First medicine to treat rare Morquio A syndrome goes on sale
A new enzyme replacement therapy, elosulfase alfa, has been launched for a rare and debilitating genetic disease known as Morquio A syndrome.
Morquio A syndrome sufferers lack an enzyme that breaks down glycosaminoglycans (GAGs), leading to the harmful build-up of partially digested GAGs in cells, leading to tissue and organ dysfunction.
Elosulfase alfa — a recombinant form of the missing enzyme human N-acetylgalactosamine-6-sulfatase — breaks down the accumulated GAGs, although any damage already wrought cannot be undone by the treatment.
In the UK, 37 patients took part in phase III/IV clinical trials of the drug. “These patients say they feel the medicine is making a big difference to their lives, particularly to their respiratory problems and it has improved their endurance and pain,” says Christine Lavery, chief executive of The Society for Mucopolysacchride Diseases.
At birth, babies appear healthy but gradually become more disabled and often do not live beyond their twenties or thirties. Symptoms include short stature and changes to the skeleton that eventually prevent people from walking. “If patients receive the treatment early enough, it is hoped that this will prevent some of the symptoms developing,” says Lavery.
In a phase III clinical trial, it was found that patients receiving elosulfase alfa could walk an average of 22.5 metres further in 6 minutes, compared with placebo (95 per cent confidence interval, 4.0–40.9; P=0.0174).
Biomarin, the company that manufactures elosulfase alfa, says the drug costs UK£198,000 per patient each year.
In the UK, only 105 people have the syndrome and those who took part in the trial will be able to continue to receive the medicine until a decision is made on whether elosulfase alfa will be funded by the NHS, says Lavery.
Enzyme replacement therapies already exist for other lysosomal storage diseases, with drugs for type I, II and VI mucopolysaccharidosis priced similarly to elosulfase alfa; all are available on the NHS.
A decision to make elosulfase alfa available on the NHS is not expected until the end of 2015. “We are urging NHS England’s Clinical Priorities Advisory Group to make an urgent interim decision, in which case a decision could be made as early as July this year.”
Action: Replaces missing enzyme N-acetylgalactosamine-6-sulfatase.
Dose:2mg/kg of body weight administered once a week. The total volume shouldbe administered over approximately four hours. Patients should receive antihistamines with or without antipyretic, 30 to 60 minutes prior to infusion, because of the potential for hypersensitivity reactions.
Legal category: POM.
NHS list price: £198,000 per year.
Citation: The Pharmaceutical Journal DOI: 10.1211/PJ.2014.11138313
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