Ultragenyx Stock Declines After Missing Primary Endpoints on its Phase III Orbit and Cosmic Studies

Rhea-AI Summary

Ultragenyx (Nasdaq: RARE) announced topline results from Phase III Orbit and Cosmic studies of setrusumab (UX143) for osteogenesis imperfecta showing both studies failed their primary endpoint of reducing annualized clinical fracture rate versus placebo (Orbit) and versus bisphosphonates (Cosmic).

The studies did show improved bone density but that secondary result did not correlate with lower fracture rates. Management cited a low placebo-group fracture rate as an explanation. Analyst coverage turned cautious with firms, including Barclays, noting limited approval prospects. Levi & Korsinsky has opened an investigation related to the announcement.

Positive

• Phase III showed improved bone density in tested patients
• Company completed two pivotal Phase III studies (Orbit and Cosmic) with topline readouts

Negative

• Both Phase III studies failed primary endpoint for reduction in annualized clinical fracture rate
• Improved bone density did not translate to reduced fracture rates
• Analysts reduced outlooks and slashed price targets, citing limited approval prospects
• Levi & Korsinsky opened an investigation, introducing potential litigation risk

Key Figures

Phase III studies: 2 Phase III studies (Orbit and Cosmic) Phase II reliance: Phase II Orbit data Firm track record: 20 years +2 more

5 metrics

Phase III studies 2 Phase III studies (Orbit and Cosmic) UX143 in osteogenesis imperfecta

Phase II reliance Phase II Orbit data Previously cited to support causal link bone density–fracture rate

Firm track record 20 years Levi & Korsinsky history securing recoveries for shareholders

Employee count Over 70 employees Levi & Korsinsky staffing for securities litigation practice

Top 50 ranking 7 consecutive years Firm ranked in ISS Securities Class Action Services’ Top 50 Report

Market Reality Check

Price: $23.40 Vol: Volume 2,323,511 is below...

low vol

$23.40 Last Close

Volume Volume 2,323,511 is below the 20-day average of 4,076,909 (relative volume 0.57x). low

Technical Price at $23.40, trading below the 200-day MA of $32.24 and 49.68% under the 52-week high.

Peers on Argus

RARE showed a 2.86% gain while peers like TLX, XENE, NAMS, SLNO, and SRRK rose b...

RARE showed a 2.86% gain while peers like TLX, XENE, NAMS, SLNO, and SRRK rose between 0.57% and 4.22%. No peers appeared in the momentum scanner and no same-day peer headlines were recorded, suggesting this legal-focused follow-up to the UX143 trial miss was more stock-specific than a coordinated sector move.

Previous Clinical trial Reports

4 past events · Latest: 2025-12-29 (Negative)

Same Type Pattern 4 events

Date	Event	Sentiment	Move	Catalyst
2025-12-29	Phase 3 trial results	Negative	-42.3%	UX143 Orbit and Cosmic Phase 3 failed primary endpoints but improved BMD.
2025-09-08	Positive Phase 3 data	Positive	-0.0%	DTX401 96-week data showed strong cornstarch reduction and quality-of-life gains.
2025-07-31	Trial enrollment update	Positive	+4.1%	Completed Phase 3 Aspire enrollment for GTX-102 in Angelman syndrome.
2025-07-09	Trial progression update	Positive	-25.1%	UX143 Orbit study cleared to final analysis with acceptable safety profile.

Pattern Detected

Clinical trial updates have produced large, often asymmetric moves, with both strong selloffs on negative data and notable swings even on positive or mixed results.

Recent Company History

Over the last six months, Ultragenyx’s key news flow has centered on clinical trial milestones. The Dec 29, 2025 UX143 Orbit/Cosmic Phase 3 miss led to a -42.32% move and expense reduction plans. Other clinical updates on DTX401 and GTX-102 highlighted meaningful efficacy signals, enrollment progress, and acceptable safety, but market reactions ranged from slightly negative to modestly positive. This investigation-focused article revisits the same UX143 outcome that previously triggered the sharp decline.

Historical Comparison

clinical trial

+17.9 %

Average Historical Move

Historical Analysis

In the past year, RARE had 4 clinical trial updates with an average move of ±17.89%. The current law-firm investigation revisits the same UX143 Phase 3 miss that previously drove a -42.32% reaction, fitting a pattern of outsized sensitivity to pivotal clinical outcomes.

Typical Pattern

Recent clinical news shows UX143 progressing from interim monitoring to a negative Phase 3 outcome, while DTX401 and GTX-102 advanced with encouraging long-term efficacy and enrollment milestones across multiple late-stage programs.

Market Pulse Summary

This announcement revisits Ultragenyx’s UX143 Phase 3 Orbit and Cosmic results, which failed primary...

Analysis

This announcement revisits Ultragenyx’s UX143 Phase 3 Orbit and Cosmic results, which failed primary fracture-rate endpoints despite improved bone density and previously triggered a -42.32% move on Dec 29, 2025. The law-firm investigation highlights continued legal scrutiny rather than new clinical data. In context, RARE has shown large swings around clinical trial news, so future attention may focus on upcoming gene therapy milestones and any further analyses of UX143 outcomes.

Key Terms

phase iii, phase ii, osteogenesis imperfecta, placebo, +3 more

7 terms

phase iii medical

"topline results from its Phase III Orbit and Cosmic Studies, focusing"

A Phase III trial is the late-stage clinical study that tests whether a medical treatment works and is safe in a large group of patients, often comparing it to standard care. Think of it as a final dress rehearsal or full-scale road test before regulators decide on approval; positive or negative results strongly influence a drug maker’s chance to sell the treatment, future revenue, and investment risk.

phase ii medical

"relied on the results Phase II of the Orbit study to claim"

Phase II is the mid-stage clinical trial where a potential drug or medical treatment is tested in a larger group of patients to see if it works and to help determine the best dose and common side effects. For investors, Phase II results matter because they give the first meaningful evidence about effectiveness and safety—like a road test that shows whether a product has real promise before a much bigger, costly final trial and potential regulatory approval.

osteogenesis imperfecta medical

"setrusumab (UX143) on Osteogenesis Imperfecta. Investors with concerns"

A genetic disorder that makes bones unusually fragile because the body produces faulty or too little of the protein that gives bone its strength; think of bones like a building made from weak bricks rather than strong ones. Investors track it because treatments, diagnostics, or therapies for the condition can create markets, affect clinical trial outcomes, regulatory approvals, and potential revenue for biotech and pharmaceutical companies developing interventions.

placebo medical

"endpoint of a reduction in annualized clinical fracture rate against placebo in the Orbit"

A placebo is an inactive pill, injection or procedure that looks and feels like the real treatment but contains no therapeutic ingredient, often called a sugar pill. Investors care because comparing a drug to a placebo reveals whether observed benefits come from the medicine itself or from expectation; clear superiority over placebo reduces regulatory and commercial risk, much like a blind taste test proves a new recipe really tastes better.

bisphosphonates medical

"against biophosphonates, the standard care, in the Cosmic study."

Bisphosphonates are a class of medications that slow the breakdown of bone and help prevent fractures, commonly used to treat conditions that weaken bone strength. For investors, they matter because approval, patent status, pricing, safety warnings or new clinical results can quickly change sales and liability profiles for drugmakers—think of them as a protective coating for a company’s revenue in the large market for bone-health treatments.

annualized clinical fracture rate medical

"primary endpoint of a reduction in annualized clinical fracture rate against placebo"

The annualized clinical fracture rate is the average number of medically confirmed bone breaks expected per person over one year in a clinical study, calculated by accounting for both the number of fractures and how long participants were observed. Investors use it to gauge a drug or device’s real-world effectiveness at preventing fractures—like measuring accidents per driver per year—because lower rates suggest stronger clinical benefit and a clearer path to market adoption and revenue.

securities litigation financial

"expertise representing investors in complex securities litigation and a team"

Securities litigation is a legal dispute brought by investors, regulators, or other parties alleging false statements, misleading information, insider trading, or other wrongdoing tied to the buying, selling, or holding of stocks, bonds or other financial instruments. It matters to investors because lawsuits can produce fines, payouts, damaged reputations and sharp stock moves—like a costly product recall or lawsuit that forces a company to pay and rebuild trust, potentially reducing shareholder value and altering future prospects.

AI-generated analysis. Not financial advice.

NEW YORK, Jan. 23, 2026 /PRNewswire/ -- Levi & Korsinsky, LLP is investigating Ultragenyx Pharmaceutical Inc. (Nasdaq: RARE) following the Company's announcement of topline results from its Phase III Orbit and Cosmic Studies, focusing on the effectiveness of setrusumab (UX143) on Osteogenesis Imperfecta. Investors with concerns about Ultragenyx's business operations may click here for more information.

Ultragenyx reported the study results on December 29, 2025. Both studies failed to achieve their primary endpoint of a reduction in annualized clinical fracture rate against placebo in the Orbit study and against biophosphonates, the standard care, in the Cosmic study.

The Phase III studies also failed to correlate the secondary result to a reduction in fracture rate, despite successfully showing an improvement in the tested patients' bone density. Ultragenyx had previously relied on the results Phase II of the Orbit study to claim a causal link between improved bone density and a reduction in annualized fracture rate.

In announcing the results, the company pointed to a "low fracture rate in the placebo group" as a justification for Orbit's failed results. Management had previously highlighted there were no "uncontrolled factors" in the study and they had crafted the study in such a way to "actually increase their fractures, which would give [them] more opportunities to see the difference between [the test groups]."

Analyst coverage following the results turned cautious as analysts quickly began slashing their price targets. Barclays noted it now sees "limited opportunity for drug approval despite some trend of clinical benefit."

Those with questions about Ultragenyx's operations may contact the firm for a confidential discussion.

Levi & Korsinsky maintains a national securities practice with offices in New York, California, Connecticut, and D.C. Over the past 20 years, the team at Levi & Korsinsky has secured hundreds of millions of dollars for aggrieved shareholders and built a track record of winning high-stakes cases. Our firm has extensive expertise representing investors in complex securities litigation and a team of over 70 employees to serve our clients. For seven years in a row, Levi & Korsinsky has ranked in ISS Securities Class Action Services' Top 50 Report as one of the top securities litigation firms in the United States.

CONTACT:
Joseph E. Levi, Esq.
Levi & Korsinsky, LLP
33 Whitehall Street, 27th Floor
New York, NY 10004
Tel: (212) 363-7500
Fax: (212) 363-7171
Email: jlevi@levikorsinsky.com
www.zlk.com

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SOURCE Levi & Korsinsky, LLP

FAQ

What did Ultragenyx (RARE) announce about the Phase III Orbit and Cosmic studies on Jan 23, 2026?

Both Phase III studies of setrusumab (UX143) failed their primary endpoint of reducing annualized clinical fracture rate; results were announced as topline readouts.

Did the setrusumab Phase III studies show any positive clinical signals for RARE?

Yes; both studies showed an improvement in bone density, but that improvement did not correlate with fewer fractures.

How did analysts react to Ultragenyx's Phase III results for RARE?

Analyst coverage turned cautious and firms, including Barclays, cut price targets and noted limited approval opportunity.

What legal or shareholder actions followed Ultragenyx's RARE study announcement?

Levi & Korsinsky announced it is investigating Ultragenyx following the topline Phase III results.

What reason did management give for Orbit study failing to show fracture reduction for RARE?

Management pointed to a reported low fracture rate in the placebo group as a contributing factor.