Dose-Ranging Study of ST-920, an AAV2/6 Human Alpha Galactosidase A Gene Therapy in Subjects With Fabry Disease (STAAR)

Prior treatment

• Neutralizing antibodies to AAV6
• Recent or recurrent hypersensitivity response to enzyme replacement therapy (ERT) within within 6 months prior to consent
• Current or history of systemic (IV or oral) immunomodulatory agents, or biologics or steroid use in the past 6 months prior to consent (topical treatment and inhaled allowed).
• Contraindication to use of corticosteroids
• Participation in investigational interventional drug or medical device study throughout the duration of this study and within previous 3 months prior to consent
• Prior treatment with a gene therapy product
• History of acute kidney insufficiency in the 6 months prior to screening
• Angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) therapy initiated within 4 weeks prior to screening or changed ACE inhibitor or ARB dose in the 4 weeks prior to screening
• Angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) therapy initiated within 4 weeks prior to screening or changed ACE inhibitor or ARB dose in the 4 weeks prior to screening

Other illness

• New York Heart Association Class III or higher
• Active infection with hepatitis A, B or C, human immunodeficiency virus (HIV) or tuberculosis (TB)
• History of liver disease such as clinically significant steatosis, fibrosis, non-alcoholic steatohepatitis (NASH) and cirrhosis, biliary disease within 6 months of informed consent; except for Gilbert's syndrome
• History of malignancy except for non-melanoma skin cancer and localized prostate cancer treated with curative intent
• Recent history of alcohol or substance abuse
• Known hypersensitivity to components of ST-920 formulation
• Any other reason that, in the opinion of the Site Investigator or Medical Monitor, would render the subject unsuitable for participation in the study including but not limited to risk of COVID-19 infection
  • Additional exclusion criteria for:
  • Renal cohort:
• History of renal dialysis or transplantation
• Significant cardiac fibrosis defined by late gadolinium enhancement on CMR
• New York heart association (NYHA) Class IV

Lab values

• eGFR \< 40 ml/min/1.73m2
• Elevated circulating serum alpha fetoprotein (AFP)
• Urine protein to creatinine ratio (UPCR) \> 0.5 g/g who are not being treated with an ACE inhibitor or ARB
  • Cardiac cohort:

Other

• Any contraindications to CMR as per local hospital/institution guidelines

• ≥ 18 years of age
• Documented diagnosis of Fabry disease
• One or more of the following symptoms: i) cornea verticillata, ii) acroparesthesia, iii) anhidrosis, iv) angiokeratoma
• Subject must be fully vaccinated (as per the Centers for Disease Control and Prevention (CDC) definition in the US and as per local guidelines in other countries) for Coronavirus Disease (COVID-19) at least one month prior to dosing
  • Additional Inclusion Criteria:
  • Renal Cohort:
• Screening estimated glomerular filtration rate (eGFR) value between 40-90 mL/min/1.73 m²
• Linear negative eGFR slope (estimated from at least 3 serum creatinine values within 18 months, including the value obtained during screening visit) of ≥ 2 mL/min/1.73m²/year
  • Cardiac Cohort:
• Left ventricular hypertrophy (LVH) in 2D echocardiography or cardiac magnetic resonance imaging (CMR) defined as an end diastolic septum and posterior wall thickness ≥12 mm with no other explanation for LVH, OR presentation with cardiac changes indicative of disease progression such as decreased global longitudinal strain on 2D strain echocardiography or low native T1 mapping on CMR