In the news this week, doctors have been given permission to give a British man with CJD a pioneering treatment. There is currently no treatment for this fatal condition. The treatment being offered to this patient is known as PRN100.
Creutzfeldt-Jakob disease (CJD) is a disorder that affects the brain and is fatal. It is caused by a protein, called a prion. These are misfolded proteins that are infectious, and they cause the misfolding of other proteins leading to their dysfunction. The majority of cases are spontaneous, whereas there are a few cases that have been inherited in an autosomal dominant fashion. Infection can occur through exposure to infected brain or spinal tissue as these proteins reside in the CNS. CJD has much greater occurrences in populations that practice cannibalism, this is known as kuru disease, found primarily amongst the Fore people in Papua New Guinea.
Accumulation of these misfolded proteins within the neural tissue eventually leads to neuronal degeneration and therefore the clinical onset of the disease. The classic symptoms of CJD are rapidly progressing dementia and myoclonus (spasmodic jerky contractions of muscles). Conformational change of proteins occurs which leads condensation centres of protein accumulation, plaque formation occurs which results in neuronal cell death progressing to spongiform encephalopathy. Initially there us a latency period which varies greatly but is on average about 10 years, but can be greater than 30years.
The PRN100 treatment that a patient in London is receiving is a manmade antibody therapy. Due to the nature of the disease causing misfolding of the body’s own proteins, the immune system doesn’t recognise these as foreign and therefore doesn’t produce antibodies to them in order to attack them. PRN100 is an antibody designed to attach tightly to normal proteins in order to prevent them from combining with the prions which would try and misfold the protein. Therefore, this antibody would stop the chain reaction of more proteins becoming misfolded however would not regress the disease. Despite the lack of knowledge about this treatment and the potential challenges it may face, researchers, patients and relatives are keen to start delivering this therapy to rapidly progressing cases due to the lack of alternative treatment available.