Eculizumab is an antibody treatment for PNH. It works by blocking a specific part of the immune system – a protein called C5 – which causes the destruction of red blood cells in PNH. The drug was tested thoroughly in clinical trials, which showed that it was safe and worked well, and in 2007, eculizumab was given the green light to be used in Europe as a treatment for PNH.
In this study from 2013, Peter Hillmen and colleagues assessed the drug’s long-term safety in 195 patients who received the treatment continuously for up to five and a half years. The study confirmed earlier trials’ findings; that the drug is safe to take and gets to work quickly, preventing red blood cells from being broken down.
In addition, the treatment improved kidney function and greatly reduced the risk of developing blood clots (96% of the patients remained clot free). Eculizumab also reduced the need for blood transfusions. At the start of the treatment, nearly all of the patients depended on transfusions, but by the time the study finished, the vast majority (over 80%) no longer required them. Of those that did, the number of red blood cell units required, had decreased by half.
In summary, eculizumab improved the patients’ symptoms, decreased the risk of developing complications and boosted overall survival. Now, a patient with PNH who takes eculizumab can expect to live as long as a person who doesn’t have PNH. In the UK, eculizumab (also known as Soliris) is given intravenously as an infusion, once every two weeks on an ongoing basis.
Eculizumab reduces blood clots (2020)
Paroxysmal nocturnal haemoglobinuria (PNH) is a rare disorder, characterized by the breakdown of red blood cells and the formation of blood clots within vessels. The formation of blood clots within blood vessels can result in many complications including heart attacks, strokes and liver failure. The reason for the increased incidence of blood clot formation in PNH is still poorly understood. However, it is thought to be driven by the loss of a protein found on blood cell surfaces which normally protects them from the immune system. Without this protein the immune system starts to break down blood cells in the blood releasing harmful material that may trigger clot formation. Treatment with a drug called eculizumab, which dampens the immune response, has been shown to significantly reduce blood clot formation in PNH patients. In many cardiovascular diseases such has diabetes and heart attacks, patients have been found to have changes in how their blood clots form possibly giving them a predisposition to disease. Based on this our aim in this study was to investigate changes in clot formation and structure as a possible mechanism for increased blood clot formation in patients with PNH. This study explored the formation, structure and breakdown of blood clots in plasma samples from 82 patients from the National PNH Service in Leeds, UK. PNH patients who were not on any form of treatment were found to have increased levels of two clotting proteins, called fibrinogen and thrombin, in their blood. Increases in these proteins also led to clots forming faster with a subsequent clot structure that was harder to break down. PNH patients on eculizumab treatment were found to have decreased levels of fibrinogen and thrombin in their blood. This resulted in slower forming clots with an improved clot structure. As the length of time on eculizumab treatment increased the positive effects on clotting increased. This study suggests that PNH patients have a predisposition to increased blood clot formation due to increased fibrinogen and thrombin levels leading to faster clot formation. Treatment with eculizumab helps to reduce clot formation by reducing fibrinogen and thrombin levels and this has positive downstream effects on clotting.