Pfizer has halted the trial of a drug for a rare muscle-wasting disease after a child died suddenly.
The boy, who was between two and four years old, went into cardiac arrest after receiving the unique gene therapy last year.
Pfizer has not determined exactly what happened or whether the death was caused by the treatment, called fordadistrogene movaparvovec.
The New York pharmaceutical giant said the pause would allow it to investigate the death “while protecting the safety of participants, which is our top priority.”
Pfizer has stopped trial of a drug for a rare muscle-wasting disease after a child died suddenly (stock)
The victim was part of a mid-stage study that enrolled children ages two to four with Duchenne muscular dystrophy.
This rare disease mainly affects children (approximately one in every 3,500 male births) and patients do not usually live more than 25 years.
There were three serious adverse events during the study, but all children recovered within two weeks.
Pfizer has suspended administration of the same gene therapy in a separate late-stage study that enrolled children as young as eight years old.
That study compared whether the drug could slow the progression of the disease compared to a placebo.
If the trials went well, it was poised to become one of the most expensive drugs of all time.
A competing gene therapy from Sarepta Therapeutics Inc. gained accelerated approval from the FDA last year, becoming the only approved treatment for children with DMD.
A single dose costs around $3 million.
DMD is caused by a genetic mutation that means the body does not produce enough of a protein called dystrophin, which maintains muscle strength.
Without it, the muscles gradually deteriorate, causing problems with walking, sitting and talking and eventually affecting the muscles surrounding the lungs and heart.
By the age of 11, most patients usually require a wheelchair.
Pfizer’s drug works by introducing a shortened but functional dystrophin protein directly into patients’ muscle cells, slowing their breakdown.
It is administered through a single infusion.
Historically, the only medications used to treat DMD were steroids such as prednisone or deflazacort.
They reduce inflammation (a major problem in Duchenne), which slows the decline in muscle strength and mobility and may delay heart and lung complications.
But these can cause serious side effects, such as weight gain, delayed growth, delayed puberty, and reduced bone density, which can increase the risk of fractures.
