Final phase III trial results showed that adding Perjeta to Herceptin and docetaxel chemotherapy increased overall survival to over four-and-a-half years in patients with previously untreated HER2-positive metastatic breast cancer.
Data from the CLEOPATRA study showed that the addition of Perjeta (pertuzumab) increased median overall survival 15.7 months compared to Herceptin (trastuzumab) and docetaxel alone—to 56.5 and 40.8 months, respectively.
The data were presented at the Presidential Symposium at the European Society for Medical Oncology Congress in Madrid.
“Adding Perjeta to treatment with Herceptin and chemotherapy resulted in the longest survival observed to date in a clinical study of people with HER2-positive metastatic breast cancer,” said Sandra Horning, chief medical officer and head of Global Product Development at Genentech, Perjeta’s sponsor.
Perjeta in combination with Herceptin and docetaxel chemotherapy is approved in the U.S. and the European Union for people with previously untreated HER2-positive metastatic breast cancer.
CLEOPATRA was an international, randomized, double-blind, placebo-controlled study. The study evaluated 808 patients with previously untreated HER2-positive MBC, or with HER2-positive MBC that had come back after prior therapy in the adjuvant or neoadjuvant setting. The primary endpoint of the study was progression-free survival.
An interim OS analysis was previously presented at the San Antonio Breast Cancer Symposium in 2012. At the time of the analysis, median OS had not yet been reached for people receiving the Perjeta regimen as more than half of these people continued to survive.
The results presented at the ESMO Congress are from the final pre-specified OS analysis after a median follow-up of 50 months. No new safety signals were observed.
An updated analysis of previously reported CLEOPATRA survival data showed that risk of death was reduced by 32 percent for people who received Perjeta, compared to those who received Herceptin and chemotherapy (HR=0.68, 95% CI 0.56-0.84; p=0.0002); those patients also had a 32 percent reduction in the risk of their disease worsening or death (HR=0.68, 95% CI 0.58-0.80).
With longer follow-up, the median PFS improvement of more than six months was maintained—median PFS of 18.7 months for patients in the Perjeta arm, compared to 12.4 months for those who received Herceptin and chemotherapy.
These data will be submitted to regulatory authorities around the world for inclusion in the prescribing information for Perjeta.
Perjeta is designed to prevent the HER2 receptor from pairing with other HER receptors on the surface of cells, a process that is believed to play a role in tumor growth and survival. Binding of Perjeta to HER2 may also signal the body’s immune system to destroy the cancer cells.
The mechanisms of action of Perjeta and Herceptin are believed to complement each other, as both bind to the HER2 receptor, but to different places. The combination of Perjeta and Herceptin is thought to provide a more comprehensive blockade of HER signaling pathways.
