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NCT Number: NCT07216066

First-in-Human Study of ALN-SNCA in Adult Participants With Early Parkinson's Disease (PD)

This study is researching an experimental drug called ALN-SNCA (called "study drug"). The study is focused on people with early Parkinson's disease, a disorder of the nervous system that affects movement. Parkinson's disease is caused by a gradual loss of nerve cells in the brain, especially those due to the harmful build-up of a protein called α-synuclein.

The aim of the study is to see if the study drug is safe and tolerated well enough to continue testing it in future studies and what side effects may happen from taking the study drug.

The study is looking at several other research questions, including:

* Whether the study drug can lower the level of α-synuclein protein in the Cerebrospinal Fluid (also referred to as "CSF", the fluid that surrounds the brain and spinal cord) * How much study drug is in the blood, urine, and CSF at different times * Compatible research to better understand the study drug (ALN-SNCA) and Parkinson's disease, including (but not limited to), whether the study drug can slow down the progression of Parkinson's disease symptoms

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Key information

Conditions

Parkinsons Disease Autonomic Nervous System Diseases Basal Ganglia Diseases Brain Diseases Central Nervous System Diseases Cognition Disorders Cognitive Dysfunction Dyskinesias Mental Disorders Mood Disorders Movement Disorders Muscle Hypertonia Muscle Rigidity Muscular Diseases Musculoskeletal Diseases Nervous System Diseases Neurocognitive Disorders Neurodegenerative Diseases Neurologic Manifestations Neuromuscular Manifestations Parasomnias Parkinson Disease Parkinsonian Disorders Pathological Conditions, Signs and Symptoms Primary Dysautonomias Signs and Symptoms Sleep Wake Disorders Synucleinopathies Tremor

Age range

50 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

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

Key Inclusion Criteria:

  • Diagnosis of Parkinson's disease according to the Movement Disorder Society (MDS) criteria, as assessed by the investigator, with bradykinesia plus at least one of the other cardinal signs of Parkinson's disease (resting tremor, rigidity), without any other known or suspected cause of Parkinsonism
  • A diagnosis of Parkinson's disease for 4 years or less at the screening visit
  • Participant must meet one of the following criteria:
  • Currently not receiving any standard-of-care (SoC) therapy for Parkinson's disease, has not been on oral dopaminergic therapy (ie, levodopa, dopamine agonists, or Monoamine Oxidase B [MAO-B] inhibitors) prior to dosing, and is not anticipated to require SoC therapy for Parkinson's disease within approximately 6 months following dosing, or
  • Has been on a stable regimen of oral dopaminergic therapy for at least 3 months prior to dosing and is not anticipated to require dose adjustments within approximately 6 months following dosing
  • BMI ≤35 kg/m^2 at time of screening visit

Key Exclusion Criteria:

  • Medical history indicating a Parkinsonian syndrome other than Parkinson's disease, as defined in the protocol
  • Clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric or neurological disease (excluding Parkinson's disease) that, as assessed by the investigator, may confound the results of the study or pose an additional risk to the participant during study participation
  • Medical history of brain or spinal disease/injury that would interfere with the Lumbar Puncture (LP) procedure or CSF circulation, as defined in the protocol
  • Any contraindications to undergo a brain Magnetic Resonance Imaging (MRI)
  • An established allergy or intolerance to lidocaine anesthetic, as defined in the protocol
  • History of intolerance to Intrathecal (IT) injection(s)
  • Current history of bleeding diatheses that would increase risk of bleeding upon LP
  • Has undergone gene therapy, cell therapy or surgical treatment, including deep brain stimulation, for Parkinson's disease

NOTE: Other Protocol-defined Inclusion/Exclusion Criteria Apply

Treatment and study plan

ALN-SNCA

Drug

Administered per the protocol

Placebo

Drug

Administered per the protocol

Primary outcomes

  1. Occurrence of Treatment-Emergent Adverse Events (TEAEs)

    Time frame: Through Week 80

  2. Severity of TEAEs

    Time frame: Through Week 80

Secondary outcomes

  1. Concentration of alpha (a)-synuclein protein in CSF

    Time frame: Through Week 48

  2. Change from baseline in concentration of a-synuclein protein in CSF

    Time frame: Through Week 48

  3. Concentration of ALN-SNCA in plasma

    Time frame: Through Week 48

  4. Concentration of major metabolites in plasma

    Time frame: Through Week 48

  5. Concentration of ALN-SNCA in CSF

    Time frame: Through Week 48

  6. Concentration of major metabolites in CSF

    Time frame: Through Week 48

  7. Fraction [fc] of ALN-SNCA excreted in urine

    Time frame: Over 24 hours

  8. Fc of major metabolites excreted in urine

    Time frame: Over 24 hours

Study contacts

Contact information is provided by the study sponsor or research team.

Clinical Trials Administrator

CONTACT

[email protected]

844-734-6643

Sponsors and collaborators

Lead sponsor

Regeneron Pharmaceuticals

Industry

Registry information

Official study title

First-in-Human Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Ascending Doses of Intrathecally Administered ALN-SNCA in Participants With Early Parkinson's Disease

Important dates

Study start
2025
Primary completion
2029
Study completion
2029
First posted
Oct 14, 2025
Registry last updated
Apr 14, 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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