Abstract
BackgroundTrastuzumab and fulvestrant combination therapy is one of the treatment options for patients with hormone receptor- and human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer; however, there are limited studies evaluating the efficacy of this combination therapy.MethodsWe retrospectively reviewed the data of women with hormone receptor- and HER2-positive metastatic breast cancer who received trastuzumab and fulvestrant combination therapy between August 1997 and August 2020 at the Cancer Institute Hospital. The primary endpoint of this study was progression-free survival, and the secondary endpoints were response rate, overall survival and safety.ResultsWe reviewed the data of 1612 patients with recurrent or metastatic breast cancer, of which 118 patients were diagnosed with hormone receptor- and HER2-positive breast cancer. Of these, 28 patients who received trastuzumab and fulvestrant combination therapy were eligible for this study. The median treatment line for advanced breast cancer was 6 (range, 1–14), the median progression-free survival was 6.4 months (95% confidence interval [CI], 3.46–8.17), and the median overall survival was 35.3 months (95% CI, 20.0–46.7). Of the 28 patients, partial response was observed in 1 (4%), stable disease in 17 (61%), and progressive disease in 10 (36%) patients. The disease control rate was 64%. Adverse events of grade ≥ 3 were not observed.ConclusionsTrastuzumab and fulvestrant combination therapy showed moderate clinical efficacy and no severe toxicity after standard anti-HER2 treatment, which is a reasonable treatment option for patients with hormone receptor- and HER2-positive metastatic breast cancer. These data contribute to understanding the efficacy of trastuzumab and fulvestrant combination therapy as control data for further development of anti-HER2 agents plus hormone therapy.
Highlights
Trastuzumab and fulvestrant combination therapy is one of the treatment options for patients with hormone receptor- and human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer; there are limited studies evaluating the efficacy of this combination therapy
Trastuzumab was previously administered for advanced breast cancer to all patients, pertuzumab to four patients, and trastuzumab emtansine (T-DM1) to 10 patients
The median progression-free survival (PFS) after Trastuzumab emtansine (T-DM1) treatment was 6.1 months and median overall survival (OS) was 23.7, which are comparable with the PFS and OS of trastuzumab and fulvestrant combination therapy in the current study
Summary
Trastuzumab and fulvestrant combination therapy is one of the treatment options for patients with hormone receptor- and human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer; there are limited studies evaluating the efficacy of this combination therapy. Breast cancer has been divided into subtypes depending on the presence of hormone receptors (HRs) for estrogen and progesterone and HER2 expression [2]. There are four major subtypes of breast cancer: HR-positive HER2-negative (HR + HER2−), HR-positive HER2positive (HR + HER2+), HR-negative HER2-positive (HR − HER2+), and HR-negative HER2-negative (triple-negative breast cancer). The HER2-positive subtype accounts for 15–20% of all breast cancer subtypes [3]. Half of the HER2-positive breast cancers express HRs [4]. HR + HER2+ breast cancer account for approximately 10% of all breast cancer cases [5, 6]
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