Dwarfism Drug Brings Mixed Emotions for Little People, Parents

Chelley, Adelaide and Dave Martinka
Chelley and Dave Martinka with their daughter Adelaide at the LPA National Conference in San Diego in 2014. Source: Brooke Aliceon Photography via Bloomberg

An experimental drug to treat dwarfism by lengthening children’s bones is meeting skepticism from the leading U.S. group that represents little people, which questions giving kids a medication that might make them less little.

Parents like Chelley Martinka, whose daughter has the condition, achondroplasia, say they have no intention of giving their children injections of BioMarin Pharmaceutical Inc.’s BMN 111. That won’t change even if the drug lives up to the promise of its early trials, said Martinka, who blogs about her daughter’s condition at “A Is for Adelaide.”

“My daughter is incredibly smart, she’s funny, she is the most loving person I’ve ever met,” said Martinka, who doesn’t have achondroplasia. “I can’t ask for anything else. To do something superficial, to give her a couple of inches, it’s ridiculous.”

BioMarin is betting it can persuade parents to embrace the drug’s potential to add height and avert health issues that come with the genetic disorder. The medicine will be a hot topic at the annual meeting of Little People of America, which starts Friday in St. Louis.

Leaders in the organization are talking regularly with San Rafael, California-based BioMarin. They worry the drug is being presented as a way to address an “affliction.”

“Just because a person has achondroplasia doesn’t mean they are going to have health issues,” said Gary Arnold, the group’s president, who encourages new parents to get to know others in the community. “This drug might be right for some people, but we also think it’s important to get across the message that it’s not necessary to live a healthy and productive life.”

Gene Mutation

The average man with achondroplasia grows to a height of 131 centimeters, or 4 feet 4 inches, while the average woman with the condition reaches 4 feet 1 inch. The condition arises from a mutation in the FGFR3 gene, which produces a protein that inhibits the formation of bone from cartilage. The mutation makes the protein overly active, which researchers believe limits bone development.

BMN 111 is a man-made version of a natural peptide that can spur bone growth. BioMarin’s drug, also called vosoritide, boosted the speed of growth by as much as 50 percent in the first study of children with the condition, the company reported last month. That translated to almost an extra inch of height a year.

BioMarin shares jumped 12 percent the following day. The company estimates there are 24,000 children under age 18 in its potential patient population. If the drug is effective for children across that age range, that would create a market of as much as $1.8 billion a year, estimated Robyn Karnauskas, an analyst at Deutsche Bank, in a presentation to clients. Michael Yee, an analyst at RBC Capital Markets, estimates that BioMarin could charge $300,000 for the drug, which would be the company’s biggest product.

No Placebo

The study involved just 26 children with an average age of 7.8 years, with the 10 getting the highest dose seeing the most benefit. There was no placebo comparison, so the trial didn’t examine how they fared compared to children getting no treatment.

There’s no evidence so far that the therapy made the proportions of the children’s bodies more like an average person’s. And there’s no way to know if the accelerated growth would stop, a potential problem since other drugs tested to treat the condition have been difficult to control.

A final study of BMN 111 will probably involve 50 to 100 patients treated for six to 12 months, according to BioMarin. That may not be enough time to show if it helps children avoid serious health complications or if long-term use comes with side effects or potential harm.

Vosoritide may do more than just increase height, said Henry Fuchs, BioMarin’s chief medical officer. Kids who grow more normally could avoid some of the side effects of achondroplasia, such as a curved spine, he said.

Breathing Problems

The stunted growth can lead to a host of complications, including neurological and breathing problems, when the spinal cord, tonsils and other unaffected tissue grows faster than the surrounding bone, said Melita Irving, the lead investigator of BioMarin’s trial and a consultant in clinical genetics at the Guy’s and St. Thomas’ hospital system in London.

If it works, the drug could replace lengthy, painful and expensive surgeries to break and stretch bones. The process, which takes months, is currently the only option in a quest for longer limbs and better function.

“If it’s proven to be safe, I don’t think any average-height person with a baby is going to say no,” said Kristina Gray, the mother of a 4-year-old boy with achondroplasia in Warwickshire, England. “I see this as giving my son a better quality of life.”

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