Re: International Guidelines for Management of Metastatic Breast Cancer: Combination vs Sequential Single-Agent Chemotherapy

Metastatic breast cancer is a heterogeneous disease, and treatment decisions depend on several individualized patient and tumor characteristics. Although combination therapy often shows improved response rates in metastatic breast cancer, few studies have shown superiority in overall survival. The choice of combination versus sequential single-agent treatment, therefore, must consider many factors, with no one strategy right for all patients. This article reviews several important clinical trials that address this issue, and argues for single-agent sequential therapy for most patients with metastatic breast cancer.

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Real-world survival outcomes of heavily pretreated patients with refractory HR+, HER2−metastatic breast cancer receiving single-agent chemotherapy—a comparison with MONARCH 1

Breast Cancer Research and Treatment ◽

10.1007/s10549-020-05838-5 ◽

2020 ◽

Vol 184 (1) ◽

pp. 161-172

Author(s):

Hope S. Rugo ◽

Veronique Dieras ◽

Javier Cortes ◽

Debra Patt ◽

Hans Wildiers ◽

...

Keyword(s):

Breast Cancer ◽

Metastatic Breast Cancer ◽

Real World ◽

Single Agent ◽

Metastatic Breast ◽

Clinical Context ◽

Eligibility Criteria ◽

The Real ◽

Heavily Pretreated ◽

Single Agent Chemotherapy

Abstract Purpose In MONARCH 1 (NCT02102490), single-agent abemaciclib demonstrated promising efficacy activity and tolerability in a population of heavily pretreated women with refractory HR+, HER2− metastatic breast cancer (MBC). To help interpret these results and put in clinical context, we compared overall survival (OS) and duration of therapy (DoT) between MONARCH 1 and a real-world single-agent chemotherapy cohort. Methods The real-world chemotherapy cohort was created from a Flatiron Health electronic health records-derived database based on key eligibility criteria from MONARCH 1. The chemotherapies included in the cohort were single-agent capecitabine, gemcitabine, eribulin, or vinorelbine. Results were adjusted for baseline demographics and clinical differences using Mahalanobis distance matching (primary analysis) and entropy balancing (sensitivity analysis). OS and DoT were analyzed using the Kaplan–Meier method and Cox proportional hazards regression. Results A real-world single-agent chemotherapy cohort (n = 281) with eligibility criteria similar to the MONARCH 1 population (n = 132) was identified. The MONARCH 1 (n = 108) cohort was matched to the real-world chemotherapy cohort (n = 108). Median OS was 22.3 months in the abemaciclib arm versus 13.6 months in the matched real-world chemotherapy cohort with an estimated hazard ratio (HR) of 0.54. The median DoT was 4.1 months in MONARCH 1 compared to 2.9 months in the real-world chemotherapy cohort with HR of 0.76. Conclusions This study demonstrates an approach to create a real-world chemotherapy cohort suitable to serve as a comparator for trial data. These exploratory results suggest a survival advantage and place the benefit of abemaciclib monotherapy in clinical context.

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