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.)
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
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