Slamon DJ, et al. - In patients who were treatment naive or had received up to one line of prior endocrine therapy in the advanced setting, authors assessed ribociclib plus fulvestrant in patients with hormone receptor-positive/human epidermal growth factor receptor 2–negative advanced breast cancer. In hormone receptor–positive/human epidermal growth factor receptor 2–negative advanced breast cancer, a new first- or second-line treatment option could be offered by ribociclib plus fulvestrant.

Methods

• Experts randomly assigned patients at a 2:1 ratio to ribociclib plus fulvestrant or placebo plus fulvestrant.
• The locally assessed progression-free survival was the primary end point, and overall survival, overall response rate, and safety were the secondary end points.

Results

• A total of 484 postmenopausal women were randomly given ribociclib plus fulvestrant, and 242 were given placebo plus fulvestrant.
• Results demonstrated a significant improvement in median progression-free survival with ribociclib plus fulvestrant vs placebo plus fulvestrant, at 20.5 months (95% CI, 18.5 to 23.5 months) vs 12.8 months (95% CI, 10.9 to 16.3 months), respectively (hazard ratio, 0.593; 95% CI, 0.480 to 0.732; P < .001).
• As per data, in patients who were treatment naïve in the advanced setting, consistent treatment effects were observed (hazard ratio, 0.577; 95% CI, 0.415 to 0.802), as well as in patients who had received up to one line of prior endocrine therapy for advanced disease (hazard ratio, 0.565; 95% CI, 0.428 to 0.744).
• Researchers noted that the overall response rate was 40.9% for the ribociclib plus fulvestrant arm and 28.7% for placebo plus fulvestrant among patients with measurable disease.
• Neutropenia (46.6% vs 0%) and leukopenia (13.5% vs 0%) were the grade 3 adverse events reported in ≥10% of patients in either arm (ribociclib plus fulvestrant vs placebo plus fulvestrant); the only grade 4 event reported in ≥ 5% of patients was neutropenia (6.8% vs 0%).