PrP-targeting siRNA Safety & Mechanism Study (PRiSM)

May 7, 2026 updated by: Broad Institute of MIT and Harvard

An Open-label, Single Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Intrathecally Administered PrP-siRNA in Adult Patients Diagnosed With Symptomatic Prion Disease.

The purpose of this trial is to evaluate safety, tolerability, pharmacokinetics and pharmacodynamic impact of PrP-siRNA in symptomatic prion disease patients.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is a first-in-human, open label, single ascending dose study in participants with prion disease. The study will consist of a screening period of up to 2 weeks, administration of a single intrathecal dose of PrP-siRNA, and a 24-week follow-up period. Multiple dose levels will be tested. This trial also includes an observational arm in which participants will not receive investigational drug, and will be followed for an 8-week period after baseline.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Massachusetts General Hospital
        • Principal Investigator:
          • Steven E Arnold, MD
        • Contact:
        • Contact:
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Recruiting
        • Mayo Clinic
        • Contact:
        • Contact:
        • Principal Investigator:
          • Vijay K Ramanan, MD PhD
    • New York
      • New York, New York, United States, 10032
        • Recruiting
        • Columbia University Medical Center
        • Contact:
        • Contact:
        • Principal Investigator:
          • Lawrence Honig, MD PhD
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Recruiting
        • Vanderbilt University Medical Center
        • Contact:
        • Contact:
        • Principal Investigator:
          • Amanda Peltier, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Key inclusion criteria:

  1. clinically manifested symptoms of prion disease, in the opinion of the investigator;
  2. a diagnosis of probable prion disease according to CDC criteria;
  3. a positive CSF RT-QuIC or PRNP genetic test;
  4. no more than moderate functional impairment as quantified by an MRC-PDRS score ≥15; and
  5. availability of a study partner to assist with study procedures.

Key exclusion criteria:

  1. pregnancy;
  2. contraindication to LP; or
  3. recent participation in a different prion disease clinical trial.

Additional inclusion and exclusion criteria apply and will be evaluated at screening.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
No Intervention: Arm 1: Observational
In Arm 1, participants will undergo lumbar punctures and other study activities at baseline (Week 0) and at Week 4 and Week 8. Investigational drug will not be administered. We will prioritize enrollment in Arm 2; Arm 1 will be open to enrollment whenever Arm 2 is not open to enrollment.
Experimental: Arm 2: Single ascending dose
In Arm 2, participants will be admitted to the clinical trial center and receive a single intrathecal dose of PrP-siRNA. Dose levels to be sequentially evaluated are 50, 100, and 200 mg. Patients will be discharged on Day 2 and then periodically return to the study center on an outpatient basis at Week 1, 2, 4, 8, 12 and 24 for safety monitoring and study activities through the 24 week follow up period.
Drug: PrP-siRNA
Intrathecally administered divalent siRNA designed to target the PRNP mRNA. The structure has been published in DOI: 10.1101/2024.12.05.627039
Other Names:
  • 2439-s4
  • 2439-exNA
  • divalent siRNA 2439-exNA

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Frequency of adverse events
Time Frame: Baseline to week 24
Baseline to week 24

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
CSF PrP concentration
Time Frame: 4 weeks post-dose
Prion protein (PrP) concentration in cerebrospinal fluid (CSF), a pharmacodynamic (PD) biomarker for PrP-siRNA activity
4 weeks post-dose
CSF PrP concentration
Time Frame: 8 weeks post-dose
Prion protein (PrP) concentration in cerebrospinal fluid (CSF), a pharmacodynamic (PD) biomarker for PrP-siRNA activity
8 weeks post-dose
CSF PrP concentration
Time Frame: 12 weeks post-dose
Prion protein (PrP) concentration in cerebrospinal fluid (CSF), a pharmacodynamic (PD) biomarker for PrP-siRNA activity
12 weeks post-dose
CSF PrP concentration
Time Frame: 24 weeks post-dose
Prion protein (PrP) concentration in cerebrospinal fluid (CSF), a pharmacodynamic (PD) biomarker for PrP-siRNA activity
24 weeks post-dose
Plasma concentration of PrP-siRNA
Time Frame: 4 hours post-dose
A pharmacokinetic (PK) measurement of investigational drug concentration in plasma
4 hours post-dose
Plasma concentration of PrP-siRNA
Time Frame: 24 hours post-dose
A pharmacokinetic (PK) measurement of investigational drug concentration in plasma
24 hours post-dose
Plasma concentration of PrP-siRNA
Time Frame: 4 weeks post-dose
A pharmacokinetic (PK) measurement of investigational drug concentration in plasma
4 weeks post-dose
CSF concentration of PrP-siRNA
Time Frame: 4 weeks post-dose
A pharmacokinetic (PK) measurement of investigational drug concentration in cerebrospinal fluid (CSF)
4 weeks post-dose
Change in CSF PrP over time
Time Frame: Baseline to week 24
Baseline to week 24

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Broad Institute of MIT and Harvard

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Neurological Disorders and Stroke (NINDS)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Eric V Minikel, PhD, Broad Institute of MIT and Harvard

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

  • Gentile JE, Corridon TL, Serack FE, Echeverria D, Kennedy ZE, Gallant-Behm CL, Hassler MR, Kinberger G, Kamath NG, Lian Y, Gross KY, Miller R, DeSouza-Lenz K, Howard M, Guzman K, Chan N, Curtis DT, Fettes K, Lemaitre M, Cappon G, Jackson AL, Yamada K, Alterman JF, Coffey AA, Minikel EV, Khvorova A, Vallabh SM. Divalent siRNA for prion disease. bioRxiv. 2024 Dec 5;2024.12.05.627039. https://doi.org/10.1101/2024.12.05.627039

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 14, 2029

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 14, 2029

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 24, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 27, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 3, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 7, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NN112
  • OT2NS138339 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

The Broad Institute will share de-identified individual participant data, including biomarker and clinical measurements. Access will be via public dataset release at the time of publication of the study results, or no later than 1 year after the end date of the NIH grant supporting this trial, whichever comes first.

IPD Sharing Time Frame

No later than August 14, 2030 through indefinitely.

IPD Sharing Access Criteria

Publicly released.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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