Phase 2 results support ribociclib plus endocrine therapy (ET) as a preferred first-line treatment option for pre- and perimenopausal patients with aggressive, hormone receptor (HR)-positive, HER2-negative breast cancer, according to researchers.
In the phase 2 RIGHT Choice trial, ribociclib plus ET prolonged progression-free survival (PFS) by nearly 1 year, when compared with combination chemotherapy.
“[R]ibociclib plus endocrine therapy may offer more durable antitumor efficacy with better tolerability and compliance,” said Yen-Shen Lu, MD, PhD, of National Taiwan University Hospital in Taipei, when presenting these results at the San Antonio Breast Cancer Symposium 2022.
“Overall, these improvements in outcomes and tolerability should translate into an evolution of our standard of care for patients with hard-to-treat breast cancer, providing clinicians with guidance for treating this patient population,” Dr Lu added.
The RIGHT Choice trial (ClinicalTrials.gov Identifier: NCT03839823) enrolled pre- and perimenopausal patients with aggressive HR-positive, HER2-negative, advanced breast cancer who had received no prior systemic therapy.
The patients were randomly assigned (1:1) to receive ribociclib (600 mg daily, 3 weeks on and 1 week off) with ET (letrozole or anastrozole plus goserelin) or investigator’s choice of combination chemotherapy (docetaxel plus capecitabine, paclitaxel plus gemcitabine, or capecitabine plus vinorelbine).
The study included 222 patients, 112 in the ribociclib-ET arm (median age, 44 years) and 110 in the chemotherapy arm (median age, 43 years). Most patients had symptomatic visceral metastases (66.1% and 69.1%, respectively), and a minority had rapid disease progression (20.5% and 16.4%).
At the data cutoff, the median follow-up was 24.1 months. The proportion of patients still on treatment was 45.5% in the ribociclib-ET arm and 23.6% in the chemotherapy arm.
Overall survival data were immature at the data cutoff. However, the median PFS was significantly longer in the ribociclib-ET arm than in the chemotherapy arm — 24.0 months and 12.3 months, respectively (hazard ratio [HR], 0.54; 95% CI, 0.36-0.79; P =.0007).
The median time to treatment failure was significantly longer with ribociclib-ET than with chemotherapy as well — 18.6 months and 8.5 months, respectively (HR, 0.45; 95% CI, 0.32-0.63).
The overall response rate was 65.2% with ribociclib-ET and 60.0% with chemotherapy. The clinical benefit rate was 80.4% and 72.7%, respectively.
The rate of treatment-related serious adverse events was 1.8% with ribociclib-ET and 8.0% with chemotherapy. The rate of treatment-related events that led to discontinuation was 7.1% and 23.0%, respectively.
Disclosures: This research was supported by Novartis Pharmaceuticals. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Lu Y-S, Mahidin EIBM, Azim H, et al. Primary results from the randomized phase II RIGHT Choice trial of premenopausal patients with aggressive HR+/HER2− advanced breast cancer treated with ribociclib + endocrine therapy vs physician’s choice combination chemotherapy. Presented at SABCS 2022. December 6-10, 2022. Abstract GS1-10.