A Phase 1 interventional study of ALN-SNCA and Placebo in Parkinsons Disease, sponsored by Regeneron Pharmaceuticals. Recruiting at 3 sites in 2 countries. Open to participants aged 50 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-09-21.
Sponsored by Regeneron Pharmaceuticals · Phase 1, Interventional, and Treatment
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:
4,573 studies on the registry are indexed under Parkinson Disease; 1,086 are open to participants now.
This study's planned enrollment of 46 is above the median of 40 across 3,353 interventional studies indexed under Parkinson Disease.
Browse Parkinson Disease studies →Regeneron Pharmaceuticals is the lead sponsor of 411 studies on the registry; 90 are open to participants now.
Of its 125 completed or terminated interventional studies of FDA-regulated products, 79 (63%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Participant must meet one of the following criteria:
Key Exclusion Criteria:
NOTE: Other Protocol-defined Inclusion/Exclusion Criteria Apply
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: ALN-SNCA
Drug: Placebo
Administered per the protocol
Administered per the protocol
Occurrence of Treatment-Emergent Adverse Events (TEAEs)
Time frame: Through Week 80
Severity of TEAEs
Time frame: Through Week 80
Concentration of alpha (a)-synuclein protein in CSF
Time frame: Through Week 48
Change from baseline in concentration of a-synuclein protein in CSF
Time frame: Through Week 48
Concentration of ALN-SNCA in plasma
Time frame: Through Week 48
Concentration of major metabolites in plasma
Time frame: Through Week 48
Concentration of ALN-SNCA in CSF
Time frame: Through Week 48
Concentration of major metabolites in CSF
Time frame: Through Week 48
Fraction [fc] of ALN-SNCA excreted in urine
Time frame: Over 24 hours
Fc of major metabolites excreted in urine
Time frame: Over 24 hours
Plan to share: Yes — All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report, Analytic code
Time frame: When Regeneron has: received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry) the legal authority to share the data, and ensured the ability to protect participant privacy
Access criteria: Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf
Data sharing details ↗ · vivli.org
No publications or documents are linked to this record.
Started Dec 2025 (actual). Primary completion is estimated for Jun 2029, 42 months after the start.
Of 127 industry-sponsored phase 1 interventional studies under Parkinson Disease, half reached primary completion within 8 months of starting (the median), counting those still running; a quarter within 3 and three quarters within 24. This study's planned 42 months is above that.
Counting every sponsor, half of 204 studies reached it within 19 months; a quarter within 5 and three quarters within 40.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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