Real-world treatment of patients with palbociclib for HR+/HER2-advanced/metastatic breast cancer: the Europe IRIS study

Aim: To report the Europe Ibrance Real World Insights study findings. Methods: Physicians abstracted demographic/clinical characteristics, treatment and outcomes data for women with HR+/HER2- locally advanced breast cancer (ABC) or metastatic breast cancer (MBC) receiving palbociclib + aromatase inhibitor (AI) or palbociclib + fulvestrant. Kaplan-Meier analysis estimated progression-free rates (PFRs) and survival rates (SRs). Results: 238 physicians abstracted data for 1723 patients. For patients (>90%) initiating at 125 mg/day, dose was reduced in 18.9% of palbociclib + AI and 12.3% of palbociclib + fulvestrant patients. At 12 months, PFR for palbociclib + AI was 88.1%, and SR was 97.3%; PFR for palbociclib + fulvestrant was 79.8%, and SR was 97.5%. Conclusion: Low dose-reduction rates and favorable PFRs and SRs suggest that palbociclib + AI/fulvestrant is well tolerated and effective for HR+/HER2- ABC/MBC in real-world clinical practice. Lay abstract: We describe findings of the Europe Ibrance Real World Insights study. Patients were women with a common type of breast cancer that had worsened but not spread or that had spread. Doctors collected medical information about the women and looked at their progress while on treatment. The treatment was either palbociclib + an aromatase inhibitor or palbociclib + fulvestrant. Two hundred thirty-eight doctors collected information on 1723 women. More than 90% of women started this treatment at a dose of 125 mg/day; the dose was reduced for fewer than 20% of women. At 12 months, more than 80% of women survived without their breast cancer worsening, and more than 97% of women survived. These good results suggest that this treatment is safe and effective for women with breast cancer that had worsened but not spread or that had spread.