LAUSR

Background: Human Epidermal Growth Factor Receptor 2 positive (HER2+) breast cancer (BC) represents approximately 15% of early stage BC cases and is associated with a more aggressive clinical phenotype and poor prognosis with respect to most BC. Over the last decade new HER2-targeted therapies have become available that have prolonged survival for both early stage and metastatic breast cancer (mBC). However, the cost impact of these therapies has not been fully assessed in recent years. Given the evidence for major clinical benefit, it is imperative that health systems evaluate new treatments to maximize the value of health care expenditures. This study evaluated healthcare costs among mBC patients treated with HER2-targeted therapy. Methods: A retrospective cohort study using the IQVIA Real-World Data Adjudicated Claims Database (1/1/2015-7/31/2019) was conducted. Adult (≥18-years) female patients who initiated HER2-targeted therapy with evidence of mBC diagnosis in the prior year were identified. The study index date was the initiation date of the HER2-targeted agent after which, patients were required to have ≥12 months of follow-up. Annual all-cause and BC-related healthcare costs per patient (2019 USD) were computed using payer-paid amounts in the first and second year following the index date. BC-related costs were defined as costs for claims with a primary diagnosis for BC (ICD-9-CM: 174.% or ICD-10-CM: C50.%) or BC-related treatment (surgery – mastectomy or lumpectomy, HER2-targeted therapy, chemotherapy, hormone therapy, immunotherapy, and radiation). Results: 708 mBC patients treated with HER2-targeted therapy were included with a mean age (SD) of 53.2 (10.2) years and mean follow-up of about 2 years. During the follow-up period, trastuzumab (96.5%) and pertuzumab (81.2%) were the most common HER2-targeted therapies used followed by ado-trastuzumab (15.4%), neratinib (6.3%), and lapatinib (5.3%). Additionally, patients received other treatments including chemotherapy (88.0%), hormone therapy (56.6%), and radiation therapy (57.6%). Of note, 40.3% of patients underwent surgery (mastectomy or lumpectomy) following evidence of metastasis. Following initiation of HER2-targeted therapy, mean annual costs per patient in Year 1 and Year 2 were $330,784 and $196,139, respectively. Correspondingly, BC-related costs in Year 1 and Year 2 were $255,273 and $144,978, respectively. HER2-targeted therapies accounted for 72% of BC-related costs in both Year 1 and 2. Surgery patients incurred $37,822 higher BC-related costs in Year 1 compared to non-surgery patients. However, in Year 2, the opposite was noted with non-surgery patients having $70,885 higher BC-related costs, mainly due to a differences in BC treatment rates in Year 2 for HER2 targeted drugs, other BC drugs and radiation. Conclusion: Total BC-related costs of mBC patients treated with HER2-targeted therapy is highest in the first year following treatment initiation, with the main cost driver being the cost of HER2-targeted therapy. While total costs decreased in the subsequent year, the cost of HER2 targeted therapy remained the dominant component. Results of this study highlight the significant economic burden of treating HER2+ mBC and also the need for therapies that limit disease progression. Page 1 of 1 Citation Format: Reshma Mahtani, Deepa Lalla, Nina Oestreicher, Augustina Ogbonnaya, Vishal Saundankar, Joanne Willey, Anna Coutinho, Kelly McCann. Healthcare costs for metastatic breast cancer patients treated with human epidermal growth factor receptor 2 targeted agents [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 PS9-54.