An Extension Study Assessing the Safety and Efficacy of AVTX-803 in Subjects With Leukocyte Adhesion Deficiency Type II

• AVTX-803 (Drug): L-fucose crystalline powder

Primary outcomes

• Incidence of treatment emergent adverse events reported during the study attributable to AVTX-803. [Through study completion, an average of 1 year.]

Secondary outcomes

• Sialyl-Lewis X antigen expression on leukocytes [At 6 months]
• Change from Baseline in the composite Nijmegen Pediatric Congenital Disorders of Glycosylation (CDG) Rating Scale (NPCRS) [Through study completion, an average of 1 year.]: The NPCRS comprises 3 sections, with each section containing specific items relevant to the assessment of subjects with CDG. Section I (Current Function); Section II (System Specific Involvement); and Section III (Current Clinical Assessment). The sum of the scores is used to scale patients into 3 domains: mild (0-14), moderate (15-25), and severe (>26) category.
• Change from Baseline in the individual parameters of the Nijmegen Pediatric Congenital Disorders of Glycosylation (CDG) Rating Scale (NPCRS) [Through study completion, an average of 1 year.]: The NPCRS comprises 3 sections, with each section containing specific items relevant to the assessment of subjects with CDG. Section I (Current Function); Section II (System Specific Involvement); and Section III (Current Clinical Assessment). The sum of the scores is used to scale patients into 3 domains: mild (0-14), moderate (15-25), and severe (>26) category.
• Goal Attainment Score (GAS) [Through study completion, an average of 1 year.]: The parent (or subject) formulates 3 individual goals for improving quality of life. Typically, these goals affect mobility, independence, and disease-related health aspects. These goals will be re-evaluated and scored by the parent or subject at each study visit within a scale of -2 to +2.
• Clinician Global Impression of Severity (CGI-S) [Through study completion, an average of 1 year.]: The CGI-S scale is a 7-point scale that assesses the severity of the subject's severity of disease/illness. 1=Normal, not ill at all; 2=borderline ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6= severely ill; 7=among the most extreme ill."

Sex: All, ages: 6 Months to 75 Years

Inclusion Criteria:

* Subject must have completed protocol AVTX-803-LAD-301
* Subject has biochemically and genetically proven LAD II (SLC35C1-CDG)

Exclusion Criteria:

* Subject has severe anemia defined as hemoglobin <8.0 g/dL (<4.9 mmol/L)
* Subject has impaired renal function as defined by an eGFR <90 mL/min
* Subject has known or suspected intolerance or hypersensitivity to fucose or any ingredients of the investigational product
* In the investigator's opinion, subject has a history of failure to respond to fucose at adequate dosing

• David Deyle, Principal investigator, Mayo Clinic