A Phase 2 interventional study of Mivelsiran and Placebo in Down Syndrome-Associated Alzheimer's Disease (DS-AD), sponsored by Alnylam Pharmaceuticals. Recruiting at 10 sites in 2 countries. Open to participants aged 40 Years to 55 Years. Per ClinicalTrials.gov, last updated 2026-10-13.
Sponsored by Alnylam Pharmaceuticals · Phase 2, Interventional, and Treatment
The purpose of the study is to evaluate the effect of mivelsiran in adult participants with early-stage DS-AD and to characterize the safety, tolerability, and pharmacodynamics (PD) of mivelsiran. The study will be conducted over 2 periods: a 24-month double-blind period and an optional 12-month open-label treatment extension (OLE) period. The estimated duration of study participation, inclusive of screening, treatment, and additional safety follow-up, is up to 39 months.
438 studies on the registry are indexed under Down Syndrome; 99 are open to participants now.
This study's planned enrollment of 58 is above the median of 37 across 286 interventional studies indexed under Down Syndrome.
Browse Down Syndrome studies →Alnylam Pharmaceuticals is the lead sponsor of 84 studies on the registry; 19 are open to participants now.
Of its 18 completed or terminated interventional studies of FDA-regulated products, 15 (83%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
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.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be administered multiple low doses of mivelsiran.
Drug: Mivelsiran
Participants will be administered multiple high doses of mivelsiran.
Drug: Mivelsiran
Participants will be administered multiple doses of placebo.
Drug: Placebo
Mivelsiran will be administered intrathecally
Also known as: ALN-APP
Placebo will be administered intrathecally
Double-Blind Period: Change from baseline in brain amyloid burden measured in centiloids (CLs)
Time frame: Up to 24 months
Double-Blind Period: Change from baseline in APP protein concentration in cerebrospinal fluid (CSF)
Time frame: Up to 24 months
Double-Blind Period: Change from baseline in the concentration of amyloid beta proteins in CSF
Time frame: Up to 24 months
Double-Blind Period: Change from baseline in the concentration of tau proteins in plasma
Time frame: Up to 24 months
Double-Blind Period: Change from baseline on a cognitive scale
Time frame: Up to 24 months
Double-blind Period and Open-label Extension (OLE) Period: Frequency of adverse events (AEs)
Time frame: Up to 36 months
Plan to share: Yes — Access to Anonymized individual participant data that support these results is made available 12 months after study completion and not less than 12 months after the product and indication have been approved in the US and/or the EU. Access to data may be declined where there is likelihood a patient could be identified or other feasibility issue, where there is a potential conflict of interest, a planned business activities or an actual or potential competitive risk. Data will be provided contingent upon the approval of a research proposal and the execution of a data sharing agreement. Timeframes for data access may vary and can take up to 6 months or more. Requests for access to data can be submitted via the website www.vivli.org. Questions can also be directed to datasharing@alnylam.com.
No publications or documents are linked to this record.
Started Aug 2026 (actual). Primary completion is estimated for May 2030, 45 months after the start.
Of 21 phase 2 interventional studies under Down Syndrome, half reached primary completion within 36 months of starting (the median), counting those still running; a quarter within 26 and three quarters within 61. This study's planned 45 months is above that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Mivelsiran