Publication-only abstracts (abstract number preceded by an "e"), published in conjunction with the 2019 ASCO Annual Meeting but not presented at the Meeting, can be found online only.
Real-world effectiveness of palbociclib in combination with an aromatase inhibitor as first-line therapy in metastatic breast cancer.
2019 ASCO Annual Meeting
J Clin Oncol 37, 2019 (suppl; abstr e12541)
Author(s): Xianchen Liu, Jack Mardekian, Lynn McRoy; Pfizer Inc, New York, NY
Background: Palbociclib in combination with an aromatase inhibitor (AI) was approved as initial endocrine therapy for patients with HR+/HER2– metastatic/advanced breast cancer (mBC) in February 2015. Evidence of real world outcomes for the combination to date has been limited by small sample size and short follow-up. This study describes patient characteristics and effectiveness of palbociclib + AI as first-line therapy in a large cohort of mBC patients in US clinical practice. Methods: Utilizing Flatiron Health’s longitudinal database, a retrospective cohort study was conducted to evaluate patients with HR+/HER2– mBC who started palbociclib + AI as first-line therapy between February 3, 2015 and August, 31, 2018. Patients were evaluated retrospectively from start of palbociclib + AI therapy on or after February 3, 2015 to November 30, 2018, death, or last visit in the database, whichever came first. Real-world progression free survival (rwPFS) was defined as months from start of palbociclib + AI therapy to death or disease progression based on clinical assessment or evidence by radiographic scan/tissue biopsy. Kaplan-Meier methods were used to estimate survival proportions in overall survival (OS) and rwPFS. Results: Of 878 who met the criteria, 66.9% were white, mean age was 65.2 years, 50.8% had visceral disease (liver and/or lung involvement), and 94% were treated in community practice. Patients were followed up to 46 months. Median rwPFS was 21.9 months (95% CI = 20.1 – 28.2). At 3 years of follow-up, OS rate was 91.9%. For additional outcomes, see Table. Conclusions: These findings from the largest cohort yet evaluated for real world effectiveness confirm the effectiveness of palbociclib + AI in routine clinical practice as a standard of care for first line treatment of HR+/HER2- mBC.
|Number of metastatic sites ≥ 3||29.2|
|rwPFS rate at 6 months||82.5|
|rwPFS rate at 12 months||69.1|
|rwPFS rate at 18 months||57.7|
|rwPFS rate at 24 months||48.2|
|OS rate at 12 months||95.4|
|OS rate at 24 months||91.9|
|OS rate at 36 months||91.9|