Small Study of BridgeBio's Dwarfism Drug Indicates Advantage over BioMarin

Pictured: female scientist peers into a microscope/courtesy of Getty Images

Pictured: female scientist peers into a microscope/Getty Images

BridgeBio is preparing to give BioMarin a run for its money. Monday, the Palo Alto, Calif.-based biopharma posted promising results from its small but highly anticipated Phase II study of infigratinib in achondroplasia.

Achondroplasia is the most common cause of dwarfism, occurring in anywhere from 1 in 15,000 to 1 in 40,000 people.

On the highest dose of infigratinib, 10 children showed an increased growth rate from a baseline of just over three cm per year at a six-month follow-up. Two more study participants had a mean change of +8.8 cm per year based on three months of data.

BridgeBio’s biggest competitor lies in its west coast neighbor, BioMarin. BioMarin’s Voxzogo (vosoritide) was the first drug approved for achondroplasia in November 2021. The company’s Phase III study showed a change of 1.57 cm/year over the placebo group, albeit across a larger group of 59 children.

The small study held significance for investors - BridgeBio’s stock soared as much as 73% Monday. BioMarin’s dropped by more than 5% upon the news release.

“Saying that the data is a win may be an understatement...If this data holds up in Phase III, it would likely and massively drive script preference, we believe, in BridgeBio's favor,” said Salim Syed of Mizuho Securities in a note to investors.

In addition to strong efficacy numbers, infigratinib is convenient – oral versus BioMarin’s injectible – with no serious adverse events or discontinuations. Voxzogo can cause injection site reactions in about 85%, vomiting in 27% and decreased blood pressure in 13%.

Both drugs target the genetic mutation that causes achondroplasia – FGFR3, a bone-regulating gene. In addition to short stature, the condition can also cause apnea, recurring ear infections, hydrocephalus and other health issues.

At this point, neither drug has any data proving it helps with these other complications, but the underlying science that demonstrated efficacy on bone growth suggests potential benefits over time.

“We believe it’s kind of a canary in the coal mine for your potential to impact the other long-term complications of achondroplasia,” Neil Kumar, Ph.D., CEO, BridgeBio, told STAT News.

After its launch, Voxzogo had a strong 2022, contributing around $169 million to BioMarin’s total $2.1 billion in revenue.

Based on the Phase II results, BridgeBio has already started enrolling participants for a pivotal Phase III study. Additional trials are expected in other FGFR3-mutation related conditions like hypochondroplasia and skeletal dysplasia related to achondoplasia.

Infigratinib gained accelerated approval from the FDA for FGFR-driven liver cancers, but the planned Phase III program was pulled after BridgeBio’s licensing partner announced plans to permanently discontinue distribution of the drug in October 2022.

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