This is a 12-month, parallel treatment, Phase 3, double-blind, randomized, placebo-controlled study to evaluate the effect of venglustat on neuropathic and abdominal pain symptoms of Fabry disease in participants ≥16 years of age with Fabry disease who are treatment-naïve or untreated for at least 6 months.

• Study visits will take place approximately every 3 months.
• The double-blind period will be followed by an open-label extension (OLE) during which participants who have completed the double-blind period will be treated with venglustat for an additional 12 months or until the Common Study End of Treatment Day (CSEOTD).

Double blind period: the total duration will be up to approximately of 14 months (1 month of screening 12 month of treatment period, and a possible follow-up period of 1 month if no participation in the open label extension period)

Open-label extension period: the total duration will be approximately of 46 months (12 month of OLE treatment, additional OLE treatment until a common study end of treatment date (CSEOTD, approximately 33 months), and 1 month of follow-up period)

Inclusion Criteria:

• Male and female adult patients 16 year of age or older, who have had a previously confirmed diagnosis of Fabry disease and a history of clinical symptoms of Fabry disease
• Patients who are treatment-naïve or without prior treatment with an approved or experimental therapy for Fabry disease within at least 6 months prior to screening.
• Average score of ≥3 (0=no symptom, 10=symptom as bad as you can imagine) on the participant-defined most-bothersome symptom (among neuropathic pain in upper extremities, neuropathic pain in lower extremities, or abdominal pain), as measured by the Fabry Disease Patient-Reported Outcome (FD-PRO) at screening.
• Contraception (with double contraception methods) for male and female participants; not pregnant or breastfeeding for female participants; no sperm donation for male participants.
• Weight ≥30 Kg
• A signed informed consent must be provided prior to any study-related procedures.

Exclusion Criteria:

• Any manifestations of Fabry disease that preclude placebo administration.
• History of transient ischemic attack, stroke, myocardial infarction, heart failure, evidence of left ventricular hypertrophy and/or cardiac fibrosis, major cardiovascular surgery, or kidney transplantation.
• History of clinically significant cardiac arrhythmia. Atrial fibrillation that is well controlled on a stable medical regimen for at least 12 months is not an exclusion if the CHA2DS2-VASc score is 0 for males or 1 for females.
• Patients with hepatitis C, HIV, or hepatitis B infection.
• Neuropathic pain in upper or lower extremities, or abdominal pain not related to Fabry disease.
• History of seizures currently requiring treatment.
• Uncontrolled hypertension over the past 12 months prior to screening, or systolic BP >=150 or diastolic BP >=100 at screening.
• Estimated glomerular filtration rate <60 mL/min/1.73m².
• Urine protein to creatinine ratio >= 1 g/g at screening.
• Presence of severe depression as measured by Beck's Depression Inventory (BDI)-II >28 and/or a history of an untreated, unstable major affective disorder within 1 year of the screening visit.
• Positive SARS-CoV-2 virus test within 2 weeks of enrollment, or COVID 19 requiring hospitalization within 6 months of enrollment.
• Moderate to severe hepatic impairment.
• History of drug and/or alcohol abuse.
• History of or active hepatobiliary disease.
• Liver enzymes (alanine aminotransferase (ALT)/aspartate aminotransferase (AST)) or total bilirubin >2 times the upper limit of normal (ULN).
• Initiation of chronic treatment for pain, or change in pain medication regimen, within 3 months prior to randomization.
• Strong or moderate inducers or inhibitors of cytochrome P450 3A within 14 days or 5 half-lives, whichever is longer, prior to randomization.

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

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Participants enrolled in the open-label extension will be treated with venglustat only.