Study to Evaluate the Safety and EffIcacy of PRX-102 on Gastrointestinal Symptoms in Naïve Fabry Disease

A Randomized, Double Blind, Placebo-Controlled Study to Evaluate the Safety and Efficacy of PRX-102 on Gastrointestinal Symptoms in Naïve Fabry Disease Patients

The study will be a randomized, double blind, placebo-controlled study of the safety and efficacy of PRX-102 in ERT naïve male patients randomized 1:1. Patient age will be 14 to 45 years. Patients must have diarrhea defined as ≥ 3 stools a day with an average consistency of ≥ 5.5 on the Bristol Stool Form Scale (BSFS) by patient electronic diary and moderate to severe gastrointestinal symptoms as defined by the Irritable Bowel Symptom Severity Score (IBSSS) Part 1 average > 175 derived from at least two IBSSS assessments during screening period. Patients will receive intravenous infusions of PRX-102 1 mg/kg or placebo every two weeks for 6 months.

Inclusion Criteria:

• Males, age 14-45 years, naïve to enzyme replacement therapy (ERT) or off ERT or off chaperone treatment for at least 6 months and negative for anti-PRX-102 antibodies

• A documented diagnosis of Fabry disease: Plasma and/or leucocyte alpha galactosidase activity (by activity assay) less than lower limit of normal (LLN)

• eGFR by CKD-EPI > 30 ml/min/1.73 m2

• Moderate to severe gastrointestinal symptoms as defined by:

  • Average score of > 175 from at least two Irritable Bowel Symptom Severity Score (IBSSS) Part 1 assessments before randomization.
  • Average stool consistency of ≥ 5.5 on the Bristol Stool Form Scale (BSFS) by patient diary during 2 weeks prior to randomization out of the 4 week of screening period and
  • ≥ 3 stools a day with a consistency of ≥ 5 on the BSFS during the week before randomization.

• Completed electronic BSFS diary on at least 6 of the 7 days during the week prior to randomization AND at least 11 of the 14 days during the 2 weeks prior to randomization.

Exclusion Criteria:

• Patients will be evaluated to rule out other gastrointestinal comorbidity than Fabry disease as responsible for the gastrointestinal symptoms by:

  i. Medical History for non Fabry gastrointestinal comorbidity ii. Occult blood in stool iii. Stool culture for bacteria and parasites iv. Calprotectin in stool v. Sigmoidoscopy

• Use of any kind of laxatives

• Initiation of anti-diarrheal medications during the screening period

• History of renal dialysis or transplantation

• Use of, or change in dose of, angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) for less than 4 weeks prior to screening

• Cardiovascular event (myocardial infarction, unstable angina) in the 6 month period before randomization

• Congestive heart failure NYHA Class IV

• Cerebrovascular event (stroke, transient ischemic attack) in the 6 month period before randomization

• Known history of hypersensitivity to Gadolinium contrast agent

• Known allergies to ERT

• Presence of any medical, emotional, behavioral or psychological condition that, in the judgment of the Investigator and/or Medical Director, would interfere with the patient's compliance with the requirements of the study