As reported by Yen-Shen Lu, MD, PhD, and colleagues in the Journal of Clinical Oncology, final results of the phase II RIGHT Choice study indicate that ribociclib plus endocrine therapy significantly prolonged progression-free survival vs combination chemotherapy in premenopausal women with clinically aggressive, hormone receptor (HR)-positive, HER2-negative advanced breast cancer.
Yen-Shen Lu, MD, PhD
Study Details
In the open-label trial, 222 patients from sites in 13 countries were randomly assigned between March 2019 and November 2021 to receive either:
- Ribociclib at 600 mg daily on a 3-week-on/1-week-off schedule, plus endocrine therapy with letrozole at 2.5 mg or anastrozole at 1 mg daily with goserelin at 3.6 mg on day 1 of each 28-day cycle (n = 112)
- Combination chemotherapy (n = 110) consisting of investigator’s choice of docetaxel plus capecitabine, paclitaxel plus gemcitabine, or capecitabine plus vinorelbine.
Overall, 68% of patients had symptomatic visceral metastases, 19% had rapid disease progression, 14% had symptomatic nonvisceral disease, and 48% had visceral crisis. The primary endpoint of the study was progression-free survival.
Key Findings
Median follow-up was 37.0 months. Median progression-free survival was 21.8 months (95% confidence interval [CI] = 17.4–26.7 months) in the ribociclib plus endocrine therapy group vs 12.8 months (95% CI = 10.1–18.4 months) in the chemotherapy group (hazard ratio = 0.61, 95% CI = 0.43–0.87, P = .003). Rates at 12 and 24 months were 68.9% vs 54.5% and 46.5% vs 23.6%, respectively.
Objective response rates were 66.1% in the ribociclib plus endocrine therapy group and 61.8% in the chemotherapy group. Clinical benefit rates were 81.3% vs 74.5%.
Higher rates of hematologic adverse events, including neutropenia and leukopenia, were observed in the ribociclib plus endocrine therapy group. Higher rates of nonhematologic adverse events, including such symptomatic adverse events as nausea, vomiting, diarrhea, and fatigue, were observed in the chemotherapy group.
The investigators concluded, “First-line ribociclib plus endocrine therapy showed a significant progression-free survival benefit, similar response rates, and better tolerability over combination chemotherapy in patients with clinically aggressive HR-positive/HER2-negative advanced breast cancer.”
Nagi S. El Saghir, MD, of the Naef K. Basile Cancer Institute, American University of Beirut Medical Center, Lebanon, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by Novartis Pharma AG. For full disclosures of the study authors, visit ascopubs.org.
