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NCT Number: NCT07574034

A Single Patient Study of Sapropterin for Multisystem Smooth Muscle Dysfunction Syndrome

There is currently no approved treatment for multisystem smooth muscle dysfunction syndrome (MSMDS). This single-patient study is the first to be conducted in a child with MSMDS in Canada and was designed to provide the child with access to sapropterin treatment. The molecule we will be using, sapropterin (Kuvan), is already approved and available for other indications. This disease is caused by a genetic variant in the ACTA2 gene. This variant prevents the small units of actin fibers, which are the molecular motors of the smooth muscle cell, from assembling correctly. The goal is to gather data so that the drug can be approved for this indication and thus treat the patient.

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Key information

Conditions

Multisystemic Smooth Muscle Dysfunction Syndrome

Age range

1 month–18 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

CHU Sainte-Justine

Montreal, Quebec, H3T 1C5, Canada

About this study

We plan to repurpose sapropteride, a synthetic form of tetrahydrobiopterin (BH4), an essential cofactor of phenylalanine hydroxylase (PAH). Sapropteride is already approved in Canada for the treatment of phenylketonuria (PKU) and has shown promise as an agent against multisystem smooth muscle dysfunction syndrome (MSMS) in an animal model. No clinical trials are currently underway with sapropteride for MSMS.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients with the following molecularly confirmed genotype: ACTA2 c.536G>A, p.Arg179His
  • Aged 1 month to 18 years

Exclusion criteria

  • Previous exposure to Kuvan®, Biopten®, or any preparation of tetrahydrobiopterin for greater
  • Known hypersensitivity to Kuvan® or its excipients
  • Known hypersensitivity to other approved or non-approved formulations of tetrahydrobiopterin
  • Current use of medications that are known to affect nitric oxide synthesis, metabolism or action
  • Current use of experimental/other investigational or unregistered drugs that may affect the study outcomes
  • Inability to comply with study procedures
  • Concurrent disease or condition that would interfere with study participation or increase the risk for adverse events, including stroke, renal or hepatic failure
  • Other significant disease that in the Investigator's opinion would exclude the subject from the trial
  • Any condition that, in the view of the Principal Investigator renders the subject at high risk for failure to comply with treatment or to complete the study

Treatment and study plan

Kuvan (Sapropterine)

Drug

Sapropterine is already approved in Canada for the treatment of phenylketonuria (PKU) and has shown promise as an agent against multisystem smooth muscle dysfunction syndrome (MSMS) in an animal model. No clinical trials are currently underway with sapropteride for MSMS.

Primary outcomes

  1. Crossing of percentile of growth

    Time frame: 2 years

  2. Increase of mean diastolic blood pressure by more than 8 mmHg

    Time frame: 2 years

  3. Absence of cerebral vascular complications

    Time frame: 2 years

  4. Absence of progression of cerebral vascular disease

    Time frame: 2 years

Sponsors and collaborators

Lead sponsor

Gregor Andelfinger

Other

Registry information

Official study title

A Single Patient Study (SPS) of Sapropterin for Multisystem Smooth Muscle Dysfunction Syndrome (MSMDS).

Important dates

Study start
2026
Primary completion
2028
Study completion
2030
First posted
May 7, 2026
Registry last updated
May 7, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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