A Gene Therapy Study of RP-A501 in Male Patients With Danon Disease

October 1, 2026 updated by: Rocket Pharmaceuticals Inc.

Gene Therapy for Danon Disease: A Phase 2 Study Evaluating the Efficacy and Safety of Intravenously Administered Adeno-Associated Virus Serotype 9 (rAAV9) Vector Containing the Human LAMP2 Isoform B Transgene (RP-A501; AAV9.LAMP2B) in Male Patients With Danon Disease

This is a single arm Phase 2 trial to evaluate the efficacy and safety of RP-A501, a recombinant adeno-associated virus serotype 9 (rAAV9) vector containing the human lysosome-associated membrane protein 2 isoform B (LAMP2B) transgene, in male patients with Danon disease.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

RP-A501-0123 is a Phase 2 global, multi-center, single arm, open-label, single dose trial in males with Danon disease. The study is designed to assess the efficacy and safety of a single intravenous dose of RP-A501 in treating the cardiomyopathy associated with Danon disease.

RP-A501-0123 will enroll subjects ≥ 8 years of age with a pathogenic or likely pathogenic LAMP2 variant. The trial will include a total of 5 years of follow-up after administration of RP-A501.

Study Type

Interventional

Enrollment (Estimated)

18

Phase

  • Phase 2

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 Locations

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

Ages Eligible for Study

8 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

Key Inclusion Criteria:

  1. Documentation of a pathogenic or likely pathogenic variant of the LAMP2 gene.

  2. Male.

  3. Age ≥8 years.

  4. Evidence of left ventricular hypertrophy with preserved systolic function phenotype as defined by each of the following:

    1. Abnormal thickening of left ventricular wall,
    2. Left ventricular ejection fraction (LVEF) ≥ 50%.
  5. New York Heart Association (NYHA) Class II to III.

  6. High sensitivity Troponin I (hsTnI) ≥20% above the upper limit of normal (ULN) ≤ 12 months prior to screening.

  7. Ability to comply with study procedures including investigational therapy and follow-up evaluations.

Key Exclusion Criteria:

  1. Anti-AAV9 neutralizing antibody titer >1:40.
  2. Severe heart failure or requirement for advanced therapies (requirement for intravenous inotropic, vasodilator, or diuretic therapy within the 30 days prior to enrollment, presence or requirement for mechanical circulatory support (MCS), and presence or requirement for mechanical ventilation).
  3. History of intracardiac thrombosis or arterial thromboembolic events including stroke, transient ischemic attack (TIA), acute coronary syndrome, myocardial infarction or unstable angina.
  4. Prior cardiac or other organ (lung, liver, other) transplantation.

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: RP-A501

A single intravenous infusion of RP-A501 in cohorts of subjects with a confirmed diagnosis of Danon disease.

RP-A501 is a gene therapy product consisting of an rAAV9 capsid containing the human LAMP2B transgene which will be administered as a single IV infusion.

Dose of RP-A501: Cohorts 1, 2 & 3 = 6.7 x10^13 genome copies (GC)/kg; Cohort 4 = 3.8 x10^13 GC/kg.

An immunomodulation regimen is initiated before RP-A501 administration to reduce the risk of gene therapy-related complications. The regimen includes rituximab or a biosimilar, administered in two doses for Cohorts 1-3 and three doses for Cohort 4, along with sirolimus and corticosteroids. Pegcetacoplan was incorporated into the immunomodulation regimen for Cohort 3 but excluded in Cohort 4.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Evaluation of Efficacy: Improvement as assessed via primary endpoint comprised of LAMP2 myocardial tissue expression and left ventricular mass index (LVMI)
Time Frame: 12 months post-infusion

Myocardial tissue expression of LAMP2 protein improved from baseline to ≥ Grade 1 (by IHC), AND, ≥ 10% decrease in LVMI from baseline.

12 months post-infusion

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Evaluation of efficacy via components of the primary endpoint - LAMP2
Time Frame: 12 months post infusion

Myocardial tissue expression of LAMP2 protein improved from baseline to ≥ Grade 1 (by IHC)

12 months post infusion
Evaluation of efficacy via components of the primary endpoint - Left Ventricular Mass Index (LVMI)
Time Frame: 12 months post infusion

≥ 10% decrease in LVMI from baseline

12 months post infusion
Evaluation of efficacy via biomarker evidence of myocardial injury - High Sensitivity Troponin I (hsTnI)
Time Frame: 12 months post infusion

≥ 20% decrease in hsTnI from baseline

12 months post infusion
Evaluation of efficacy via biomarker evidence of myocardial injury - N-Terminal Prohormone of Brain Natriuretic Peptide (NT-proBNP)
Time Frame: 12 months post infusion

≥ 20% decrease in NT-proBNP from baseline

12 months post infusion
Evaluation of efficacy via Quality of Life
Time Frame: 12 months post infusion

Change in KCCQ-12 Overall Score from baseline

12 months post infusion
Evaluation of efficacy via heart failure symptoms
Time Frame: 12 months post infusion

Change in NYHA class from baseline

12 months post infusion
Evaluation of efficacy via assessment of event-free survival
Time Frame: From infusion to 60 months post infusion
  1. Event free survival with events defined as death, heart transplant, mechanical circulatory support (MCS) or heart failure hospitalization
  2. Incidence of death, heart transplant, MCS, or heart failure hospitalization
From infusion to 60 months post infusion
Evaluation of safety
Time Frame: From infusion to 60 months post infusion

Incidence, severity and duration of treatment emergent safety events.

From infusion to 60 months post infusion

Collaborators and Investigators

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

Sponsor

Investigators

  • Principal Investigator: Joseph Rossano, MD, Children's Hospital of Philadelphia
  • Principal Investigator: Barry Greenberg, MD, University of California, San Diego

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 (Actual)

September 5, 2023

Primary Completion (Estimated)

June 1, 2028

Study Completion (Estimated)

June 1, 2032

Study Registration Dates

First Submitted

October 11, 2023

First Submitted That Met QC Criteria

October 17, 2023

First Posted (Actual)

October 23, 2023

Study Record Updates

Last Update Posted (Actual)

October 6, 2026

Last Update Submitted That Met QC Criteria

October 1, 2026

Last Verified

October 1, 2026

More Information

Terms related to this study

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.