Late Onset Thrombotic Microangiopathy in Kidney Transplants; Poor Outcome Despite Eculizumab Treatment

Atypical hemolytic uremic syndrome (aHUS) is a rare cause of end stage kidney disease (ESKD) associated with a high rate of recurrence in kidney transplants causing a post-transplant thrombotic microangiopathy (TMA). Prophylactic eculizumab can prevent disease recurrence in select patients. Treating at the time of post-transplant TMA occurrence is the only option if the diagnosis of aHUS is not established pre-transplant. We report our experience of using eculizumab at the point of post-transplant TMA in those with a diagnosis or suspicion of aHUS. We conducted a case note review of 26 patients treated with eculizumab for post-transplant TMA. Screening for complement pathway defects included testing for variants in genes of the complement pathway and anti-factor H autoantibodies. 34.6% of recipients had an identified complement pathway defect. Median time to presentation with post-transplant TMA was 8.4 months. Death-censored graft survival 12 months after starting eculizumab was 68% for the cohort and was worse in those presenting >12 months post-transplant where this figure was 42.9%. The outcome is poor despite eculizumab treatment for those presenting >12 months after transplantation with TMA.