Study to Evaluate the Safety, PK, PD, and Efficacy of PRX-102 in Japanese Patients With Fabry Disease

Inclusion criteria (all subjects)

• Must have been born in Japan and have their biological parents and all 4grandparents of Japanese descent

• A documented diagnosis of Fabry disease, as determined by the following:

• Males: Plasma and/or leukocyte alpha-galactosidase-A activity (by activity assay)that is ≤ 5% of mean normal laboratory levels or, if the enzymatic activity is abovethe 5% limit but still under the normal level, a confirmed disease-causing mutationof the GLA gene

• Females: Historical genetic test results consistent with Fabry mutations or, in thecase of novel mutations, a first-degree male relative with Fabry disease

• All subjects: At least one of the following characteristic features of Fabrydisease: neuropathic pain, cornea verticillata, and/or clustered angiokeratoma

• Estimated glomerular filtration rate (eGFR) at screening ≥40 mL/min/1.73 m2. Foradults, this will be calculated using the Chronic Kidney Disease EpidemiologyCollaboration (CKD-EPI) Creatinine equation (2009); and for adolescents, it will becalculated using the Creatinine Cystatin C-based Chronic Kidney Disease in Children (CKiD) equation.

• Clinical condition that in the opinion of the Investigator requires treatment withERT

Additional inclusion criteria for subjects in Cohort A

• Aged ≥18 to ≤60 years

• Treatment with agalsidase beta for at least the last 12 months prior to screening,with the dose stable (defined as having received at least 80% of the labelled dose)for at least the last 6 months

• Diagnosis of kidney impairment, defined as a linear slope of eGFR more negative orequal to -2 mL/min/1.73 m2/year. The historical eGFR slope will be calculated basedon at least 3 serum creatinine values obtained over the past 9 to 24 months prior toscreening, using the CKD-EPI Creatinine equation (2009). This criterion will beconfirmed at screening by calculating the screening eGFR slope using historical andscreening serum creatinine values. Both historical and screening eGFR slopes will beused for the diagnosis of kidney impairment.

Additional inclusion criterion for subjects in Cohort B

• Aged ≥18 to ≤60 years

Additional inclusion criteria for subjects in Cohort C

• Aged ≥13 to <18 years

• If they previously received or are currently receiving ERT treatment, the subjectsmust be negative for anti-drug antibodies for PRX-102

Exclusion Criteria:

• Administration of ERT for Fabry disease within 14 days before baseline, substratereduction therapy for Fabry disease within 3 days before baseline, or chaperonetherapy for Fabry disease within 3 days before baseline

• History of type I hypersensitivity reactions (anaphylactic or anaphylactoidlife-threatening reaction) to other ERT treatment for Fabry disease or to anycomponent of the study drug

• Cohort A only: eGFR value of >90 to ≤120 mL/min/1.73 m2 at screening and ahistorical eGFR value >120 mL/min/1.73 m2 in the past 9 to 24 months beforescreening, indicating absence of renal impairment

• Urine protein to creatinine ratio (UPCR) >0.5 g/g (0.5 mg/mg or 500 mg/g) if nottreated with an ACE inhibitor or ARB

• Initiation of treatment, or a change in dose to ongoing treatment, with anangiotensin-converting-enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in the 4 weeks prior to screening.

• Currently taking another investigational drug for any condition

• Carry only known non-pathogenic Fabry mutations

• History of renal dialysis or kidney transplantation

• History of acute kidney injury in the 12 months prior to screening, includingspecific kidney diseases (e.g., acute interstitial nephritis, acute glomerular andrenal vasculitis); non-specific conditions (e.g., ischemia, toxic injury); as wellas extrarenal pathology (e.g., prerenal azotaemia, and acute postrenal obstructivenephropathy

• History of (or current) malignancy requiring treatment; the one exception is a priorhistory of resected basal cell carcinoma

• Severe cardiomyopathy or significant unstable cardiac disease within 6 months priorto screening

• A positive test for Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2)within 3 months prior to screening, using a validated molecular assay or validatedantigen assay

• Females: Pregnant or lactating, or of childbearing potential with a fertile malepartner and unwilling to use a highly reliable method of contraception from theinformed consent signature until 30 days after the last study treatment

• Presence of any medical, emotional, behaevioral, or psychological condition that inthe judgment of the Investigator could interfere with the subject's compliance withthe requirements of the study

• Previous treatment with cellular therapy or gene therapy for any condition