Eculizumab for paediatric patients with atypical haemolytic uraemic syndrome: full dataset analysis of post-marketing surveillance in Japan

Background Eculizumab was approved for atypical haemolytic uraemic syndrome (aHUS) in Japan in 2013. Post-marketing surveillance (PMS) was mandated by regulatory authorities to assess the safety and effectiveness of eculizumab in patients with aHUS in a real-world setting. Methods Paediatric patients in the PMS cohort who were Escherichia coli HUS, thrombotic thrombocytopaenic purpura and secondary thrombotic microangiopathy (TMA)] were included in the effectiveness and safety analysis. Clinical endpoints of effectiveness [complete TMA response, TMA event-free status, platelet (PLT) count and lactate dehydrogenase (LDH) normalization, serum creatinine (sCr) decrease and estimated glomerular filtration rate (eGFR) improvement] were analysed in patients treated with at least one dose of eculizumab. Serious adverse events (SAEs) were also evaluated. Results A total of 40 paediatric patients (median age 5 years) were included. The median eculizumab treatment duration was 66 weeks. PLT count, LDH and eGFR significantly improved at 10 days post-treatment. Complete TMA response, haematologic normalization, sCr decrease, eGFR improvement and TMA event-free status were achieved by 73.3%, 73.3%, 70.0%, 78.3% and 77.5% of patients, respectively. Discontinuation criteria were met by 18 patients: 13 patients maintained treatment discontinuation at the end of observation and 5 patients, including 1 patient with aHUS relapse, continued the treatment but extended the treatment interval. During eculizumab treatment, 59 SAEs (0.66/person-year) were reported. Although four deaths were reported, none of them were related to eculizumab. Conclusion Eculizumab was well tolerated and effective for paediatric patients with aHUS in the real-world setting in Japan.