BACKGROUND The anti–human epidermal growth factor receptor 2 (HER2) humanized monoclonal antibody trastuzumab improves the outcome in patients with HER2-positive metastatic breast cancer. However, most cases of advanced disease eventually progress. Pertuzumab, an anti-HER2 humanized monoclonal antibody that inhibits receptor dimerization, has a mechanism of action that is complementary to that of trastuzumab, and combination therapy with the two antibodies has shown promising activity and an acceptable safety profile in phase 2 studies involving patients with HER2-positive breast cancer. METHODS We randomly assigned 808 patients with HER2-positive metastatic breast cancer to receive placebo plus trastuzumab plus docetaxel (control group) or pertuzumab plus trastuzumab plus docetaxel (pertuzumab group) as first-line treatment until the time of disease progression or the development of toxic effects that could not be effectively managed. The primary end point was independently assessed progression-free survival. Secondary end points included overall survival, progression-free survival as assessed by the investigator, the objective response rate, and safety. RESULTS The median progression-free survival was 12.4 months in the control group, as compared with 18.5 months in the pertuzumab group (hazard ratio for progression or death, 0.62; 95% confidence interval, 0.51 to 0.75; P<0.001). The interim analysis of overall survival showed a strong trend in favor of pertuzumab plus trastuzumab plus docetaxel. The safety profile was generally similar in the two groups, with no increase in left ventricular systolic dysfunction; the rates of febrile neutropenia and diarrhea of grade 3 or above were higher in the pertuzumab group than in the control group. CONCLUSIONS The combination of pertuzumab plus trastuzumab plus docetaxel, as compared with placebo plus trastuzumab plus docetaxel, when used as first-line treatment for HER2-positive metastatic breast cancer, significantly prolonged progression-free survival, with no increase in cardiac toxic effects.

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BACKGROUND In patients with metastatic breast cancer that is positive for human epidermal growth factor receptor 2 (HER2), progression-free survival was significantly improved after first-line therapy with pertuzumab, trastuzumab, and docetaxel, as compared with placebo, trastuzumab, and docetaxel. Overall survival was significantly improved with pertuzumab in an interim analysis without the median being reached. We report final prespecified overall survival results with a median follow-up of 50 months. METHODS We randomly assigned patients with metastatic breast cancer who had not received previous chemotherapy or anti-HER2 therapy for their metastatic disease to receive the pertuzumab combination or the placebo combination. The secondary end points of overall survival, investigator-assessed progression-free survival, independently assessed duration of response, and safety are reported. Sensitivity analyses were adjusted for patients who crossed over from placebo to pertuzumab after the interim analysis. RESULTS The median overall survival was 56.5 months (95% confidence interval [CI], 49.3 to not reached) in the group receiving the pertuzumab combination, as compared with 40.8 months (95% CI, 35.8 to 48.3) in the group receiving the placebo combination (hazard ratio favoring the pertuzumab group, 0.68; 95% CI, 0.56 to 0.84; P<0.001), a difference of 15.7 months. This analysis was not adjusted for crossover to the pertuzumab group and is therefore conservative. Results of sensitivity analyses after adjustment for crossover were consistent. Median progression-free survival as assessed by investigators improved by 6.3 months in the pertuzumab group (hazard ratio, 0.68; 95% CI, 0.58 to 0.80). Pertuzumab extended the median duration of response by 7.7 months, as independently assessed. Most adverse events occurred during the administration of docetaxel in the two groups, with long-term cardiac safety maintained. CONCLUSIONS In patients with HER2-positive metastatic breast cancer, the addition of per tuzumab to trastuzumab and docetaxel, as compared with the addition of placebo, significantly improved the median overall survival to 56.5 months and extended the results of previous analyses showing the efficacy of this drug combination. (Funded by F. Hoffmann–La Roche and Genentech; CLEOPATRA ClinicalTrials.gov number, NCT00567190.)

The combination of P with H and standard chemotherapy resulted in low rates of symptomatic LVSD.

Summary Background Primary results from the randomised, double-blind phase 3 study CLEOPATRA demonstrated significantly improved median progression-free survival (PFS) with pertuzumab plus trastuzumab plus docetaxel versus placebo plus trastuzumab plus docetaxel in patients with human epidermal growth factor receptor 2 (HER2)-positive first-line metastatic breast cancer (MBC). Overall survival (OS) data at the primary analysis showed a strong trend in favour of the pertuzumab arm but did not reach statistical significance. Here we report confirmatory OS results after one additional year of follow-up. Methods Patients were randomly assigned to study treatment. OS and investigator-assessed PFS were analysed using the Kaplan-Meier approach and log-rank tests stratified by geographic region and prior treatment status. This trial is registered with ClinicalTrials.gov, NCT00567190. Findings In the intent-to-treat population (808 patients), 267 deaths had occurred at data cut-off (placebo arm: 154 of 406 [37·9%], pertuzumab arm: 113 of 402 [28·1%]). Treatment with pertuzumab plus trastuzumab plus docetaxel resulted in a 34% reduction in the risk of death during the course of the study (HR=0·66; 95% CI 0·52–0·84; p=0·0008). Median OS was 37·6 months in the placebo arm and was not yet reached in the pertuzumab arm. A descriptive follow-up analysis of investigator-assessed PFS showed a median PFS of 12·4 and 18·7 months in the placebo versus pertuzumab arm (HR=0·69; 95% CI 0·58–0·81). No new safety concerns were identified with one additional year of follow-up. Adverse events were similar to those reported at the primary analysis with respect to incidence, severity, and specificity. Interpretation This OS analysis demonstrated statistically significant and clinically meaningful survival benefit with pertuzumab plus trastuzumab plus docetaxel in patients with HER2-positive MBC. Updated analyses of investigator-assessed PFS and safety were consistent with the results from the primary analysis. Funding F. Hoffmann-La Roche/Genentech