Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up

Key Points

• Assess the extended efficacy, safety, and quality-of-life outcomes of first-line palbociclib plus letrozole versus placebo plus letrozole in ER+/HER2- advanced breast cancer.
• Randomized clinical trial comparing palbociclib plus letrozole against placebo plus letrozole as first-line therapy (ClinicalTrials.gov: NCT01740427).
• Evaluated outcomes across the overall population and subgroups following approximately 15 months of extended follow-up.
• Palbociclib plus letrozole sustained superior progression-free survival over placebo plus letrozole across the entire cohort and across all clinical subgroups, including patients with low disease burden or long disease-free intervals.
• The combination maintained a favorable safety profile and preserved patient quality of life over the extended observation period.