Monitoring of Hematologic, Cardiac, and Hepatic Function in Post-Menopausal Women with HR+/HER2− Metastatic Breast Cancer

Abstract

Introduction: In the treatment of metastatic breast cancer (mBC), regular monitoring is key in helping physicians to make informed clinical decisions, managing treatment side effects, and maintaining patients’ quality of life. Therefore, we investigated the monitoring frequency in post-menopausal women with HR+/HER2− mBC stratified by first-line regimen. Methods: Treatment monitoring was assessed using two complementary data sources: a medical chart review (chart review analysis) and a commercial claims database (claims analysis). Women with post-menopausal HR+/HER2− mBC who initiated first-line therapy for mBC were selected and classified under three cohorts, based on treatment received: cyclin-dependent kinase 4/6 (CDK4/6) inhibitor (i.e., palbociclib—the only CDK4/6 approved at the time of the study), endocrine therapy (ET), and chemotherapy. Frequency of monitoring [complete blood count (CBC), electrocardiogram (EKG), and liver function test (LFT)] and laboratory abnormalities detected during the first line of therapy were analyzed. Results: In the chart review analysis, 64 US oncologists abstracted medical information on 401 eligible patients, including 210 CDK4/6 users, 121 ET users, 51 chemotherapy users; 19 patients used other regimens. All patients had ≥ 1 CBC; between 8.3% (ET users) and 39.5% (CDK4/6 users) had ≥ 1 EKG; and over 98% of patients had ≥ 1 LFT across all three cohorts. Among monitored patients, 64.6% had a CBC abnormality, with anemia (39.9%), leukopenia (27.4%), and neutropenia (26.7%) being the most common. Abnormal EKG readings were detected in 8.4, 0.0%, and 7.7% of CDK4/6, ET, and chemotherapy users, respectively. LFT abnormalities were detected in 14.1–26.0% of CDK4/6 and chemotherapy users, respectively. Similar frequency of monitoring was observed in the claims analysis, with the exception of EKG monitoring, for which the proportion of patients tested was higher. Conclusion: Post-menopausal women with HR+/HER2− mBC receiving first-line therapy with CDK4/6, ET, or chemotherapy were regularly monitored regardless of the first-line regimen received. Funding: Novartis Pharmaceuticals Corporation.