Laboratory Testing Patterns in Patients With Breast Cancer Treated With CDK4/6 Inhibitors: A Multi-Country Electronic Health Record Study From the UK, Germany, and Japan
Author(s)
Elsie Horne, PhD1, Patrycja Pluta, DVM, PhD2, Amit Samani, MD, PhD1, Qianyi Zhang, MS3, Sascha van Boemmel-Wegmann, PhD2, Blythe Adamson, PhD, MPH3, Lockwood Taylor, PhD, MPH3.
1Flatiron Health UK, London, United Kingdom, 2Flatiron Health Germany, Berlin, Germany, 3Flatiron Health, New York, NY, USA.
1Flatiron Health UK, London, United Kingdom, 2Flatiron Health Germany, Berlin, Germany, 3Flatiron Health, New York, NY, USA.
OBJECTIVES: The safety profile of certain drugs warrants regular laboratory testing to monitor the development of adverse events, such as hepatotoxicity. Laboratory data is typically available as structured data in electronic health records (EHRs) and has the potential to be leveraged to study real-world drug safety. A precursor to such a study is to confirm that the tests are being performed and captured in the EHR. This study is a multi-country comparison of the rate of liver function tests (LFTs) in patients with breast cancer taking cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6is).
METHODS: This was a retrospective cohort study that used the UK, Germany, and Japan Flatiron Health Research Databases. The cohort comprised female patients with locally advanced or metastatic hormone receptor positive and human epidermal growth factor receptor 2 negative breast cancer who started a CDK4/6i on or after January 1, 2017. The cohort was further restricted to patients whose EHR contained at least one LFT in the 4 weeks before their first CDK4/6i dose. The testing rate was summarized across three consecutive 4-week periods following the first CDK4/6i dose (defined as the percentage of patients with a recorded LFT during the 4-week period).
RESULTS: The UK, Germany, and Japan cohorts comprised 147, 86, and 106 patients, respectively. Palbociclib was the commonest CDK4/6i in the UK and Germany (received by 62% and 78% of the cohorts, respectively), while abemaciclib was the commonest in Japan (66%). The LFT rate exceeded 90% in the UK and Japan during all three periods, while in Germany it reduced across weeks 1-4 (84%), 5-8 (72%), and 9-12 (57%).
CONCLUSIONS: This study identified high EHR-derived LFT rates in patients with breast cancer taking CDK4/6is. These findings demonstrate the feasibility of using EHR-derived laboratory data to monitor hepatotoxicity.
METHODS: This was a retrospective cohort study that used the UK, Germany, and Japan Flatiron Health Research Databases. The cohort comprised female patients with locally advanced or metastatic hormone receptor positive and human epidermal growth factor receptor 2 negative breast cancer who started a CDK4/6i on or after January 1, 2017. The cohort was further restricted to patients whose EHR contained at least one LFT in the 4 weeks before their first CDK4/6i dose. The testing rate was summarized across three consecutive 4-week periods following the first CDK4/6i dose (defined as the percentage of patients with a recorded LFT during the 4-week period).
RESULTS: The UK, Germany, and Japan cohorts comprised 147, 86, and 106 patients, respectively. Palbociclib was the commonest CDK4/6i in the UK and Germany (received by 62% and 78% of the cohorts, respectively), while abemaciclib was the commonest in Japan (66%). The LFT rate exceeded 90% in the UK and Japan during all three periods, while in Germany it reduced across weeks 1-4 (84%), 5-8 (72%), and 9-12 (57%).
CONCLUSIONS: This study identified high EHR-derived LFT rates in patients with breast cancer taking CDK4/6is. These findings demonstrate the feasibility of using EHR-derived laboratory data to monitor hepatotoxicity.
Conference/Value in Health Info
2025-11, ISPOR Europe 2025, Glasgow, Scotland
Value in Health, Volume 28, Issue S2
Code
SA59
Topic
Study Approaches
Disease
Oncology