BioMarin Vosoritide sNDA: Expanding Voxzogo to Children Under 5

BioMarin Pharmaceuticals (BMRN) closed at $59.99 with a market cap of $11.7 billion. The company has filed a supplemental NDA to expand the label for Voxzogo (vosoritide) to children under 5 with achondroplasia, the most common form of dwarfism. The PDUFA date is February 28, 2027.

What Voxzogo does

Voxzogo is a C-type natriuretic peptide (CNP) analog that targets the FGFR3 pathway. In achondroplasia, a mutation in the FGFR3 gene causes overactive signaling that suppresses bone growth. Voxzogo binds to the NPR-B receptor, counteracting the FGFR3 signal and promoting endochondral bone growth. The drug is administered as a daily subcutaneous injection.

The FDA approved Voxzogo in November 2021 for children aged 5 and older with open growth plates. The drug generated over $700 million in 2025 revenue. The existing label covers the 5-and-up population, where growth velocity has already slowed. The sNDA seeks to extend treatment to children under 5, the age window where growth velocity is highest and where skeletal deformities become established.

The sNDA data

The sNDA is backed by Phase 2 data in infants and young children ages 0 to 5. The primary endpoint is annualized growth velocity. In the trial, children treated with vosoritide showed a statistically significant increase in annualized growth velocity compared to baseline, with the effect sustained over 12 months. The safety profile was consistent with the 5-and-up population, with injection site reactions and blood pressure decreases being the most common adverse events.

Vosoritide lowers blood pressure because CNP is a vasodilator. In infants, this requires careful dose monitoring. The Phase 2 data showed a manageable safety profile, but the FDA may ask for additional long-term safety data in this younger population. This is the primary regulatory risk.

The commercial opportunity

Expanding the label to children under 5 increases the addressable patient population by 30-40%. Achondroplasia affects roughly 1 in 25,000 births, or about 160 new cases per year in the U.S. The under-5 population is smaller in absolute numbers but represents the highest-value patients because early intervention can prevent the skeletal complications that develop later.

If approved, Voxzogo’s peak sales could increase from $700 million to $1 billion or more. At BioMarin’s current valuation, that incremental $300 million in revenue is meaningful but not transformative. The stock already prices in a high probability of approval.

For context on rare disease PDUFA catalysts, see our rare disease catalyst roundup and our analysis of a comparable rare disease PDUFA.

The competitive threat

Voxzogo faces two emerging competitors. BridgeBio’s infigratinib, an oral FGFR1-3 inhibitor, is in Phase 3 for achondroplasia. An oral therapy would be more convenient than daily injections. Ascendis Pharma’s TransCon CNP, a long-acting CNP analog, is also in development and would require less frequent dosing.

If either competitor shows superior efficacy or convenience, Voxzogo’s franchise could face erosion. The under-5 label expansion helps BioMarin lock in patients earlier, before competitors arrive. This is a defensive move as much as an offensive one.

The verdict

This is a franchise expansion, not a binary bet. Voxzogo is already generating $700 million in revenue. The sNDA approval would increase that by 30-40%, but the stock at $59.99 is pricing in a high probability of success. The downside if the FDA issues a complete response letter (CRL) is limited because the existing franchise remains intact. For background on what a CRL means, see our CRL explainer.

The specific risk is that the FDA asks for an additional safety trial in infants. CNP’s blood pressure effects are well-characterized, but the agency has been cautious with pediatric populations. If the FDA requires a new trial, the timeline pushes out by 12-18 months, and Voxzogo loses the first-mover advantage in the under-5 segment.

At $11.7 billion, BioMarin is trading at roughly 16x 2025 revenue. That is a premium valuation for a rare disease company with a single dominant franchise. The pipeline beyond Voxzogo includes BMN-331 (gene therapy for hearing loss) and BMN-270 (hemophilia A gene therapy), but neither is near-term. The stock’s performance over the next 12 months depends more on the Voxzogo sNDA than on any other catalyst.

I would hold BMRN if you already own it. I would not buy it ahead of the PDUFA. The risk-reward is symmetric and the market has already priced in the most likely outcome.

Source: BioMarin Voxzogo prescribing information