Abstract PS14-15: Real world treatment patterns and healthcare resource utilization among HER2+ metastatic breast cancer patients with and without brain metastases: A retrospective cohort study
Authors: Ike Chiemeka , Schwartz Naomi , Surinach Andy , Liu Yutong , DeBusk Kendra , Walters Thomas 
Published: February 2021

Abstract
Background: Human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC) is associated with increased clinical and economic burden. Patients with brain metastases (BM) have significantly worse outcomes, however, limited data exist evaluating healthcare resource utilization (HCRU) among HER2+ MBC patients with BM. Objective: To describe treatment patterns and HCRU among HER2+ MBC patients with or without brain metastases who received HER2-targeted therapy using retrospective claims data. Methods: Data obtained from the IBM Watson HealthTM MarketScan commercial claims and Medicare Supplemental database from July 2012 to December 2018 were used to evaluate HER2+ MBC patients. We describe demographic and clinical characteristics, treatment patterns by line of therapy (LOT) by the presence or absence of BM, and HCRU. The first metastatic diagnosis date was the study initiation (index) date. HCRU outcomes per patient per year (PPPY) in the follow-up period after metastatic diagnosis were measured overall and by BM vs non-BM. These HCRU outcomes included inpatient (IP) services, total length of stay (LOS), emergency room (ER) services, and outpatient (OP) services. Results: A total of 4,509 patients were included. One-hundred and three (2.3%) patients had BM and 4,406 had no evidence of BM at index. However, 590 (13.1%) developed BM after study initiation. The mean age at index was 53.7 years. Median follow-up time was 23.2 months overall (22.1 months for patients with BM at index and 23.2 months for patients without BM at index). Median time on treatment (months) was 7.6, 7.2, and 6.2 for first line (1L), 2L, and 3L, respectively. Trastuzumab-based regimens were most used across all LOTs. Trastuzumab emtansine (T-DM1) use in 1L was 0.9% (2.4% in BM and 0.9% in non-BM patients). T-DM1 use increased in 2L (9.7%) and 3L (13.0%) and differed for BM vs non-BM patients in 2L (22.6% vs 7.7%) and 3L (25% vs 10.1%). Overall, lapatinib use ranged from 1.6% (1L) to 8.3% (3L). BM patients had a higher frequency of lapatinib use compared to non-BM patients (1L: 11.8% vs 1.2%; 2L: 20.5% vs 1.8%; 3L: 21.2% vs 5.1%). The mean number of IP services PPPY was 0.6 and higher for BM patients (1.2 vs 0.5). The mean total LOS PPPY was 2.7 days and BM patients had higher total LOS (8.6 vs 2.6 days) compared to non-BM patients. The average number of ER visits PPPY was 1.2 and BM patients had higher frequency of ER visits (2.5 vs 1.2). The mean number of OP services PPPY was 57.1; however, no obvious difference was observed between BM and non-BM patients (62.1 vs 56.9). Conclusions: Among HER2+ MBC patients, there is significantly higher HCRU among BM patients compared to patients without BM. This highlights the need for more effective systemic therapies that improve outcomes and reduce disease and healthcare system burden for HER2+ MBC patients, particularly those with BM.
Citation Format: Chiemeka Ike, Naomi Schwartz, Andy Surinach, Yutong Liu, Kendra DeBusk, Thomas Walters. Real world treatment patterns and healthcare resource utilization among HER2+ metastatic breast cancer patients with and without brain metastases: A retrospective cohort study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-15.