Experimental Pill Shows Promise for Achondroplasia Treatment

A new clinical trial is showing promising results for children living with achondroplasia, the most common genetic form of dwarfism. The Phase 3 PROPEL 3 study tested an investigational oral medication called infigratinib and found it significantly improved growth and may also improve body proportionality in children with the condition.

The study was led by researchers including investigators from the Murdoch Children’s Research Institute and sponsored by BridgeBio Pharma. Results suggest the medication could become an important new treatment option if approved by regulators such as the U.S. Food and Drug Administration.

"Achondroplasia is a genetic condition driven by FGFR3 that affects more than stature alone, with consequences on physical functioning and independence that can impact widely over a person’s lifetime,” said Ravi Savarirayan, M.D., Ph.D., of Murdoch Children’s Research Institute in Melbourne, Australia, and global lead investigator for PROPEL 3. “Infigratinib is the first oral therapy designed to target FGFR3 and directly address the underlying cause of achondroplasia. In the broadest age range studied to date, oral infigratinib has demonstrated the highest and most significant improvement in annualized growth velocity, along with the first statistically significant improvement in body proportionality, in children aged 3 to 8 years, reported for any therapy approved or in development for this condition.”

What is achondroplasia?

Achondroplasia is a genetic condition caused by changes in a gene called FGFR3. It affects bone growth and leads to disproportionate short stature. While height differences are a major feature, the condition can also affect overall health. People with achondroplasia may face challenges such as sleep apnea, spine problems, and joint issues that can affect mobility and independence.

Investigators continue working to develop treatments that address not only growth but also broader physical function and quality of life.

What did the study test?

The PROPEL 3 trial studied children ages 3 to younger than 18 who still had open growth plates, meaning their bones were still growing. Participants were randomly assigned to receive either oral infigratinib or a placebo for one year. Neither the participants nor the researchers knew who received which treatment until the study ended.

What were the key results?

Improved growth rate

Children taking infigratinib grew faster than those taking placebo. On average, children receiving the medication grew about 2 centimeters more per year than children who did not receive the drug. Researchers consider this a meaningful improvement in growth velocity.

The study also found that children taking infigratinib reached the highest average growth rate ever reported in a randomized achondroplasia trial.

Improved height compared with typical achondroplasia growth patterns

Investigators also measured height changes compared with expected growth patterns in children with achondroplasia. Children taking infigratinib showed significant improvement, meaning they grew closer to typical height expectations within the achondroplasia population.

Potential improvement in body proportionality

In younger children (under age 8), the medication showed the first statistically significant improvement in body proportionality in a randomized trial for achondroplasia. This means it may help balance the ratio between upper and lower body growth, which may affect physical function. Researchers say this finding is especially important because families often identify body proportion and mobility as meaningful treatment goals.

Advocacy leaders, including representatives from Little People of America, noted that proportional growth could influence independence and daily functioning, though more research is still needed to understand long-term impact.

Was the treatment safe?

Researchers reported that infigratinib was generally well tolerated.

Key safety findings included the following:

1. No participants stopped treatment due to side effects
2. No serious side effects linked to the medication
3. A small number of children developed mild, temporary increases in phosphate levels in the blood, which did not require treatment changes
4. No eye-related complications or side effects commonly seen with similar drugs
5. No injection-related side effects, since the medication is taken orally

What happens next?

Because of these results, BridgeBio plans to submit applications for approval in the United States and internationally during the second half of 2026. The medication has already received special regulatory designations, including Breakthrough Therapy status from the U.S. Food and Drug Administration (FDA), which may help speed development and review.

Researchers are also studying the medication in infants and toddlers and expanding studies into a related condition called hypochondroplasia.

Why this matters for families

If approved, infigratinib could become the first oral treatment option for achondroplasia. Having an oral medication may provide families with more flexibility and choice when considering treatment options. Researchers say continued studies will help determine how improvements in growth and body proportions may affect long-term health and daily life.

“There remains a significant unmet need for therapeutic options that are effective, practical, and less invasive for children living with achondroplasia,” noted Daniela Rogoff, M.D., chief medical officer, Skeletal Dysplasia of BridgeBio. “These results represent meaningful progress for those who have been waiting for a better approach, and we look forward to advancing this program toward global submissions.”