Effect of docetaxel duration on clinical outcomes: exploratory analysis of CLEOPATRA, a phase III randomized controlled trial

Combination pertuzumab, trastuzumab, and docetaxel (D) is considered standard first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. This post hoc, exploratory analysis of CLEOPATRA study data evaluated the clinical effects of D treatment duration within this regimen. The clinical benefits of pertuzumab and trastuzumab by different durations of D treatment were also evaluated. Patients with HER2-positive metastatic breast cancer received trastuzumab and D plus pertuzumab or placebo. Clinical outcomes were analyzed by the number of D cycles that patients received (6D). Progression-free survival (PFS) and overall survival (OS) for each treatment arm within each D cycle group were estimated using the Kaplan-Meier approach. Time-dependent, multivariate Cox regression was applied to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for HER2-targeted therapy and D cycle groups. Overall, 804 patients received6D (n = 475) cycles. After adjusting for pertuzumab benefits versus placebo (PFS HR= 0.61, 95% CI 0.51-0.74, P < 0.0001; OS HR= 0.60, 95% CI, 0.49-0.74, P < 0.0001),>6D versus 6D cycles was not associated with statistically significant improvements in PFS (HR= 0.80, 95% CI 0.63-1.01, P = 0.0640) or OS (HR= 0.88, 95% CI 0.69-1.12, P = 0.3073). Consistent improvements in PFS and OS were observed with pertuzumab versus placebo, irrespective of D duration. The HRs for PFS were 0.395, 0.615, and 0.633 for6D cycles, respectively (P < 0.05 for all D cycle groups). Corresponding HRs for OS were 0.577, 0.700, and 0.612, respectively (P < 0.05 for6D). After accounting for pertuzumab benefits, more than six cycles of D treatment was not associated with significant improvements in either PFS or OS compared with six cycles. The addition of pertuzumab to trastuzumab improved clinical outcomes versus trastuzumab plus placebo, regardless of D treatment duration. CLINICALTRIALS. NCT00567190.