Eculizumab treatment and discontinuation in pediatric patients with atypical hemolytic uremic syndrome: a multicentric retrospective study

Introduction: Eculizumab is effective treatment of pediatric atypical hemolytic uremic syndrome (aHUS). However, the optimal duration of treatment is not clearly defined. The aim of this study was to retrospectively analyze the outcome of pediatric patients with aHUS, who started eculizumab treatment but discontinued it during the follow-up period.

Methods: The clinical and laboratory findings of the pediatric patients with aHUS were recorded on a web-based, national registry system, known as the Turkish aHUS Registry. The study included 63 patients who had to have received more than four doses of eculizumab during the acute phase of the disease.

Results: The median age at diagnosis was 3.62 (IQR: 1.29-6.14) years. During the follow-up period, 39 patients continued to receive standard eculizumab treatment (standard treatment group, treatment every 2 weeks) while 24 received an extended dose of eculizumab at three-four-week intervals (non-standard treatment group). There was no significant difference between both groups in terms of clinical and laboratory parameters. Eculizumab treatment was discontinued in 18 patients (30.7%, F/M:11/7), and the median age of these patients at diagnosis and their median follow-up duration were 4.0 (IQR:2.7-10.2) and 4.2 (IQR:2.2-7) years respectively. The median eGFR at the last visit was 110 (84.7-146.1)ml/min/1.73 m². Fourteen patients remained in remission without any sign of the disease. Recurrence occurred in four (22.2%) patients, in which eculizumab was immediately started again and complete remission was achieved.

Conclusion: Eculizumab is a successful treatment option in pediatric patients with aHUS and it can be safely discontinued with close monitoring in a selected group of patients. In case of recurrence, eculizumab should be restarted immediately to achieve complete remission.