Study of Efficacy and Safety in Premenopausal Women With Hormone Receptor Positive, HER2-negative Advanced Breast Cancer

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 189 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.

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 local 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.

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 and local 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 to response is the time from the date of randomization to the first documented response (CR or PR, which must be confirmed subsequently) according to RECIST 1.1 as per local assessment. The Kaplan-Meier method was used to estimate TTR, and the median TTR, along with 95% confidence intervals, was reported for each treatment group. Participants who did not achieve a confirmed response were censored at the maximum follow-up time for patients who had a PFS event (i.e. either progressed or died due to any cause) or at the date of last adequate tumor assessment otherwise. 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.

DOR was defined as the time from the first documented response (CR or PR) to the first documented progression or death due to underlying cancer as defined in RECIST 1.1 per investigator assessment. The Kaplan-Meier method was used to estimate DOR, and the median DOR, along with 95% confidence intervals, was reported for each treatment group. If a participant had not had an event, duration was censored at the date of last adequate tumor 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.

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.

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.

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 assessed. A positive change from baseline indicated improvement. For subjects who discontinued treatment without disease progression, post-treatment efficacy visits occurred every 8 weeks during the initial 18 months since start of treatment, followed by visits every 12 weeks until disease progression.