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Isaac McFadyen, who was born with MPS VI, at home with his family in Campbellford, Ont. (Kevin Van Paassen/The Globe and Mail)
Isaac McFadyen, who was born with MPS VI, at home with his family in Campbellford, Ont. (Kevin Van Paassen/The Globe and Mail)

Hopes and hurdles in the fight for Issac and his rare disease Add to ...

Andrew McFadyen lives with the agony of knowing that a ground-breaking treatment for his son’s debilitating disease may be just out of reach.

His son Isaac was born with MPS VI, an extremely rare metabolic disorder. At age 2, Isaac was featured in a Globe and Mail series that led to the Ontario government’s decision to fund Naglazyme, the only available treatment for his disease, which costs an annual $300,000 to $1-million a patient.

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But despite receiving weekly injections of the drug, Isaac, now 8, is far from leading a normal life. He is more than a head shorter than other boys his age, and has stopped growing. His hands are clawing up and he is losing mobility in his spine, limbs and joints. He will soon be a candidate for corneal transplants and is at high risk for heart disease and a shortened life.

There is hope. Researchers at Mount Sinai Hospital in New York have come up with an experimental treatment for MPS VI. In a study published January in the online journal PLoS One, rats with the disease showed remarkable improvement in mobility and other indicators after taking pentosan polysulfate, an anti-inflammatory drug that costs about $7 a pill.

McFadyen helped fund the study as head of the Isaac Foundation, an organization he runs in addition to his job as a schoolteacher in Kingston, Ont. “We fully believe this treatment will work wonders,” he says.

But in the world of rare diseases, the battles never end.

Experimental treatments that work in rats are often ineffective in humans. Researchers do not know whether the anti-inflammatory drug would interfere with Naglazyme in children who depend on it to stay alive. Testing the drug in children with MPS VI would require an adequate number of patients to convince regulators that the treatment is effective, but only nine children in Canada have Isaac’s disease. To recruit enough patients, a human trial would require international co-operation and approval from a variety of health agencies and ethics boards.

The biggest hurdle, however, would be to convince a pharmaceutical company to make a multimillion-dollar investment in research that may have meagre financial return.

Nevertheless, McFadyen is convinced the drug-approval process can be streamlined if he can just get the pharmaceutical industry on board. He notes that pentosan polysulfate has already been proven safe in humans. Johnson & Johnson holds the patent for the drug under the brand name Elmiron, which was approved decades ago as a treatment for interstitial cystitis (an inflammation of the bladder).

McFadyen has spent the past six months lobbying Johnson & Johnson to fund clinical trials in patients with MPS VI. So far, the company has made no commitments. “They promote themselves as being humanitarian driven,” McFadyen says, “and here they are, sitting on a product that is having dramatic, earth-shattering results in the lab.”

Julian Raiman, a specialist in MPS diseases at the Hospital for Sick Children in Toronto, confirms the findings from the rat studies are promising.

He says the current treatment, Naglazyme (and other forms of enzyme replacement therapy), may decrease the rate of decline in many MPS patients but does not treat the inflammation of the musculoskeletal system associated with MPS disorders. The rat study suggests the anti-inflammatory drug may prove effective for various forms of MPS and other lysosomal storage diseases. The question, Raiman points out, is “can that be mirrored in humans?”

Only clinical trials can tell.

But Durhane Wong-Rieger, president of the Canadian Organization for Rare Disorders, says she doubts Johnson & Johnson “will ever put up money for this trial.”

Later this year, Canada will adopt a regulatory framework to spur new treatments for orphan diseases, she notes. But even so, it would take a multimillion-dollar investment and at least six years to have Elmiron approved for a new indication, she says. Meanwhile, the company’s patent on the drug is running out.

Johnson & Johnson declined an interview request but provided a statement: “A senior staff member in our research-and-development organization has assembled a team to fully evaluate this situation and determine if and how we can be helpful,” it says in part. The statement adds, “Unfortunately, we are not able to help in every situation.”

The company’s annual earnings dropped 27 per cent in 2011 to $9.7-billion, but 2012 saw that number climb to $10.9-billion.

Deb Purcell, whose eight-year-old son Trey has MPS II, says it would “unethical” for Johnson & Johnson not to fund a clinical trial. Purcell, who lives in Vancouver, says she has heard parents in the MPS community considering giving their children Elmiron despite the unknown risks. “There are a lot of desperate families out there.”

McFadyen says he fears that if Johnson & Johnson does not test Elmiron as a potential treatment for MPS, competing drug companies will reformulate the inexpensive oral medication as an injection drug that will hit the market many years from now, at an exorbitant price. It wouldn’t be the first time the pharmaceutical industry has profited from rare diseases, he adds.

“Everyone seems to forget that the lives of kids are hanging in the balance,” he says, “and no dollars can ever bring them back.”

A primer on MPS disorders

MPS VI is an extremely rare genetic disorder that affects an estimated 1,100 people in developed countries worldwide. People born with MPS VI (which stands for mucopolysaccharidosis VI) tend to have stunted growth, irregular facial features, restricted movement and breathing problems. Many require heart-valve surgery.

MPS VI shares similarities with other MPS disorders. MPS patients lack a specific enzyme needed to break down long chains of sugar carbohydrates, which build up in the body’s cells and damage multiple organs. One in 25,000 babies is born with an MPS disease.

The MPS disorders, in turn, are part of a larger group of nearly 50 lysosomal storage disorders. Together, LSDs are estimated to affect about 1 in 7,700 births.

 

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