The safety and efficacy of palbociclib in older patients with advanced breast cancer in a real-world setting

Aims: Palbociclib has been approved in combination with endocrine therapy (ET) for hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC), regardless of age. Even though ABC is one of the most prevalent cancers in older patients, very few patients ≥ 65 years old were included in pivotal trials. Therefore, the current study evaluated the safety and efficacy of palbociclib in “real-world” routine treatment of unselected older patients with HR+/HER2- ABC. Methods: Data were collected on patients > 70 years old who were treated with palbociclib plus ET for HR+/HER2- ABC in our institution. We analyzed safety data (CTCAE v4.0 criteria) and outcomes, such as progression-free survival (PFS) and overall survival (OS), as well as any associations between main geriatric characteristics and our results. Furthermore, we assessed safety at a national level by analyzing all palbociclib-related adverse events (AEs) reported in the French Pharmacovigilance Database (FPVD) during the same period. Results: From February 2016 to July 2019, 52 patients were identified with a median age of 80.9 years, of whom 88% presented an AE. The most common grade 3-4 AE was neutropenia (64%). Median PFS and OS were nine months and not reached, respectively. The FPVD reports 227 cases of palbociclib-related AEs, with older and younger patients sharing similar characteristics. Conclusion: Palbociclib is well tolerated in older patients with efficacy comparable to that in younger patients. However, the addition of palbociclib to ET should be evaluated individually in this older and frailer subgroup.