How the FDA Response on UX111 Is Shaping Ultragenyx Pharmaceutical's (RARE) Investment Narrative

• In late July 2025, Ultragenyx Pharmaceutical announced that its Phase 3 Aspire study for GTX-102 in Angelman syndrome fully enrolled 129 participants, while also receiving a Complete Response Letter from the FDA for its gene therapy UX111 targeting Sanfilippo syndrome type A, citing chemistry, manufacturing, and controls issues that require resubmission.
• While the FDA acknowledged positive efficacy data for UX111, the focus now shifts to addressing manufacturing concerns, even as pipeline progress continues with strong community support in other rare disease programs.
• We'll now explore how the FDA's Complete Response Letter for UX111 may affect Ultragenyx's investment narrative and future approval timelines.

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Ultragenyx Pharmaceutical Investment Narrative Recap

To believe in Ultragenyx Pharmaceutical as a shareholder, you need confidence in its ability to bring rare disease therapies to market, especially gene therapies like UX111. The recent FDA Complete Response Letter for UX111 introduces added uncertainty to the approval timeline, but it does not materially shift the main short-term catalyst, the pending Phase 3 Aspire readout for GTX-102, nor does it fundamentally change the key risk around execution in late-stage programs.

Among recent announcements, the full enrollment of the Phase 3 Aspire study of GTX-102 for Angelman syndrome is most relevant. This milestone keeps Ultragenyx on track for topline results in 2026, reinforcing a pipeline-driven catalyst while the company works through regulatory feedback for UX111, highlighting both momentum and ongoing risk tied to late-stage clinical and regulatory execution.

Yet even as Aspire advances, investors should be aware that continued financial losses and high R&D expenses...

Read the full narrative on Ultragenyx Pharmaceutical (it's free!)

Ultragenyx Pharmaceutical's outlook projects $1.3 billion in revenue and $140.6 million in earnings by 2028. This requires a 31.2% annual revenue growth rate and an earnings increase of $690.2 million from current earnings of -$549.6 million.

Uncover how Ultragenyx Pharmaceutical's forecasts yield a $87.21 fair value, a 207% upside to its current price.

Exploring Other Perspectives

Two Simply Wall St Community members estimate Ultragenyx’s fair value between US$87 and US$471 per share. This wide divergence of opinion comes as regulatory setbacks and persistent losses could influence cash needs and future growth, highlighting the importance of considering multiple viewpoints.

Explore 2 other fair value estimates on Ultragenyx Pharmaceutical - why the stock might be worth just $87.21!

Build Your Own Ultragenyx Pharmaceutical Narrative

Disagree with existing narratives? Create your own in under 3 minutes - extraordinary investment returns rarely come from following the herd.

• A great starting point for your Ultragenyx Pharmaceutical research is our analysis highlighting 2 key rewards and 1 important warning sign that could impact your investment decision.
• Our free Ultragenyx Pharmaceutical research report provides a comprehensive fundamental analysis summarized in a single visual - the Snowflake - making it easy to evaluate Ultragenyx Pharmaceutical's overall financial health at a glance.

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.