Dataset Information

A Phase II Study of Fulvestrant 500 mg as Maintenance Therapy in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Patients with Advanced Breast Cancer After First-Line Chemotherapy.

ABSTRACT:

Lessons learned

Fulvestrant 500 mg maintenance therapy showed a clinical benefit rate of 76% and median progression-free survival of 16.1 months in patients who achieved objective responses or disease control after first-line chemotherapy. Adverse events with fulvestrant maintenance therapy were consistent with the known safety profile of the drug.

Background

Evidence for maintenance hormonal therapy after chemotherapy for estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer is scarce. This study aimed to evaluate the efficacy of fulvestrant 500 mg maintenance therapy in patients after first-line chemotherapy.

Methods

We enrolled postmenopausal women with ER-positive/HER2-negative advanced breast cancer who attained tumor responses or disease control with four to eight cycles of chemotherapy as first-line treatment. Fulvestrant 500 mg was injected on days 1, 15, and 29 and every 28 (±3) days thereafter. The primary endpoint was the clinical benefit rate (CBR); the secondary endpoints included the objective response rate (ORR), progression-free survival (PFS), and safety.

Results

We included 58 patients; the median follow-up duration was 32.6 months. The CBR since commencing fulvestrant maintenance therapy was 76% (95% confidence interval [CI], 63%-86%), and ORR was 14% (95% CI, 6%-25%); eight patients achieved partial response. The median PFS for fulvestrant maintenance therapy was 16.1 months (95% CI, 10.3-21.0 months). Thirty-nine patients (67%) reported at least one adverse event, of which most were grade 1/2, whereas three patients (5%) reported grade 3 adverse events.

Conclusion

Fulvestrant 500 mg is a feasible and promising hormonal maintenance strategy in patients with ER-positive/HER2-negative advanced breast cancer who have no disease progression after first-line chemotherapy.

SUBMITTER: Xu F

PROVIDER: S-EPMC8100565 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeTo compare overall survival (OS) for fulvestrant 500 mg versus anastrozole as first-line endocrine therapy for advanced breast cancer.Patients and methodsThe Fulvestrant First-Line Study Comparing Endocrine Treatments (FIRST) was a phase II, randomized, open-label, multicenter trial. Postmenopausal women with estrogen receptor-positive, locally advanced/metastatic breast cancer who had no previous therapy for advanced disease received either fulvestrant 500 mg (days 0, 14, 28, and every 28 days thereafter) or anastrozole 1 mg (daily). The primary end point (clinical benefit rate [72.5% and 67.0%]) and a follow-up analysis (median time to progression [23.4 months and 13.1 months]) have been reported previously for fulvestrant 500 mg and anastrozole, respectively. Subsequently, the protocol was amended to assess OS by unadjusted log-rank test after approximately 65% of patients had died. Treatment effect on OS across several subgroups was examined. Tolerability was evaluated by adverse event monitoring.ResultsIn total, 205 patients were randomly assigned (fulvestrant 500 mg, n = 102; anastrozole, n = 103). At data cutoff, 61.8% (fulvestrant 500 mg, n = 63) and 71.8% (anastrozole, n = 74) had died. The hazard ratio (95% CI) for OS with fulvestrant 500 mg versus anastrozole was 0.70 (0.50 to 0.98; P = .04; median OS, 54.1 months v 48.4 months). Treatment effects seemed generally consistent across the subgroups analyzed. No new safety issues were observed.ConclusionThere are several limitations of this OS analysis, including that it was not planned in the original protocol but instead was added after time-to-progression results were analyzed, and that not all patients participated in additional OS follow-up. However, the present results suggest fulvestrant 500 mg extends OS versus anastrozole. This finding now awaits prospective confirmation in the larger phase III FALCON (Fulvestrant and Anastrozole Compared in Hormonal Therapy Naïve Advanced Breast Cancer) trial (ClinicalTrials.gov identifier: NCT01602380).