Ultragenyx secures FDA IND clearance for UX016, a sialic acid prodrug, advancing into a Phase 1/2 trial for GNE myopathy with no approved treatments.
Written By: Chikkula Pavan Kumar, PharmD
Reviewed By: Pharmacally Editorial Team
Ultragenyx Pharmaceutical has received clearance from the U.S. Food and Drug Administration for its Investigational New Drug (IND) application for UX016, enabling the program to advance into clinical development for patients with GNE myopathy (GNEM). The investigational therapy is a small-molecule prodrug of sialic acid designed as a substrate replacement approach for this rare, progressive neuromuscular disorder.
UX016 is engineered to address a core disease mechanism in GNEM, which is caused by mutations in the GNE gene that impair the body’s ability to produce sufficient sialic acid. This deficiency leads to progressive muscle degeneration, loss of mobility, and eventual dependence on caregivers. Currently, there are no approved disease-modifying treatments available for GNEM.
Emil Kakkis, Chief Executive Officer and President of Ultragenyx Pharmaceutical Inc., said advancing UX016 into clinical trials marks a key milestone for GNE myopathy, highlighting its potential to improve sialic acid uptake in muscle and address significant unmet needs, supported by an innovative external funding model and collaboration with physicians and the patient community.
The upcoming first-in-human Phase 1/2 study is expected to begin in the second half of 2026 in the United States. The trial will enroll approximately 24 adults aged 18 to 55 years with GNEM. The study will assess safety, pharmacokinetics, and muscle delivery of UX016 at two dose levels compared with placebo over an initial 12-week period. Longer-term evaluation through Week 48 will include measures of upper and lower muscle strength, functional outcomes, and patient-reported endpoints relevant to disease burden.
The UX016 program is being supported through an external funding model led by the Neuromuscular Disease Foundation, which is backing the program through clinical proof-of-concept. This collaborative approach reflects growing involvement of patient groups in accelerating early-stage rare disease research.
GNE myopathy, also known as hereditary inclusion body myopathy, affects an estimated 10,000 individuals in commercially accessible regions. The condition typically presents in adulthood and progresses to severe muscle weakness, with many patients eventually losing ambulation. By targeting the underlying sialic acid deficiency, UX016 aims to offer a mechanistically driven therapeutic option for a population with significant unmet medical need. Ultragenyx plans to work closely with clinicians and the patient community as the program transitions into clinical evaluation.
Reference
Ultragenyx Announces FDA Clearance of Investigational New Drug (IND) Application for UX016, a Sialic Acid Prodrug for the Treatment of GNE Myopathy, 30 March 2026, Ultragenyx Announces FDA Clearance of Investigational New Drug (IND) Application for UX016, a Sialic Acid Prodrug for the Treatment of GNE Myopathy—Ultragenyx Pharmaceutical Inc.
About the Writer
Chikkula Pavan Kumar, Pharm.D. is a Doctor of Pharmacy with a keen interest in clinical pharmacy, pharmacovigilance, and evidence-based practice. In his words, he is passionate about patient safety and translating complex medical information into clear, research-driven communication.