Anti-hormonal maintenance treatment with the CDK4/6 inhibitor ribociclib after 1st line chemotherapy in hormone receptor positive / HER2 negative metastatic breast cancer: A phase II trial (AMICA)

Abstract

PurposeThis phase II study evaluated the impact of adding ribociclib to maintenance endocrine therapy (ET) treatment of physicians’ choice following the first palliative chemotherapy in pre- and post-menopausal women with hormone receptor positive (HR+)/human epidermal growth factor 2 negative (HER2-) metastatic breast cancer (mBC). Patients and methodsThe initial randomized study design was later amended into a single-arm study, and all subsequent patients received ribociclib and ET. The primary end point was locally assessed progression-free survival (PFS). Secondary end points included overall survival (OS), clinical benefit rate (CBR), safety, compliance, and quality of life (QoL). ResultsA total of 43 patients received ribociclib + ET and 10 patients received ET only. Median PFS was 12.4 months [95% CI 8.7–24.4] for patients who received ribociclib + ET and 4.75 months [95% CI 1.0–10.3] for those who received ET only. Median OS was not reached for patients who received ribociclib + ET, and 28 (65.1%) patients experienced clinical benefit [95% CI 49.1–79.0]. For patients who received ribociclib + ET, grade 3–4 hematological adverse events (AEs) occurred in 25 (58.1%) patients, and grade 3–4 non-hematological AEs occurred in 17 (39.5%) patients. During the study, 15 patients died – 14 of whom due to tumor-related reasons, and one patient due to pneumonia, which was not treatment-related. ConclusionThe results of the AMICA study show a promising efficacy and safety of maintenance treatment with ribociclib added to ET after at least stable disease following the first metastatic chemotherapy in patients with HR+/HER2-mBC. Trial registrationAnti-hormonal Therapy With Ribociclib in HR-positive/HER2- Negative Metastatic Breast Cancer (AMICA), NCT03555877, https://clinicaltrials.gov/ct2/show/NCT03555877.