What is spinal muscular atrophy and why does it require an Dh8m treatment?

Astha Muthoo, 35, left her career and job to take care full-time of Arya, 6, who has spinal muscular atrophy, in Abu Dhabi. Khushnum Bhandari / The National

Spinal muscular atrophy (SMA) is a debilitating condition that affects around one in every 10,000 children.

Zolgensma, the most effective treatment, is also the world’s most expensive drug.

A single one-time infusion of the drug costs Dh8 million.

But why does it cost so much?

The National explains.

What is SMA?

SMA is a hereditary disease caused by a missing or faulty gene that the body requires to make a protein essential for motor neuron cell survival.

Without sufficient levels of the protein, the motor neurons - which are nerve cells in the brain stem and spinal cord that control activities such as speaking, walking, breathing, and swallowing - die, leading to muscle weakness and atrophy.

There are four types of the condition.

Type 1 is the most severe and many children with it do not live past the age of two. In July, The National reported on the case of three-month-old Malak Al Alami, who received Zolgensma after winning a global “lottery” run by the medicine’s manufacturer, Novartis. It is allocating up to 100 doses at no charge this year and has appointed a third party to select recipients every two weeks.

Children with Type 2 may sit without support, but cannot walk on their own. Symptoms typically appear between six and 18 months. Depending on the severity of their symptoms, children with this type may live a normal life span.

Type 3 is a milder form of the disease and resembles muscular dystrophy. Children are usually able to walk with difficulty and some eventually need a wheelchair. Symptoms usually appear around 18 months or in early childhood. They usually have a normal life expectancy.

Type 4 is very rare. It starts in young adulthood and results in mild motor impairment.

How does the treatment work and why is it so expensive?

Zolgensma is the only therapy designed to directly address the genetic root cause of the condition. It does this by replacing the function of the missing or nonworking gene, which is critical in making a protein essential to motor neuron cell survival.

It works by using a harmless, genetically engineered virus that travels around the body to help restore some of the protein missing as a result of the condition.

It is extremely effective, but hugely expensive because its market is very small and it required a lot of research to develop it, Dr Sushil Garg, a consultant neurologist at NMC Royal Hospital in Dubai, told The National.

“These therapies are extraordinarily expensive as it is first of its kind gene modifying therapy, approved for rare neuromuscular disorders,” said Dr Garg.

“Any medicine which is for gene modifying or work on [the] immune system has to undergo a lot of research and trials and approval processes, hence is pretty expensive.”

However, it currently is only used in children under two, but that may change in time.

New trial

Novartis launched a trial earlier this year to evaluate the safety and efficacy of the drug in children with SMA weighing between 8.5kg and 21kg.

The results will supplement emerging real-world evidence and use of the therapy in the European Union and Canada, where regulators have approved the drug for use in babies and young children up to 21kg.

Abu Dhabi residents Rahul Pathak, 37 and his wife Astha Muthoo, 35, hope it will help their six-year-old daughter, Arya Pathak, who suffers from the condition. The National covered her plight earlier this week.

The disease has forced her to spend weeks at a time in intensive care. Even a common cold can take a heavy toll on her weakened body.

Her parents cannot legally fundraise to help cover the cost of the drug, but donors can pay money directly to hospitals to help with medical bills.