Rare aHUS after kidney transplant successfully treated with Soliris
Case report describes recovery after transplant-related complication
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A rare case of atypical hemolytic uremic syndrome (aHUS) developed after a kidney transplant in a young man and was successfully treated with Soliris (eculizumab), according to a case study.
“The occurrence of [aHUS] following [kidney] transplantation is extremely uncommon and associated with adverse outcomes, often resulting in early graft [transplanted organ] loss,” the researchers wrote. They added that “comprehensive pre-transplant evaluation is essential to identify potential aHUS risk factors,” and “timely diagnosis and early application of [Soliris] … are crucial.”
Understanding atypical hemolytic uremic syndrome
The case study, “Eculizumab Successfully Rescues Against de novo Atypical Hemolytic Uremic Syndrome Following Retransplantation,” was published in Transplantation Proceedings.
aHUS is caused by the abnormal activation of the complement cascade, part of the immune system. This process can damage the lining of blood vessels and cause clots to form in small vessels, particularly in the kidneys.
The disease is also characterized by hemolytic anemia — a condition in which red blood cells break apart — along with low levels of platelets, the blood cell fragments that help with clotting.
Many aHUS cases are associated with mutations in genes that regulate the complement cascade and may involve triggering events, such as infection, autoimmune disease, or certain medications. However, aHUS can also occur without a clearly identified genetic cause.
In this report, researchers in China described a young man who developed aHUS after each of two consecutive kidney transplants. The condition was ultimately controlled with Soliris, a therapy approved for aHUS that works by blocking abnormal complement activation.
First kidney transplant followed by signs of aHUS
A 22-year-old man developed kidney failure due to membranous nephropathy, an autoimmune condition in which the immune system mistakenly attacks the tiny filtering units (glomeruli) in the kidneys.
He underwent a kidney transplant in June 2022 and received immunosuppressive medications to prevent rejection. At discharge, his creatinine level, a marker of kidney function, was 3.4 mg/dL, above the typical range of 0.7-1.2 mg/dL.
One month later, he was urgently readmitted after blood tests showed worsening results. Hemoglobin — the protein that carries oxygen in red blood cells — had dropped further below normal, indicating worsening anemia, while creatinine had risen to 4.2 mg/dL, suggesting declining kidney function.
Doctors performed a biopsy of the transplanted kidney to check for rejection, which showed no evidence of T cell-mediated or antibody-mediated rejection. However, it did reveal signs of thrombotic microangiopathy (TMA) — a group of disorders, including aHUS, characterized by blood clots in small blood vessels.
His condition continued to worsen, with creatinine rising sharply to 6.5 mg/dL, while hemoglobin fell further and platelet counts dropped below normal levels. Although doctors suspected aHUS, Soliris was not yet available in China at that time — the therapy was approved in the country for aHUS in November 2022.
Despite intensive medical care, the transplanted kidney failed, and the man had to restart dialysis, a procedure that filters waste and excess fluid from the blood when the kidneys are failing.
Second transplant leads doctors to suspect aHUS again
He was placed back on the kidney transplant waiting list and underwent a second transplant in May 2024, nearly two years after the first transplant. Pre-transplant laboratory tests were generally stable. As with the first transplant, the procedure was successful, and he was prescribed immunosuppressive medications to prevent rejection.
However, he experienced a gradual decline in hemoglobin and platelet levels. Ultrasound imaging showed no signs of internal abdominal bleeding that could explain these findings.
Four days after surgery, lab results suddenly worsened, with a further drop in hemoglobin and platelets and a sharp rise in lactate dehydrogenase (LDH), a marker often associated with red blood cell breakdown and tissue damage. A biopsy of the transplanted kidney again showed signs of TMA, but no evidence of T cell–mediated or antibody-mediated rejection.
With these findings, doctors suspected that aHUS had returned, and this time, they started treatment with Soliris. He received an initial intravenous dose followed by weekly infusions over the next three weeks, along with platelet transfusions.
Soliris treatment leads to recovery and stable kidney function
Follow-up blood tests showed improvement in several key markers, including platelets, LDH, and creatinine, which fell to 2.7 mg/dL after treatment, indicating improving kidney function. Soliris was discontinued, and the man was discharged from the hospital 28 days after the second transplant surgery.
During a four-month follow-up, his kidney function remained stable, with creatinine levels ranging from 1.7 mg/dL to 2.2 mg/dL, and no signs of aHUS.
Genetic testing found no mutations in complement-related genes commonly associated with aHUS. However, researchers identified mutations in the AVIL gene, which plays an important role in maintaining the function of glomeruli. Mutations in this gene have been linked to steroid-resistant nephrotic syndrome, a severe early-onset kidney disease that does not respond well to corticosteroids.
“Post-transplant aHUS is a rare but serious complication leading to high graft loss risk,” the researchers wrote. “Timely diagnosis and early [Soliris] initiation are critical for successful graft salvage.”
