzumab, pertuzumab and docetaxel, or trastuzumab, docetaxel, and a placebo (an inactive substance). The women who received treatment with the three active agents (trastuzumab, docetaxel, pertuzumab) had a median of 18.5 months of progression-free survival; their peers treated with only trastuzumab and docetaxel chemotherapy had a median progression-free survival of 12.4 months.
At this time, pertuzumab is approved only for women who have not been treated for metastatic disease with an anti-HER2 therapy or chemotherapy.
In late June, Genentech, the manufacturer of pertuzumab, announced new findings from CLEOPATRA that showed women who received the pertuzumab combination lived longer than those who did not. Those findings have not yet been published in a medical journal. LBBC will report on the full study after its release.
How Pertuzumab Works
Human epidermal growth factor receptor 2, or HER2, proteins are involved in normal cell growth, but in HER2 positive cancers, the quantity of HER2 proteins is much higher than usual.The presence of these excess proteins contributes to the rapid growth of cancer cells.
Anti-HER2 therapies, like pertuzumab and trastuzumab, are medicines that work to block cancer cells’ ability to receive growth signals, which can slow or stop the cells’ growth and the progression of the disease. Both medicines, as well as docetaxel, are given by vein.
Trastuzumab was already proved effective in slowing cell growth, but it targets a different part of the HER protein than pertuzumab. Researchers believe the two medicines together provide a more comprehensive block for growth-signal pathways.
What This Means for You
If you are living with HER2 positive metastatic breast cancer, or were recently diagnosed with metastatic disease, you and your healthcare team may be choosing the treatment plan that best controls the cancer for the longest time. If you have not already been treated with anti-HER2 therapies or chemotherapy for metastatic disease, starting a management plan that includes pertuzumab may lengthen your progression-free survival.
Talk to your doctor about potential treatment options and side effects such as diarrhea, hair loss, decrease in white blood cells, nausea, fatigue, rash and nerve damage (or neuropathy). Consider the differences in side effects should you take trastuzumab and chemotherapy alone, versus taking it with pertuzumab. If you are or believe you may be pregnant,do not take pertuzumab.