Atypical haemolytic uraemic syndrome in the eculizumab era: presentation, response to treatment and evaluation of an eculizumab withdrawal strategy

: The complement inhibitor, eculizumab, has revolutionised the management of atypical haemolytic uraemic syndrome (aHUS), although the optimum treatment duration is debated. Twenty-two cases of acute aHUS managed with eculizumab were retrospectively reviewed, including outcomes after eculizumab withdrawal. Although 41% had an associated complement genetic abnormality, mutation status did not affect severity of clinical presentation. Sixty-four percent required renal replacement acutely, with a high incidence of nephrotic range proteinuria (47%). Eculizumab followed a median of 6 days of plasma exchange. After a median duration of therapy of 11 weeks (range 1-227), haematological recovery was seen in 100%, while 81% achieved at least partial renal recovery (median increase in estimated glomerular filtration rate (eGFR) 49 ml/min/1·73 m2 ). At median duration of follow-up of 85 weeks (range 4-255), 54·5% had eGFR ≥ 60 ml/min/1·73 m2 , 27% had CKD, 14% were on dialysis, and 4·5% had died. Eculizumab was withdrawn in 59% (13/22) cases following complete haematological and renal recovery. Three of these 13 patients (23%) subsequently relapsed, with defined triggers in 2/3, but all made a full recovery with rapid resumption of eculizumab. There was a significant association between higher presenting creatinine and poorer renal outcomes. A strategy of eculizumab withdrawal in selected cases is both safe and cost effective.