for people ages 18 years and up (full criteria)
at Orange, California and other locations
study started
estimated completion



The primary objective of the study is to evaluate the safety of UX053 in adults with Glycogen Storage Disease Type III (GSD III).

Official Title

A Phase 1/2 First-in-human, 2-part Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of Single Ascending Doses (Part 1: Open-label) and Repeat Doses (Part 2: Randomized, Double-blind, Placebo-controlled) of UX053 in Patients With GSD III


This study is a phase 1/2 first-in-human (FIH), 2-part study to evaluate the safety, tolerability, and pharmacokinetic (PK) of a single ascending dose (SAD; part 1) and repeat doses (RD; part 2) of UX053 in patients with GSD III. Single SAD and RD of UX053 are tested in separate cohorts. The SAD cohorts will be open-label, while the RD dose cohorts will be randomized, double-blind, and placebo-controlled.


Glycogen Storage Disease Type III, Glycogen Storage Disease, Disease, Acetaminophen, Antipyretics, Cetirizine, Ibuprofen, Famotidine, Antipyretic, H2 Blocker, H1 Blocker


You can join if…

Open to people ages 18 years and up

  • Confirmed diagnosis of GSD III by gene sequencing or enzymatic testing
  • Alanine aminotransferase at or below 5 times normal during the three months prior to dosing
  • Willing and able to comply with standard dietary management of GSD III

You CAN'T join if...

  • History of liver transplant or currently awaiting liver transplant
  • History of cirrhosis
  • Active Hepatitis B or C
  • Severe kidney impairment
  • History of liver cancer or large liver tumors
  • History of any cancer within the past 3 years
  • Known history of HIV infection
  • Known severe allergy to polyethylene glycol (PEG), polysorbate, or mRNA vaccine
  • Heart failure that causes marked limitation in physical activity
  • Poorly controlled diabetes
  • Poorly controlled hypothyroidism
  • Treatment with immunosuppressive medications such as those used to treat chronic autoimmune conditions and solid organ transplants
  • Pregnant or nursing, or planning to become pregnant during the study

Note: Additional inclusion/exclusion criteria may apply, per protocol


  • University of California, Irvine accepting new patients
    Orange California 92868 United States
  • University of Texas, Health Science Center of Houston accepting new patients
    Houston Texas 77030 United States


accepting new patients
Start Date
Completion Date
Ultragenyx Pharmaceutical Inc
Ultragenyx Patient Advocacy/GSD III Disease Information
Phase 1/2 Glycogen Storage Disease Type III Research Study
Study Type
Expecting 30 study participants
Last Updated