Multicenter retrospective study of tolerability and efficacy of palbociclib for metastatic breast cancer in older women

Palbociclib has become the standard of care for ER-positive, HER2-negative metastatic breast cancer (mBC), but real-world evidence in older women (aged ≥ 70 years) remains scarce. A multicenter retrospective study in The Netherlands evaluated tolerability and efficacy of any line palbociclib for ER+ HER2- mBC in older women. Grade 3 or 4 toxicity (primary endpoint) was seen in 54% of patients. There was no neutropenic fever of grade 5 toxicity. Dose reduction occurred in 50% of patients, 8% disontinued treatment due to toxicity, and 3% were hospitalized due to toxicity. First-line palbociclib was associated with median progression-free and overall survival of 12 and 32 months, respectively, while second-line palbociclib was associated with median PFS and OS of 12 months and 31 months, respectively. The authors conclude that palbociclib was generally well tolerated and was a valuable treatment option for ER+ HER2- mBC in older women.