The primary purpose of this study was to assess the efficacy of ribociclib, as measured by progression free survival (PFS), in postmenopausal women with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer who received no prior treatment for advanced disease.
This was an international, multi-center, randomized, double-blinded, placebo controlled Phase III trial to determine the efficacy and safety of treatment with ribociclib plus letrozole versus placebo plus letrozole in postmenopausal women with HR+, HER2-negative advanced breast cancer who received no prior therapy for advanced disease. Eligible patients were randomized in 1:1 ratio to either ribociclib group or placebo group. Study treatment continued until disease progression, unacceptable toxicity, death, or discontinuation from the study treatment for any other reason. Participants who discontinued treatment due to reasons other than disease progression or withdrawal of consent for efficacy follow-up continued to be monitored until disease progression, death, withdrawal of consent, loss to follow-up, or subject/guardian decision (post-treatment efficacy follow-up). All participants who discontinued treatment were followed for survival until the predetermined number of overall survival (OS) events was reached. Following the final OS analysis (performed when approximately 400 deaths were recorded) and with protocol amendment 10 (dated 30-Apr-2021), participants and investigators were unblinded and those participants in the placebo arm had the opportunity to cross-over to the ribociclib arm to receive ribociclib plus letrozole. Cross-over was optional and was conducted at the investigator's discretion and upon participant consent.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
668
Ribociclib (600 mg, in three 200 mg hard gelatin capsules or tablets) was administered orally once daily on Days 1-21 of each 28-day cycle.
Letrozole (2.5 mg, tablets) was administered orally once daily on a continuous daily schedule (days 1-28 of each 28-day cycle)
Placebo (hard gelatin capsules or tablets) was administered orally once daily on Days 1-21 of each 28-day cycle.
Progression Free Survival (PFS) by Investigator Assessment
PFS was defined as the period starting from the date of randomization to the date of the first documented progression or death caused by any reason. In cases where patients did not experience an event, the PFS was censored at the date of the last adequate tumor assessment. Clinical deterioration without objective radiological evidence was not considered as documented disease progression.PFS was assessed by investigator assessment according to RECIST 1.1. The Kaplan-Meier method was used to estimate PFS, and the median PFS, along with 95% confidence intervals, was reported for each treatment group. A stratified Cox regression model was used to estimate the hazard ratio of PFS, along with 95% confidence interval
Time frame: Up to 23 months
Overall Survival (OS)
OS was defined as the time from the date of randomization to the date of death from any cause. In cases where the patient's death was not recorded, the OS value was censored at the date of the last known patient's survival status.OS was estimated using the Kaplan-Meier method. As per protocol, the final OS analysis was conducted after approximately 400 deaths were documented. The median OS, along with 95% confidence intervals, was reported for each treatment group.The distribution of OS between the two treatment arms was compared using a log-rank test at one-sided cumulative 2.5% level of significance. A stratified Cox regression was used to estimate the OS hazard ratio and the associated 95% CI.
Time frame: Up to approximately 87 months
Overall Response Rate (ORR) by Investigator Assessment
ORR is the percentage of participants with the best overall response of complete response (CR) or partial response (PR) according to RECIST 1.1 as per investigator assessment. . CR = Disappearance of all non-nodal target lesions. In addition, any pathological lymph nodes assigned as target lesions must have a reduction in short axis to \< 10 mm; PR = At least a 30% decrease in the sum of diameter of all target lesions, taking as reference the baseline sum of diameters.
Time frame: Up to 23 months
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Clinical Benefit Rate (CBR) by Investigator Assessment
Percentage of participants with complete response (CR) or partial response (PR) or stable disease (SD) lasting 24 weeks or longer as defined in RECIST 1.1 as per investigator assessment. CR = Disappearance of all non-nodal target lesions. In addition, any pathological lymph nodes assigned as target lesions must have a reduction in short axis to \< 10 mm; PR = At least a 30% decrease in the sum of diameter of all target lesions, taking as reference the baseline sum of diameters; SD = Neither sufficient shrinkage to qualify for PR or CR nor an increase in lesions which would qualify for progressive disease: PD = At least a 20% increase in the sum of diameter of all measured target lesions, taking as reference the smallest sum of diameter of all target lesions recorded at or after baseline. In addition to the relative increase of 20% the sum must also demonstrate an absolute increase of at least 5 mm.
Time frame: Up to 23 months
Time to Definitive Deterioration of Eastern Cooperative Oncology Group Performance Status (ECOG PS) by at Least One Category of the Score
ECOG PS categorized patients based on their ability to perform daily activities and self-care, with scores ranging from 0 to 5. A score of 0 indicated no restrictions in activity, while higher scores indicated increasing limitations. Time to definitive deterioration was defined as the time from the date of randomization to the date of the event, defined as experiencing an increase in ECOG PS by at least one category from the baseline or death. A deterioration was considered definitive if no improvements in the ECOG PS were observed at a subsequent time. The Kaplan-Meier method was used to estimate the distribution, and the median time to definitive deterioration, along with 95% confidence intervals, was reported for each treatment group. Patients receiving any further therapy prior to definitive worsening were censored at their date of last assessment prior to start of therapy. Patients that had not worsened at the data cutoff point were censored at the date of last assessment.
Time frame: From baseline up to 23 months
Time to Definitive 10% Deterioration in the Global Health Status/Quality of Life (GHS/QoL) Scale Score of the European Organization for Research and Treatment of Cancer's Core Quality of Life Questionnaire (EORTC QLQ-C30)
The EORTC QLQ-C30 is a questionnaire that includes 5 functional scales, 3 symptom scales, 1 GHS/QoL scale, and 6 single items. GHS/QoL scale score ranges between 0 and 100. A high score for GHS/QoL represents better functioning or QoL.The time to definitive 10% deterioration is defined as the time from the date of randomization to the date of event, which is defined as at least 10% relative to baseline worsening of the QoL score (without further improvement above the threshold) or death due to any cause. The Kaplan-Meier method was used to estimate the distribution, and the median time to definitive 10% deterioration, along with 95% confidence intervals, was reported for each treatment group. If a patient had not had an event, time to deterioration was censored at the date of the last adequate QoL evaluation.
Time frame: From baseline up to 23 months
Change From Baseline in the GHS/QoL Scale Score of the EORTC QLQ-C30
The EORTC QLQ-C30 is a questionnaire that includes 5 functional scales, 3 symptom scales, 1 GHS/QoL scale, and 6 single items. GHS/QoL scale score ranges between 0 and 100. A high score for GHS/QoL represents better functioning or QoL.The change from baseline in the GHS/QoL score was assesed. A positive change from baseline indicated improvement. For subjects who discontinued treatment earlier and without disease progression, post-treatment efficacy follow-up visits occurred every 8 weeks after End of treatment (EOT) during the initial 18 months since start of treatment, followed by visits every 12 weeks until disease progression or end of study.
Time frame: Baseline, every 2 cycles for 18 months, then every 3 cycles until last dose; at EOT (within 15 days from last dose);every 8 or 12 weeks post-treatment until progression (post-treatment efficacy visits), assessed up to 23 months. Cycle=28 days