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RARE Reports New Upbeat Data From Sanfilippo Syndrome Drug Study

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Ultragenyx Pharmaceutical (RARE - Free Report) reported new findings from an ongoing, pivotal study of its investigational candidate, UX111 (ABO-102) AAV gene therapy, for Sanfilippo syndrome type A (MPS IIIA).

Per the data readout from the phase I/II/III Transpher A study, treatment with the candidate resulted in a statistically significant improvement in Bayley-III raw scores for cognition, receptive communication and expressive communication in MPS IIIA patients. Compared to natural history data from untreated patients, these improvements were linked to a notable and sustained reduction in cerebrospinal fluid (CSF) heparan sulfate (HS) levels. The data will be presented at an upcoming medical conference.

Ultragenyx stated that treatment with UX111 (3x10¹³ vg/kg) led to a rapid decline in CSF-HS levels within the first month, regardless of patient age or disease stage. As of August 2024, the median CSF-HS reduction was 65% across all treated patients and 66% in the modified intention-to-treat (mITT) group. The average follow-up duration was 34 months for all patients and 36 months for the mITT group, with the longest follow-up reaching 77 months.

In the past three months, shares of RARE have lost 10% compared with the industry’s 8.7% decline.

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Additionally, a pre-specified analysis found that all 10 patients treated with UX111 but excluded from the mITT group due to older age or advanced disease retained meaningful functional abilities at their last assessment. Aged 5.6 to 14.8 years, all maintained communication skills (3 verbal, 7 non-verbal), nine retained ambulation (8 independently, 1 with support), and nine preserved the ability to eat or self-feed. These findings are clinically significant, as such functions typically deteriorate and are lost in late childhood and early adolescence.

Ultragenyx also reported that all doses of UX111 were generally safe and overall well-tolerated. Treatment-related adverse events were mostly mild to moderate in severity and all resolved.

RARE’s Regulatory Filing for MPS IIIA Gene Therapy

In late 2024, Ultragenyx submitted a biologics license application (BLA) to the FDA for UX111 as a treatment for patients with MPS IIIA under the accelerated approval pathway. Ultragenyx’s BLA submission for UX111 is backed by data, including findings from the ongoing, pivotal phase I/II/III Transpher A study. Per the company, the latest efficacy data have also been included in the BLA submission package.

A final decision from the FDA and a potential U.S. launch are expected in the second half of 2025. Subject to approval, UX111 will become the first FDA-approved therapy for MPS IIIA in the United States. MPS IIIA is a rare fatal lysosomal storage disease that primarily affects the brain. Per Ultragenyx, approximately 3,000 to 5,000 patients in commercially accessible geographies are affected by this disease, with a median life expectancy of 15 years. UX111 was added to RARE’s pipeline following an exclusive license agreement with Abeona Therapeutics in 2022.

The investigational gene therapy enjoys the Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug designations in the United States. In the EU, it has been granted the PRIME and Orphan Medicinal Product designations.

Other Key Clinical Programs in RARE’s Pipeline

Ultragenyx has several other interesting gene therapy candidates in its pipeline. RARE and its partner, Mereo BioPharma, are jointly developing UX143 (setrusumab) monoclonal antibody forpediatric and young adult patients with osteogenesis imperfecta (OI) in two late-stage studies, Orbit and Cosmic. In October 2024, the FDA granted the Breakthrough Therapy designation to UX143 for the OI indication.

The company is also evaluating UX701, an investigational AAV9 gene therapy, in a phase I/II/III Cyprus2+ study to treat Wilson disease. In 2024, Ultragenyx announced that the phase III GlucoGene study (NCT05139316), evaluating its investigational AAV8 gene therapy, DTX401, to treat glycogen storage disease type Ia patients aged eight years and older achieved its primary endpoint with statistical significance. The GlucoGene study also met its key secondary endpoints. The next step for the company involves discussing these results with regulatory authorities to support a marketing application in mid-2025.

In December 2024, Ultragenyx announced dosing the first patient in the pivotal phase III Aspire study evaluating the efficacy and safety of GTX-102, its investigational antisense oligonucleotide, for Angelman syndrome (AS). The company is also on track to initiate an open-label clinical study, named Aurora, to evaluate the safety and efficacy of GTX-102 for treating other AS genotypes in other patient age groups in 2025. This additional study aims to enable treatment for a broader range of AS patients.

RARE’s Zacks Rank & Stocks to Consider

Ultragenyx currently carries a Zacks Rank #3 (Hold).

Some better-ranked stocks from the sector are Castle Biosciences (CSTL - Free Report) , BioMarin Pharmaceutical (BMRN - Free Report) and Alnylam Pharmaceuticals (ALNY - Free Report) . While CSTL and BMRN currently sporta Zacks Rank #1 (Strong Buy) each, ALNY carries a Zacks Rank #2 (Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

In the past 30 days, Castle Biosciences’ earnings estimates for 2024 have increased from 34 cents to 45 cents per share. During the same timeframe, the loss per share for 2025 has improved from $1.84 to $1.70. In the past three months, shares of Castle Biosciences have plunged 15.6%.

CSTL’s earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 172.72%.

In the past 30 days, estimates for BioMarin Pharmaceutical’s 2024 earnings per share have Improved from $3.28 to $3.29. Estimates for 2025 earnings per share have decreased from $4.05 to $4.01 during the same timeframe. In the past three months, BioMarin Pharmaceutical shares have lost 4.2%.

BMRN’s earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 28.7%.

In the past 30 days, estimates for Alnylam Pharmaceuticals’ 2024 loss per share have remained constant at 39 cents. The estimate for 2025 earnings per share is currently pegged at 41 cents. In the past three months, shares of Alnylam Pharmaceuticals have gained 2.3%.

ALNY’s earnings beat estimates in three of the trailing four quarters and matched once, delivering an average surprise of 65.67%.

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