Capecitabine Versus Endocrine Therapy as a Maintenance Therapy for Metastatic Breast Cancer

ET and CT are used as standard maintenance therapy for HR-positive and HER-negative MBC in clinical practice, and there was no prospective study data on which is better, according to the study authors.

A study analyzing hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) found endocrine therapy (ET) maintenance has a better survival benefit than chemotherapy (CT) after first-line salvage combined chemotherapy, especially for ET-sensitive and non-visceral involved cases, according to a study presented at the 2020 San Antonio Breast Cancer Symposium.

ET and CT are used as standard maintenance therapy for HR-positive and HER-negative MBC in clinical practice, and there was no prospective study data on which is better, according to the study authors.

The OVERSTEP trial enrolled 181 patients in China between the ages of 18 and 70 years without chemotherapy for advanced breast cancer (ABC)/MBC previously, histologically confirmed metastatic HR-positive and HER2-negative breast cancer, and ECOG performance status of 0-1. Further, the patients received capecitabine plus another chemotherapy drug as first-line salvage chemotherapy for at least 4 cycles.

The patients’ responses—complete response, partial response, and stable disease—carried maintenance treatment next, randomly assigned 1:1 to receive either capecitabine single or endocrine therapy. Further, randomization was done centrally with stratification by endocrine resistance and visceral metastasis. The primary endpoint was progression-free survival (PFS) and analyses were based on all patients who received at least 1 dose maintenance therapy.

The results showed that 75.14% of patients were randomized after combined chemotherapy to capecitabine single or endocrine therapy groups for maintenance treatment and 24.86% patients had progressive disease after combined chemotherapy.

After a median follow-up of 24.3 months in the endocrine maintenance therapy group and 24.1 months in the capecitabine maintenance therapy group, the hazard ratio for PFS was 0.625, median PFS was 17.5 months in endocrine maintenance therapy group, and 12.2 months in capecitabine maintenance therapy group.

In the endocrine sensitive group, the hazard ratio for PFS was 0.515, median PFS was 29.3 months in endocrine maintenance therapy group, and 14.8 months in capecitabine maintenance therapy group. The endocrine resistance group had a hazard ratio for PFS at 0.791, median PFS of 13.6 months in endocrine maintenance therapy group, and 12.0 months in capecitabine maintenance therapy group.

Further, the visceral metastasis group had a hazard ratio for PFS at 0.668, median PFS was 14.3 months in endocrine maintenance therapy group, and 11.0 months in capecitabine maintenance therapy group. In the non-visceral metastasis group, the hazard ratio for PFS was 0.54, median PFS was 25.3 months in endocrine maintenance therapy group, and 17.0 months in capecitabine maintenance therapy group.

The study authors concluded that ET maintenance is the first choice for ABC/MBC after first-line combined chemotherapy.

REFERENCE

Huang J, et al. Primary analysis of OVERSTEP: A multicenter, randomized clinical trial of capecitabine or endocrine therapy as a maintenance therapy after the 1stline chemotherapy in hormone receptor positive and HER2-negative advanced/metastatic breast cancer. 2020 San Antonio Breast Cancer Symposium.