This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.
Introduction: About 20 percent of newly diagnosed breast cancers have high amounts of a protein called HER2 on the surface of the cancer cells (called HER2-positive breast cancer or HER2 over-expression) .
The drugs pertuzumab (Perjeta) and trastuzumab (Herceptin) target HER2-positive cancer cells.
Pertuzumab may be used in combination with trastuzumab and chemotherapy (taxane chemotherapy is preferred) as a first treatment for HER2-positive metastatic breast cancer not treated with pertuzumab in the past. Anthracycline chemotherapy should not be used in this drug combination.
Pertuzumab in combination with trastuzumab and chemotherapy can slow the growth of HER2-positive metastatic breast cancer and increase survival better than trastuzumab and chemotherapy alone .
Learn more about pertuzumab and metastatic breast cancer treatment.
Learn about the side effects of pertuzumab.
Study selection criteria: Randomized clinical trials with 100 or more participants with HER2-positive metastatic breast cancer.
Study Population(number of participants)
Overall Response Rate—Percent who Responded to Treatment(95% CI)
Overall Survival at 1 Year
Phase III clinical trials
CLEOPATRA study [3-5]
Pertuzumab and trastuzumab with chemotherapy (docetaxel)
Trastuzumab with chemotherapy (docetaxel)
PHEREXA study 
Pertuzumab and trastuzumab with chemotherapy (capecitabine)
Trastuzumab with chemotherapy (capecitabine)
CI = Confidence interval
NS = Not statistically significant compared to chemotherapy alone* Estimated survival at 1-year follow-up. Estimated 4-year survival was 58% for the pertuzumab + trastuzumab + docetaxel group and 45% for trastuzumab + docetaxel group. † Estimated survival at 10 months of follow-up.