Evaluate the Safety, Pharmacodynamics, Pharmacokinetics, and Exploratory Efficacy of GZ/SAR402671 in Treatment-naïve Adult Male Patients With Fabry Disease

The total duration of study per patient is 7 to 8 months for patients who will enter a
planned extension study and approximately 13 to 14 months for patients who will not enter a
planned extension study. A 2-year extension study is planned for eligible patients.

Inclusion criteria:

- The patient is ≥18 years of age and <50 years of age.

- The patient is male.

- The patient has provided a signed informed consent.

- The patient had a confirmed diagnosis of Fabry disease as documented by leukocyte α-
Galactosidase A (αGAL) activity of <4 nmol/hr/mg leukocyte (preferred assay; results
from a central laboratory) or plasma αGAL <1.5 nmol/hr/mL (results from a central
laboratory).

- The patient has a plasma globotriaosylsphingosine (lyso-GL3) greater than or equal to
65 ng/mL.

- The patient has never been treated with a Fabry disease-specific treatment.

- If the patient is on renin-angiotensin-aldosterone system (RAAS) blockers and
antidepressants, the dose should be stable (ie, prescribed dose and frequency) for at
least the immediate 3 months prior to screening.

Exclusion criteria:

- The patient has an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m^2
using (Chronic Kidney Disease Epidemiology Collaboration) CKD-EPI.

- The patient has a median urine protein/creatinine ratio (PCR) ≥0.5 g/g (median of 3
overnight urine collections. Collection of each of the 3 samples must occur between 4
and 7 days of each other, and all samples must be collected within a 15 day period).
All 3 samples must be collected regardless of the results and results available prior
to Day 1.

- The patient had undergone a kidney transplant.

- The patient has either active or a history of clinically significant organic disease
(with the exception of the symptoms related to Fabry disease), including clinically
significant cardiovascular, hepatic, pulmonary, hematologic, neurological or renal
disease, or other medical condition, serious inter-current illness, or extenuating
circumstances that, in the opinion of the Investigator, would preclude participation
in the trial.

- The patient has abnormal liver function (serum total bilirubin >the upper limit of
normal, or serum alanine aminotransferase [ALT] and aspartate aminotransferase [AST]
>2.0 times the upper limit of normal).

- The patient has, according to World Health Organization (WHO) Grading a cortical
cataract (COR) >one-quarter of the lens circumference (Grade COR-2) or a posterior
subcapsular cataract (PSC) >2 mm (Grade PSC-2). Patients with nuclear cataracts are
not excluded.

- The patient is currently receiving potentially cataractogenic medications.

- The patient has received strong or moderate inducers or inhibitors of Cytochrome P450
3A4 (CYP3A4) per Food and Drug Administration (FDA) classification within 14 days
prior to enrolment or within 5 times the elimination half-life or PD half-life of the
medication, whichever is longer.

- The patient is scheduled for in-patient hospitalization, including elective surgery,
during the study.

- The patient has a positive result on any of the following tests: hepatitis B surface
antigen (HBsAg), anti-hepatitis C virus (anti-HCV) antibodies, anti-human
immunodeficiency virus 1 and 2 antibodies (anti-HIV1 and anti-HIV2 Ab). Patients with
a positive hepatitis B surface antibody (HBsAb) test with a history of prior
hepatitis B immunization are eligible if other criteria are met (ie, negative tests
for: HBsAg, hepatitis B core antibody [HBcAb], and hepatitis C virus antibody
[HCVAb]).

- The patient has participated in a study involving an investigational drug within the
past 30 days of the start of the trial.

- The patient is unwilling to comply with the requirements of the protocol.

- The patient is a sexually active man who is not willing to use 2 forms of birth
control including a barrier method during the study until 6 weeks after the last
treatment with IMP.

- The patient has history or ongoing clinically significant cardiac arrhythmia, defined
as either atrial fibrillation, sustained or non-sustained ventricular tachycardia.

- The patient has any contraindication to magnetic resonance imaging (MRI).

- The patient has one of the following central nervous system exclusion criteria:

- Acute stroke, within 3 months of the screening visit.

- History of seizures.

The above information is not intended to contain all considerations relevant to a
patient's potential participation in a clinical trial.