14 Real-World (RW) Treatment Patterns and Clinical Effectiveness of Palbociclib (PAL) Plus an Aromatase Inhibitor (AI) as First-Line Therapy in Advanced/ Metastatic Breast Cancer (A/MBC): Analysis From Syapse Learning Health Network

Jeanna Wallenta Law, MPH¹; Debanjali Mitra²; Henry Kaplan, MD³; Tamuno Alfred, PhD²; Adam Brufsky, MD, PhD⁴; Birol Emir, PhD²; Haley McCracken, BS¹; Xianchen Liu, MD, PhD²; Ronda Broome, MS¹; Chenan Zhang, PhD¹; Caroline DiCristo, PharmD²; Connie Chen, PharmD²

¹Syapse, United States

²Pfizer, Inc., United States

³Swedish Cancer Institute, Seattle, WA

⁴Comprehensive Breast Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, PA

Background

With nearly 6 years of prescribing experience since the US approval of palbociclib (PAL), there is now adequate follow-up to evaluate real-world (RW) effectiveness of PAL and aromatase inhibitor (AI) treatment. This retrospective, single-arm study evaluated RW treatment patterns and clinical outcomes of patients with hormone receptor–positive/HER2–negative (HR+/HER2–) advanced/metastatic breast cancer (a/mBC), who received PAL plus AI as first-line (1L) therapy in US practices.

Methods

The study used the Syapse Learning Health Network, a longitudinal database that collects cancer care data from the entirety of a patient’s journey from US health systems across 25 states, 457 hospitals, and among 1317 community oncologists. Death data were captured using multiple sources. Patients aged 18 years and older with HR+/HER2– a/mBC who initiated 1L PAL + AI were evaluated from February 2015 through July 2019, with 6 months or more of potential follow-up. Patients were followed from treatment initiation until data cutoff (February 2020), death, or loss of contact, whichever came first. All results were descriptively summarized. Median time to event rates were obtained using Kaplan-Meier estimates.

Results

The study included 242 patients (median age, 66 years; Table). Median duration of follow-up was 22.4 months. The most common reasons for treatment discontinuation were progressive disease (26%) and intolerance/toxicity (15%); 44% of patients remained on treatment at study cutoff. Among patients with a known dose adjustment (31%), mean time to adjustment was 167.4 days; median time was 55 days. Median time to treatment discontinuation and real-world progression-free survival (rwPFS) were 23.9 (95% CI, 17.6-28.5 months) and 31.7 months (95% CI, 26.5-50.3 months), respectively. Twelve- and 24-month overall survival (OS) rates were 90% (95% CI, 87%-94%) and 78% (95% CI, 72%-84%), respectively; 25.6% of patients died during the study.

TABLE

Conclusions

RW effectiveness outcomes in patients with HR+/HER2– a/mBC receiving 1L PAL + AI from the Syapse network of community oncologists complement randomized clinical trial data and other US electronic health record studies. This study is limited by a small sample size and limited follow-up.

Disclosures

Law is a Syapse employee; Mitra is an employee and has stock ownership at Pfizer Inc; Kaplan is a consultant for Syapse; Alfred is an employee and has stock ownership at Pfizer Inc; Brufsky has consulting fees from Pfizer Inc; Emir is an employee and has stock ownership at Pfizer Inc; McCracken is a Syapse employee; Liu is an employee and has stock ownership at Pfizer Inc; Broome is a Syapse employee; Zhang is a full-time Syapse employee; DiCristo has no disclosures; Chen is an employee and has stock ownership at Pfizer Inc.

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