Importance: Prospective assessment of treatments known to benefit patients in global clinical trials in specific racial groups is essential.
Objective: To compare the efficacy, safety, and tolerability of adding pertuzumab to trastuzumab and docetaxel vs placebo, trastuzumab, and docetaxel in Asian patients with ERBB2-positive early or locally advanced breast cancer.
Design, setting, and participants: This multicenter, double-blind, placebo-controlled phase 3 trial enrolled 329 women with ERBB2-positive early (T2-3, N0-1, M0) or locally advanced breast cancer (T2-3, N2 or N3, M0; T4, any N, M0) and primary tumor larger than 2 cm from March 14, 2016, to March 13, 2017. Analysis of the primary end point was performed on an intention-to-treat basis.
Interventions: Before surgery, patients received 4 cycles of intravenous pertuzumab (840-mg loading dose and 420-mg maintenance doses), trastuzumab (8-mg/kg loading dose and 6-mg/kg maintenance doses), and docetaxel (75 mg/m2) or intravenous placebo, trastuzumab, and docetaxel every 3 weeks. After surgery, patients received 3 cycles of intravenous fluorouracil, epirubicin, and cyclophosphamide followed by 13 cycles of the same intravenous anti-ERBB2 therapy (pertuzumab and trastuzumab or placebo and trastuzumab) for up to 1 year.
Main outcomes and measures: The primary end point was independent review committee-assessed total pathologic complete response rate. The 2-sided Cochran-Mantel-Haenszel test, stratified by disease category and hormone receptor status, was used to compare rates between treatment groups.
Results: In total, 329 female patients were randomized (pertuzumab, 219; and placebo, 110; mean [SD] age, 48.8 [9.5] years). In the intention-to-treat population, total pathologic complete response rates were 39.3% (86 of 219) in the pertuzumab group and 21.8% (24 of 110) in the placebo group (difference, 17.5% [95% CI, 6.9%-28.0%]; P = .001). Of the most common grade 3 or higher adverse events, there was a higher incidence of neutropenia in the pertuzumab group (83 of 218 [38.1%] vs 36 of 110 [32.7%]). Serious adverse events were reported in 10.1% of patients (22 of 218) in the pertuzumab group and 8.2% of patients (9 of 110) in the placebo group.
Conclusions and relevance: Treatment with pertuzumab, trastuzumab, and docetaxel resulted in a statistically significant improvement in the total pathologic complete response rate vs placebo, trastuzumab, and docetaxel for the neoadjuvant treatment of ERBB2-positive early or locally advanced breast cancer in Asian patients. Safety data were in line with the known pertuzumab safety profile and generally comparable between treatment groups. The PEONY trial adds to the totality of data showing the benefit of the pertuzumab regimen.
Trial registration: ClinicalTrials.gov identifier: NCT02586025.