The Phase III double-blind study randomised 808 people with HER2-positive mBC, which recurred after prior therapy in the adjuvant or neoadjuvant setting.
Genentech global product development head and chief medical officer Hal Barron said Perjeta helped people with HER2-positive metastatic breast cancer live longer and lengthened the time they lived without their disease worsening.
"The improvement in survival seen in the CLEOPATRA study is great news for patients and doctors, and reinforces our belief that Perjeta will improve the outlook for people with this devastating disease," Barron added.
The combination of Perjeta, Herceptin and docetaxel chemotherapy significantly improved overall survival, which is the secondary endpoint of the placebo-controlled study, in people with HER2-positive mBC, compared with Herceptin and chemotherapy.
The primary endpoint of the study was progression-free survival which demonstrated that people who received Perjeta in combination with Herceptin and docetaxel chemotherapy had a statistically significant 38% reduction in the risk of their disease worsening or death compared to people who received Herceptin and chemotherapy plus placebo.
Diarrhoea, hair loss, low white blood cell count with or without fever, upset stomach, fatigue, rash and peripheral neuropathy were the most common adverse reactions observed in the CLEOPATRA study.