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Growth Factor Shows Promise for Rare Syndrome Related to Autism

Researchers hope to expand trial using insulin-like growth factor to ease autism symptoms in children with Phelan-McDermid syndrome
November 18, 2014

Researchers at Neuroscience 2014 this week shared home videos of a child nearing the end of their 12-week pilot study using insulin-like growth factor (IGF-1) to relieve autism symptoms in in children with Phelan-McDermid syndrome. An emotional audience of scientists, parents and journalists watched the young girl eat her first ice cream cone and ride a scooter for the first time.

Phelan-McDermid syndrome is a rare genetic disorder with symptoms that typically include severe autistic behaviors. It results from a mutation that disables a gene known as SHANK3. Other, less-severe changes to this gene show up in around one percent of all children and adults with autism. So if IGF-1 continues to show promise for Phelan McDermid syndrome, future trials may include participants with other forms of autism.  

The researchers first reported the promising early results of their study at the International Meeting of Autism Research, in May. (Read the story here.) At that time, nine children had completed the placebo-controlled study, led by researchers at New York City’s Seaver Autism Center. Each child received either IGF-1 or a dummy treatment for 12 weeks. After a four-week “wash out” period, the two groups switched. Neither the researchers nor the children’s families knew when each child was receiving the placebo or drug until after he or she completed all behavior assessments.

Overall, IGF-1 produced significant improvements in social behavior, the researchers report. It also produced dramatic reductions in repetitive behavior in some of the children, including the child in the video.

High expense
Now the researchers are hoping to expand their trial beyond the 18 children in the pilot study being funded by the National Institutes of Health. The stumbling block: IGF-1 treatment costs more than $1,000 per week per child. The investigators have approached the drug’s sole maker, AMGEN, for discounted or free supplies.

Safety concerns
Earlier studies with animal models of Phelan- McDermid syndrome suggest that IGF-1 eases autism symptoms by improving communication between brain cells.

However, there are safety concerns around the drug’s long-term use. IGF-1 is a growth hormone. Indeed, it’s an FDA-approved treatment for dwarfism in children. As such, it may not be safe to use long term after a person’s bones have stopped growing.

Animal studies suggest mechanism
“This study exemplifies the genetic approach to developing treatments for autism,” comments Paul Wang, Autism Speaks head of medical research. (Autism Speaks was not involved in the study.) “By using animal models of single-gene disorders such as Phelan McDermid syndrome, researchers have advanced our understanding of problems on the molecular, cellular and brain-circuit level. Now we’re at the stage of seeing whether the insights gained through animal studies can be safely and effectively translated to people.”

“It’s been a bumpy road so far,” Dr. Wang says, referring to the disappointing results of early clinical trials of drugs for Fragile X syndrome. Fragile X is another autism-related disorder caused by a single gene mutation. “The results in this treatment study for Phelan-McDermid are very hopeful,” he adds. “However, they need to be extended far beyond this small group of children.”

Read more coverage of autism research at Neuroscience 2014 here.

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