Dr Ahn on Outcomes With Ovarian Function Suppression in HER2+ Breast Cancer

Sung Gwe Ahn, MD, PhD, professor, Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, discusses findings from an exploratory analysis of ovarian function suppression (OFS) in patients with hormone receptor–positive, HER2-positive breast cancer enrolled in the phase 3 HERA trial (NCT00045032), as well as the future implications of these findings.

HERA enrolled patients with locally determined HER2-positive invasive early breast cancer who had previously undergone surgery in addition to neoadjuvant or adjuvant chemotherapy with or without radiotherapy. Patients needed to have centrally confirmed HER2 3+ disease per immunohistochemistry or fluorescence in situ hybridization. Patients were randomly assigned to undergo observation (overall population = 1698; premenopausal population = 310) or receive trastuzumab (Herceptin) for 1 year (n = 1703; n = 333) or 2 years (n = 1701; n = 322).

This OFS analysis assessed outcomes with various OFS methods in premenopausal patients who had previously been enrolled in the HERA trial. At a median follow-up of 11.0 years, the disease-free survival (DFS) and overall survival (OS) rates among patients who received OFS-based endocrine therapy (n = 464) were superior to those who received tamoxifen alone (n = 501). The 10-year DFS rates in these respective populations were 70.9% and 59.6% (HR, 0.68; 95% CI, 0.53-0.88). The 10-year OS rates in these respective populations were 84.7% and 74.0% (HR, 0.64; 95% CI, 0.46-0.89).

Additionally, the benefit with OFS was consistent regardless of length of whether patients had received prior trastuzumab. Among patients who received trastuzumab (n = 655), the 10-year DFS rates were 72.4% for those who also received OFS-based endocrine therapy vs 63.6% for those who received tamoxifen alone (HR, 0.69; 95% CI, 0.52-0.91). For patients who did not receive trastuzumab (n = 310), these respective rates were 67.9% and 50.5% (HR, 0.56; 95% CI, 0.39-0.81). The 10-year OS rates were 85.1% for patients who received trastuzumab alongside OFS-based endocrine therapy vs 75.8% among those who received tamoxifen alone (HR, 0.60; 95% CI, 0.41-0.87). Among patients who did not receive trastuzumab, these respective rates were 84.0% and 69.9% (HR, 0.47; 95% CI, 0.28-0.78).

Disclosures: Dr Ahn reports receiving speaking honoraria from and performing advisory roles for AstraZeneca, Roche, Eli Lilly, Novartis, Gencurix, MSD, NEED, BIXINK, Celltrion, and Jeil Pharmaceutical; owning stock in Celltrion and GI Cell; receiving research funding from the National Research Fund of Korea Government, Yoohan Pharmaceutical, and Gencurix; serving as the coordinating PI for INTERSTELLAR and PRESERVE; and serving as the chair of the educational committee of the Korean Breast Cancer Society.