OBJECTIVES : The Ibrance Real World Insights (IRIS) study collected data from patients with hormone receptor-positive (HR+), human epidermal growth factor 2-negative (HER2-) advanced breast cancer (ABC) receiving palbociclib combination therapy in real-world settings. We describe treatment patterns and outcomes for the overall cohort and patient subgroups using pooled IRIS data.

METHODS : IRIS was a multinational, retrospective cohort study that collected data from 13 countries (Argentina, Belgium, Canada, France, Germany, Italy, Japan, Netherlands, Portugal, Spain, Switzerland, United Kingdom, United States) in a standardized approach and included patients with HR+/HER2- ABC receiving palbociclib combined with aromatase inhibitor (P+AI) or fulvestrant (P+F). Clinical outcomes (progression free rate [PFR], survival rate [SR]) were estimated via Kaplan-Meier analyses. Patient characteristics and treatment patterns were summarized. Subgroup analyses were conducted based on patient characteristics, including line of therapy (first-line [1L], second-line or later [≥2L]), age, performance status (ECOG), and metastases site.

RESULTS : In total, 2954 patients receiving P+AI/F were included (mean age 63.3). Overall, 59.2% and 40.8% of patients received P+AI and P+F, respectively. Most patients had an ECOG at palbociclib initiation of 0 or 1 (P+AI: 86.1%; P+F: 85.8%). Most patients initiated palbociclib on 125mg/day (P+AI: 88.0%; P+F: 85.0%), of which, dose reductions were observed in 18.5% and 14.8% of P+AI and P+F groups, respectively.

Median follow-up from P+AI and P+F initiation was 10.0 and 7.4 months, respectively. The 12-month PFR was 87.5% for P+AI groups (88.5% 1L; 73.9% ≥2L) and 79.2% for P+F (83.3% 1L; 76.2% ≥2L). Twelve-month SR were 96.4% for P+AI (96.8% 1L; 91.5% ≥2L) and 95.5% for P+F groups (96.7% 1L; 94.7% ≥2L). PFR and SR outcomes were comparable across most subgroups.

CONCLUSIONS : This study represents the largest multinational assessment of real-world treatment patterns and outcomes associated with palbociclib. Findings were consistent across relevant subgroups and previously reported country-specific IRIS studies.