A Phase 3 Study of UX003 Recombinant Human Betaglucuronidase (rhGUS) Enzyme Replacement Therapy in Patients With Mucopolysaccharidosis Type 7 (MPS 7)

A Randomized, Placebo-Controlled, Blind-Start, Single-Crossover Phase 3 Study to Assess the Efficacy and Safety of UX003 rhGUS Enzyme Replacement Therapy in Patients With MPS 7

The Phase 3 study will use a novel randomized, intra-subject placebo-controlled, single crossover design, referred to as Blind Start, to evaluate the safety and efficacy of UX003. The Blind Start is a novel design whereby participants will be randomized to 1 of 4 groups, each representing a different treatment sequence, and will cross over to UX003 at different pre-defined time points in a blinded manner. All groups will receive a minimum of 24 weeks treatment with 4 mg/kg UX003 every other week (QOW).

Inclusion Criteria:

• Confirmed diagnosis of MPS 7 based on leukocyte or fibroblast glucuronidase enzyme assay or genetic testing.
• Elevated urinary glycosaminoglycan (uGAG) excretion at a minimum of 3-fold over the mean normal for age (at Screening).
• Apparent clinical signs of lysosomal storage disease as judged by the Investigator, including at least one of the following: enlarged liver and spleen, joint limitations, airway obstruction or pulmonary problems, limitation of mobility while still ambulatory.
• Aged 5 - 35 years, inclusive.
• Willing and able to provide written informed consent, or in the case of subjects under the age of 18 (or 16 years, depending on the region), provide written assent (if required) and written informed consent by a legally authorized representative after the nature of the study has been explained, and prior to any research-related procedures.
• Sexually active subjects must be willing to use acceptable highly effective methods of contraception while participating in the study and for 30 days following the last dose.
• Females of childbearing potential must have a negative pregnancy test at Screening and be willing to have additional pregnancy tests during the study. Females considered not of childbearing potential include those who have not experienced menarche, or have had tubal ligation at least one year prior to Screening, or who have had total hysterectomy.
• Naïve to treatment with UX003.

Exclusion Criteria:

• Undergone a successful bone marrow or stem cell transplant or has any degree of detectable chimaerism with donor cells.
• Major surgery within 3 months prior to study entry or planned major surgery during the study that may not allow safe participation in the study.
• Presence or history of any hypersensitivity to rhGUS or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects.
• Pregnant or breastfeeding at Screening or planning to become pregnant (self or partner) at any time during the study.
• Use of any investigational product (drug or device or combination) within 30 days prior to Screening, or requirement for any investigational agent prior to completion of all scheduled study assessments.
• Presence of a condition of such severity and acuity that, in the opinion of the Investigator, warrants immediate surgical intervention or other treatment or may not allow safe participation in the study.
• Concurrent disease or condition, or laboratory abnormality that, in the view of the Investigator, places the subject at high risk of poor treatment compliance or of not completing the study, or would interfere with study participation or introduce additional safety concerns.