End-of-study analysis from the phase III, randomized, double-blind, placebo (Pla)-controlled CLEOPATRA study of first-line (1L) pertuzumab (P), trastuzumab (H), and docetaxel (D) in patients (pts) with HER2-positive metastatic breast cancer (MBC).

Abstract

1020 Background: Progression-free and overall survival (PFS and OS) were significantly improved with 1L P + H + D v Pla + H + D in 808 pts with HER2-positive MBC in CLEOPATRA (NCT00567190). OS was increased by an unprecedented 15.7 mo (median 56.5 mo with P + H + D v 40.8 mo with Pla + H + D; HR 0.68; 95% CI 0.56, 0.84; p < .001) with a median follow-up of 50 mo [Swain et al. NEJM 2015]). Here we report the end-of-study analysis with a median follow-up of 99 mo (max 120 mo). Methods: In this descriptive analysis, OS was compared between arms using the log-rank test, stratified by prior treatment status and geographic region. The Kaplan–Meier approach was used to estimate median OS, and a stratified Cox proportional hazards model was used to estimate the HR and 95% CIs. Subgroup analyses of OS were performed for stratification factors and other baseline characteristics. Results: Clinical cutoff was Nov 23, 2018. Since Jul 2012, 50 pts crossed from the Pla to the P arm. These pts are counted in the Pla arm for efficacy analyses and up to the first dose of P for safety analyses. The OS HR was 0.69 (95% CI 0.58, 0.82), favoring P + H + D. Median OS was 57.1 mo in the P arm (402 pts) and 40.8 mo in the Pla arm (406 pts; Δ 16.3 mo). The 8-year landmark OS rates were 37% and 23%, respectively. The OS benefit in predefined subgroups, including in pts previously treated with H in the (neo)adjuvant setting (88 pts, HR 0.86; 95% CI 0.51, 1.43), remained consistent with the overall result and previous reports. The overall safety profile of P + H + D was consistent with the known P safety profile. There was only one new serious adverse event suggestive of congestive heart failure (onset ~77 mo on treatment in the P arm, resolution in 34 days, pt continued on study medication) and one new symptomatic left ventricular systolic dysfunction (onset ~46 mo after crossing to the P arm, resolution in 34 days) since the previous analysis. Conclusions: The OS improvement with 1L P + H + D v Pla + H + D for pts with HER2-positive MBC was maintained after an additional 4 years of long-term follow-up, as were the safety and cardiac safety profiles. Clinical trial information: NCT00567190.