An international clinical trial of the drug eculizumab shows a dramatic improvement in 80% of children and adults with a rare kidney disorder, aHUS (atypical hemolytic uremic syndrome). For some patients, the results are life-saving. The clinical trial is published June 6, 2013 in the New England Journal of Medicine.
“These results are exceptionally promising,” says Dr. Christoph Licht of The Hospital for Sick Children (SickKids), one of the study’s three principal investigators and co-lead authors. “We’ve learned that for many patients, treatment with this drug will mean leading a relatively normal life rather than facing eventual kidney failure and up to a sixty per cent risk of premature death.”
Up to one third of patients with aHUS recover spontaneously, but for those with sustained illness kidney transplantation may not be recommended as the transplanted kidney may also develop the disease.
Dr. Licht is a Staff Nephrologist and Associate Scientist in Cell Biology at SickKids and Associate Professor of Paediatrics at University of Toronto.
SickKids is a national and world leader in research and treatment of rare or ‘orphan’ diseases that affect children.
Renal failure from aHUS
The genetic, chronic, progressive condition causes tiny blood clots to form in the kidney’s intricate blood-cleansing vessels. “In many patients with this atypical, genetic or autoimmune form of hemolytic uremic syndrome, disease onset is often triggered by an infection or something that starts an immune response,” says Dr. Licht. A factor (or complement) in the immune system attacks healthy cells that line the kidney’s blood vessels. “When these cells are destroyed they trigger the formation of blood clots, causing renal failure. Some people also experience symptoms of blood clots forming in other organ systems,” he adds.
“We don’t fully understand why this autoimmune dysfunction hurts the kidney more than other organs. And as with most orphan diseases that have high mortality rates, the path to find effective treatment has been very tough,” Dr. Licht adds.
“That’s why seeing this continuous, steady improvement in kidney function is significant. We also found that the sooner patients received eculizumab, the more improvement they experienced,” he says. Some patients were able to discontinue dialysis.
New indication for established drug
Because aHUS is a rare disease – affecting about five in every million people, or an estimated 175 people in Canada – the Phase 2 trial required the efforts of 33 authors in seven countries in order to treat just 37 patients, aged 13 to 68. After weekly infusions for four weeks, participants received bi-weekly infusions for a total of 26 weeks.
The drug has been in use for about 15 years to treat another complement-mediated disorder characterized by the destruction of red blood cells. It recently received Health Canada approval to treat aHUS, and it is also approved for this use in the US and Europe.
The paper is titled “The Terminal Complement Inhibitor Eculizumab for Treatment of Atypical HUS.”
The Hospital for Sick Children (SickKids).