Long-Term Therapy with Eculizumab Biosimilar in Patients with Atypical Haemolytic Uraemic Syndrome: Outcomes of a Prospective Observational Study.

Background: The objective of a multicentre, prospective, observational study of an eculizumab biosimilar (Elizaria®) was to analyse the efficacy and safety of long-term complement inhibitor therapy in patients with atypical haemolytic uraemic syndrome (aHUS).

Materials and methods: The study included 50 patients aged 1-55 years, with 42% of them under the age of 18. The patients received the eculizumab biosimilar in routine clinical practice within 56 weeks; 19 patients (38%) had been treated with eculizumab prior to enrolment, whereas 31 patients (62%) were naive to complement inhibitors.

Results: By the end of the study, an increase in platelet count of 39.48 ± 21.7 × 109/L and 33.61 ± 24.06 × 109/L was reported in treatment-naive and treatment-experienced patients, respectively. By the end of the study, 96% of treatment-experienced patients and 100% of treatment-naive patients had normal platelet counts. The mean LDH activity did not change significantly, with levels of 253.84 ± 122.22 U/L registered at screening and 245.24 ± 93.52 U/L at the end of the study. In total, 39 patients (77.6%) at week 21 and 40 patients (80%) at week 52 had no thrombotic microangiopathy (TMA) events. During the study, the proportion of patients with a complete TMA response increased significantly, rising to 8% (p = 0.046). The proportion of patients with an estimated glomerular filtration rate improvement of 15 mL/min/1.73 m2 and more at week 52 was 12%. During the safety assessment, 63 adverse events not related to the investigational medicinal product were reported.

Conclusion: Long-term complement inhibitor therapy with the eculizumab biosimilar in patients with aHUS has demonstrated a stable effect, a favourable safety profile, and low immunogenicity.