In December 2011 results were announced from CLEOPATRA, (CLinical Evaluation Of Pertuzumab And TRAstuzumab) the first randomised Phase III study of the investigational HER2-targeted medicine pertuzumab and published in the New England Journal of Medicine. The study compared the combination of pertuzumab, Herceptin (trastuzumab) and docetaxel chemotherapy to Herceptin and docetaxel alone in people with previously untreated HER2-positive metastatic breast cancer (mBC). People who received pertuzumab in combination with Herceptin and chemotherapy experienced a 38 percent reduction in the risk of their disease worsening or death (progression-free survival, or PFS), (Hazards Ratio=0.62; p-value=<0.0001). The median PFS improved by 6.1 months from 12.4 months for Herceptin and chemotherapy to 18.5 months for pertuzumab, Herceptin and chemotherapy. Overall survival (OS) data are currently immature, with a trend in favour of the pertuzumab combination.
The mechanisms of action of pertuzumab and Herceptin are believed to complement each other as both bind to the HER2 receptor but on different regions. This is believed to provide a more comprehensive blockade of HER signalling pathways

About Pertuzumab

Pertuzumab is a humanized monoclonal antibody being studied in early and advanced stages of HER2-positive breast cancer and advanced HER2-positive gastric cancer. Pertuzumab is unique in that it is designed specifically to prevent the HER2 receptor from pairing with other HER receptors (EGFR/HER1, HER3 and HER4), a process that is believed to play an important role in the growth and formation of several different cancer types. By preventing receptor pairing, pertuzumab is thought to block cell signalling, which may inhibit cancer cell growth or lead to the death of the cancer cell. Binding of pertuzumab to HER2 may also signal the body’s immune system to destroy the cancer cells.

Pertuzumab is not yet available in Australia but clinial trials of it in the adjuvant setting will be commencing at Westmead Hospital in April 2012 for patients with early breast cancer that is Her2 +ve