2 The condition
2.1 Familial chylomicronaemia syndrome (FCS) is a rare genetic metabolic disorder of lipid metabolism caused by homozygous mutations in the lipoprotein lipase gene. It is characterised by high levels of triglycerides in the plasma and a build-up of chylomicrons (the lipoprotein particles responsible for transporting dietary fat from the intestine to the rest of the body). Symptoms include repeated episodes of severe abdominal pain, unpredictable and recurrent episodes of acute pancreatitis, liver and spleen enlargement, and fatigue. Acute pancreatitis is a life-threatening condition for which intensive care may be needed. Repeated attacks of acute pancreatitis may lead to chronic pancreatitis. Diabetes can develop as a result of pancreatitis and often makes FCS more difficult to manage.
2.2 Current treatment options for people with FCS are limited. To keep plasma triglyceride levels low, management consists of severely restricting dietary fat intake (usually to between 10 g and 20 g daily, about a quarter of the normal daily intake suggested for an adult) and consuming no alcohol. People with the condition may take several drugs to control pain and other symptoms of FCS, including corticosteroids, analgesics, anxiolytics, antidepressants, diabetes treatments and antithrombotic drugs. People on a fat-restricted diet need supplements of essential fatty acids (linoleic and alpha linolenic acids) and fat-soluble vitamins (vitamins A, D, E and K). In addition, treatments for hypercholesterolaemia (such as fibrates, nicotinic acids and statins) may be prescribed but are of limited value. The strict dietary regimen is highly restrictive and often challenging for people with the condition and their families. Also, people often still have high triglyceride levels even when the diet is closely followed.
2.3 The prevalence of FCS is estimated to be 1 to 2 per million people, which equates to about 55 to 110 people in England. At the time of the evidence submission, there were thought to be around 80 to 100 people with FCS eligible for treatment with volanesorsen in the UK.
2.4 Treatment with volanesorsen has been provided since March 2018 under an Early Access to Medicines Scheme at several specialist centres. The company explained that, at the time of evaluation, 20 people were having volanesorsen (with treatment duration ranging from 1 to 15 months). A further 5 people have been identified to start treatment.