Complement inhibitor therapy in atypical hemolytic uremic syndrome (aHUS): evaluating the economic impact of introducing eculizumab biosimilars in Germany

Background Eculizumab, a humanized monoclonal antibody, inhibits activation of complement component C5. For patients with atypical hemolytic uremic syndrome, the introduction of eculizumab has markedly improved survival, restoring life expectancy close to that of the general population. The long-acting C5 complement inhibitor (CI) ravulizumab has since expanded treatment options, offering extended dosing intervals. In 2023, the first eculizumab biosimilars received market authorization. This study aims to evaluate the short-term economic impact of CIs from a German healthcare payer perspective. Methods An economic model with weekly cycles and a time horizon of one year was developed to assess treatment costs for eculizumab originator, eculizumab biosimilars, and ravulizumab in adult patients with atypical hemolytic uremic syndrome, based on a standard adult body weight of 77.7 kg. The analysis included direct drug acquisition costs calculated on a milligram basis, obtained from publicly available German price databases and outpatient reimbursement regulations, as well as preparation costs for infusions. Treatment costs were analyzed up to 52 weeks to reflect short-term and annual treatment periods. All costs are presented in euros (2025), and no discounting was performed. Results Milligram-based prices were estimated at €12.92 for eculizumab biosimilar, €17.87 for eculizumab originator, and €13.63 for ravulizumab. After 13 weeks, cumulative costs were €124,941 (biosimilar), €172,466 (originator), and €127,062 (ravulizumab). After 52 weeks, costs reached €421,439, €581,836, and €352,463, respectively. Conclusions At treatment initiation, the eculizumab biosimilar appears to be the most cost-efficient option among CIs in Germany, offering cost savings relative to both the originator and the long-acting agent. Sequential use of different CIs may therefore represent a cost-saving option.