Estimating the Product Lifecycle Value of Trastuzumab Based on Registry Data in Sweden

BACKGROUND AND OBJECTIVE: Trastuzumab was introduced in Sweden in 2000 for treatment of HER2-positive metastatic breast cancer (MBC) and later expanded to early breast cancer (EBC). The potential value of this innovative therapy was explored in economic evaluations; however, the extent to which these benefits were realised remains unknown. This study aims to estimate the lifecycle value of trastuzumab by combining randomised trial data with Swedish routine-care data. METHODS: Trastuzumab impact on costs and health outcomes was estimated with Markov models for MBC and EBC. Model inputs included progression/recurrence and breast cancer-related mortality data from international randomised clinical trials, and Sweden-specific non-breast cancer-related mortality, numbers treated, and costs and utilities based on data from National Registries and literature. Model predictions were validated by observed survival rates from the National Breast Cancer Registry. RESULTS: From 2000 to 2021, 3936 and 11,134 patients with HER2-positive MBC and EBC, respectively, were treated with trastuzumab, resulting in 25,844 life years and 13,436 per quality-adjusted life years (QALY) gained. Cost per QALY gained was lower in EBC (Swedish krona [SEK] 285,000/QALY) than MBC (SEK 554,000/QALY). The net-monetary value delivered (excluding drug costs) was SEK 13.714 billion, and society retained 62% of this. The modelled survival in trastuzumab-treated patients with EBC matched closely with actually observed survival in registry data. CONCLUSION: Trastuzumab provided substantial population-level health benefits for patients and society, with favourable cost effectiveness in MBC and EBC. There is some uncertainty around the magnitude of these benefits, mainly due to missing data on health outcomes and number of treated patients with MBC. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40261-023-01279-2.