Median progression-free survival was 23.8 months in the ribociclib arm compared with 13.0 months in the placebo arm.
The overall response rate was significantly higher among patients with measurable disease at baseline in the ribociclib arm compared with the placebo arm (51% vs 36%).
As expected, the most frequent adverse event was neutropenia, which was reported in 76% of patients in the ribociclib arm compared with 8% in the placebo arm. Grade 3/4 neutropenia was reported in 61% of patients in the ribociclib arm compared with 4% in the placebo arm, but it was asymptomatic in most patients.
Adding the cyclin-dependent kinase (CDK) 4/6 inhibitor ribociclib (Kisqali) to standard endocrine therapy with temporary ovarian suppression significantly improved progression-free survival for pre- and perimenopausal women with advanced hormone receptor–positive (HR-positive), HER2-negative breast cancer, according to data from the MONALEESA-7 phase III clinical trial presented by Tripathy et al at the 2017 San Antonio Breast Cancer Symposium (Abstract GS2-05).
Among the 672 patients enrolled in the clinical trial by Dr. Tripathy and colleagues, 335 were randomly assigned to ribociclib in combination with either tamoxifen or a nonsteroidal aromatase inhibitor (letrozole or anastrozole) and goserelin (Zoladex), and 337 were randomly assigned to placebo in combination with the same oral hormonal therapy options and goserelin. The primary endpoint of the trial was progression-free survival.
The study met its primary endpoint: Progression-free survival was significantly improved in the ribociclib arm compared with the placebo arm. Median progression-free survival was 23.8 months in the ribociclib arm compared with 13.0 months in the placebo arm.
Data are available for some of the secondary endpoints. For example, the overall response rate was significantly higher among patients with measurable disease at baseline in the ribociclib arm compared with the placebo arm (51% vs 36%).
As expected, the most frequent adverse event was neutropenia, which was reported in 76% of patients in the ribociclib arm compared with 8% in the placebo arm. Grade 3/4 neutropenia was reported in 61% of patients in the ribociclib arm compared with 4% in the placebo arm, but it was asymptomatic in most patients; neutropenia associated with fever and infection was reported in 2% of patients in the ribociclib arm and 1% in the placebo arm. Other adverse events included hot flashes, nausea, leukopenia, and joint pain/stiffness. Adverse events leading to permanent discontinuation of treatment occurred in 4% of patients in the ribociclib arm compared with 3% in the placebo arm.
“Longer follow-up is needed to determine whether the trial will meet its secondary endpoint of overall survival,” concluded Dr. Tripathy.