Fulvestrant with or without anti-HER2 therapy in patients in a postmenopausal hormonal state and with ER-positive HER2-positive advanced or metastatic breast cancer: A subgroup analysis of data from the Safari study (JBCRG-C06).

BACKGROUND: The role of endocrine therapy in the treatment of patients in a postmenopausal hormonal state and with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-positive advanced or metastatic breast cancer (AMBC) is unclear. METHODS: We analyzed the data from 94 patients with ER-positive HER2-positive AMBC enrolled in the Safari study (UMIN000015168), a retrospective cohort study of 1072 ER-positive AMBC patients in a postmenopausal hormonal state who received fulvestrant 500 mg (F500): (1) to compare time to treatment failure (TTF) and overall survival (OS) by treatment group, and TTF by treatment line; (2) in patients who received endocrine therapy (including F500) or anti-HER2 therapy as initial systemic therapy before chemotherapy, to investigate relations between TTF for the first-line therapy or time to chemotherapy (TTC) and OS; (3) to investigate factors associated with OS. RESULTS: The TTF was longer in the patients treated with F500 as first- or second-line therapy (n = 20) than in those who received later-line F500 therapy (n = 74) (6.6 vs. 3.7 months; HR, 1.98; p = 0.014). In the 59 patients who received endocrine therapy or anti-HER2 therapy as initial systemic therapy before chemotherapy, those with TTC ≥3 years had longer median OS than those with TTC <3 years (10.5 vs. 5.9 years; HR, 0.32; p = 0.001). Longer TTC was associated with prolonged OS. CONCLUSIONS: In patients with ER-positive HER2-positive AMBC enrolled in the Safari study, TTF was longer in patients who received F500 as first- or second-line therapy. In patients who received chemotherapy-free initial systemic therapy, the prolonged OS in those with TTC ≥3 years suggests that this value may be a helpful cut-off for indicating clinical outcomes.

Rechallenge of anti-PD-1/PD-L1 antibody showed a good response to metastatic breast cancer: a case report.

Rechallenge of immune checkpoint inhibitors has been reported for neoplasms other than breast cancer. Reported here is a case of a 55-year old woman diagnosed as having triple-negative right breast cancer with multiple metastases including lung. Atezolizumab and nab-paclitaxel were administered followed by epirubicin-cyclophosphamide. With subsequent eribulin, the overall best response was progressive disease, and curative surgical resection was performed. Three months after surgery (1.5 years after initial response of lung metastasis), right lung metastasis emerged at a site different from baseline. Based on the microsatellite instability-high status, pembrolizumab was administered and showed a good response. The patient has been treated with pembrolizumab, maintaining partial response, for over 9 months, which suggests the benefit of immune checkpoint inhibitors rechallenge in breast cancer.