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    Clinical Trial Results:
    A Long-term Follow-up Study to Evaluate the Safety and Efficacy of RGX-501

    Summary
    EudraCT number
    		 2019-004496-39
    Trial protocol
    		 NL  
    Global end of trial date
    19 Jul 2024

    Results information
    Results version number
    		 v1(current)
    This version publication date
    25 Jul 2025
    First version publication date
    25 Jul 2025
    Other versions

    Trial information

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    Trial identification
    Sponsor protocol code
    RGX-501-102
    Additional study identifiers
    ISRCTN number
    		 -
    US NCT number
    		 NCT04080050
    WHO universal trial number (UTN)
    		 -
    Sponsors
    Sponsor organisation name
    REGENXBIO INC
    Sponsor organisation address
    9804 Medical Center Dr, Rockville, United States, MD 20850
    Public contact
    Medical Affairs , REGENXBIO INC, medinfo@regenxbio.com
    Scientific contact
    Medical Affairs , REGENXBIO INC, , medinfo@regenxbio.com
    Paediatric regulatory details
    Is trial part of an agreed paediatric investigation plan (PIP)
    No
    Does article 45 of REGULATION (EC) No 1901/2006 apply to this trial?
    No
    Does article 46 of REGULATION (EC) No 1901/2006 apply to this trial?
    No
    Results analysis stage
    Analysis stage
    Final
    Date of interim/final analysis
    19 Jul 2024
    Is this the analysis of the primary completion data?
    Yes
    Primary completion date
    19 Jul 2024
    Global end of trial reached?
    Yes
    Global end of trial date
    19 Jul 2024
    Was the trial ended prematurely?
    No
    General information about the trial
    Main objective of the trial
    The primary objective is to evaluate the long-term safety of RGX-501.
    Protection of trial subjects
    The study was conducted in accordance with the Declaration of Helsinki and with all applicable laws and regulations of the locales and countries where the study was conducted, and in compliance with Good Clinical Practice Guidelines.
    Background therapy
    		 No study drug was administered in this study. All participants have previously received a single IV infusion of RGX-501 in a separate parent clinical study.
    Evidence for comparator
    		 -
    Actual start date of recruitment
    04 Nov 2019
    Long term follow-up planned
    No
    Independent data monitoring committee (IDMC) involvement?
    No
    Population of trial subjects
    Number of subjects enrolled per country
    Country: Number of subjects enrolled
    Netherlands: 2
    Country: Number of subjects enrolled
    United States: 5
    Country: Number of subjects enrolled
    Canada: 1
    Worldwide total number of subjects
    8
    EEA total number of subjects
    2
    Number of subjects enrolled per age group
    In utero
    0
    Preterm newborn - gestational age < 37 wk
    0
    Newborns (0-27 days)
    0
    Infants and toddlers (28 days-23 months)
    0
    Children (2-11 years)
    0
    Adolescents (12-17 years)
    0
    Adults (18-64 years)
    8
    From 65 to 84 years
    0
    85 years and over
    0

    Subject disposition

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    Recruitment
    Recruitment details
    		 Enrollment of each participant occurred the same day or after the participant completed the end of study visit or early termination visit from the previous parent study. Participants were followed in this study cumulatively for up to 5 years after RGX-501 administration or until RGX-501 was commercially available in the participant’s country.

    Pre-assignment
    Screening details
    		 Screen failures were not applicable to this study. Every effort was made to recruit eligible participants in this study on the same day of their EOS visit or ETV from the parent study, or even after the participant has completed the parent study’s EOS visit or ETV.

    Period 1
    Period 1 title
    A Long-Term Follow-up Study (overall period)
    Is this the baseline period?
    		 Yes
    Allocation method
    Not applicable
    Blinding used
    		 Not blinded
    Blinding implementation details
    Not applicable.

    Arms
    Are arms mutually exclusive
    Yes

    Arm title
    		 Cohort 1
    Arm description
    		 The dose levels of RGX-501 vector administered in the parent study were 2.5 × 10^12 GC/kg.
    Arm type
    		 Observational

    Investigational medicinal product name
    RGX-501
    Investigational medicinal product code
    RGX-501
    Other name
    Pharmaceutical forms
    Solution for injection
    Routes of administration
    Intravenous use
    Dosage and administration details
    This was a prospective, observational study to evaluate the long-term safety and efficacy after a single administration of RGX-501. RGX-501 was not administered in this study. Eligible participants were those who had previously enrolled in a parent clinical study (FHGT002) and received a single intravenous (IV) infusion of RGX-501.

    Arm title
    		 Cohort 2
    Arm description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.
    Arm type
    		 Observational

    Investigational medicinal product name
    RGX-501
    Investigational medicinal product code
    RGX-501
    Other name
    Pharmaceutical forms
    Solution for injection
    Routes of administration
    Intravenous use
    Dosage and administration details
    This was a prospective, observational study to evaluate the long-term safety and efficacy after a single administration of RGX-501. RGX-501 was not administered in this study. Eligible participants were those who had previously enrolled in a parent clinical study (FHGT002) and received a single intravenous (IV) infusion of RGX-501.

    Arm title
    		 Expansion Cohort 2
    Arm description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.
    Arm type
    		 Observational

    Investigational medicinal product name
    RGX-501
    Investigational medicinal product code
    RGX-501
    Other name
    Pharmaceutical forms
    Solution for injection
    Routes of administration
    Intravenous use
    Dosage and administration details
    This was a prospective, observational study to evaluate the long-term safety and efficacy after a single administration of RGX-501. RGX-501 was not administered in this study. Eligible participants were those who had previously enrolled in a parent clinical study (FHGT002) and received a single intravenous (IV) infusion of RGX-501.

    Number of subjects in period 1
    		Cohort 1 Cohort 2 Expansion Cohort 2
    Started
    3
    3
    2
    Completed
    1
    3
    2
    Not completed
    2
    0
    0
         Lost to follow-up
    2
    -
    -

    Baseline characteristics

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    Baseline characteristics reporting groups
    Reporting group title
    Cohort 1
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 2.5 × 10^12 GC/kg.

    Reporting group title
    Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Reporting group title
    Expansion Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Reporting group values
    		 Cohort 1 Cohort 2 Expansion Cohort 2 Total
    Number of subjects
    		 3 3 2 8
    Age categorical
    Units: Subjects
        In utero
    		 0 0 0 0
        Preterm newborn infants (gestational age < 37 wks)
    		 0 0 0 0
        Newborns (0-27 days)
    		 0 0 0 0
        Infants and toddlers (28 days-23 months)
    		 0 0 0 0
        Children (2-11 years)
    		 0 0 0 0
        Adolescents (12-17 years)
    		 0 0 0 0
        Adults (18-64 years)
    		 3 3 2 8
        From 65-84 years
    		 0 0 0 0
        85 years and over
    		 0 0 0 0
    Age continuous
    Units: years
        arithmetic mean (standard deviation)
    		 34.6 ( 6.03 ) 32.8 ( 8.94 ) 28.9 ( 1.42 ) -
    Gender categorical
    Units: Subjects
        Female
    		 1 1 1 3
        Male
    		 2 2 1 5

    End points

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    End points reporting groups
    Reporting group title
    Cohort 1
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 2.5 × 10^12 GC/kg.

    Reporting group title
    Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Reporting group title
    Expansion Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Primary: Incidence of AEs and SAEs over time

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    End point title
    		 Incidence of AEs and SAEs over time [1]
    End point description
    The primary endpoints are the incidences of AEs and serious adverse events (SAEs) over time. TEAEs were defined as AEs that started or worsened during or after administration of RGX-501.
    End point type
    Primary
    End point timeframe
    5 years.
    Notes
    [1] - No statistical analyses have been specified for this primary end point. It is expected there is at least one statistical analysis for each primary end point.
    Justification: Descriptive summaries of safety measures are based on observed data. No imputation of missing data were implemented.
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Number of participants affected
        Any TEAEs
    2
    0
    2
        Grade 1 - Mild
    1
    0
    1
        Grade 2 - Moderate
    1
    0
    1
        Grade 3 - Severe
    0
    0
    0
        Grade 4 - Life-threatening
    0
    0
    0
        Grade 5 - Death
    0
    0
    0
        Any RGX-501-related TEAEs
    0
    0
    0
        Any TEAEs of special interest
    0
    0
    0
        Any treatment-emergent SAEs
    2
    0
    0
        Any TEAEs leading to study discontinuation
    0
    0
    0
        Any TEAEs leading to death
    0
    0
    0
    No statistical analyses for this end point

    Secondary: Absolute LDL-C levels by beta quantification

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    End point title
    		 Absolute LDL-C levels by beta quantification
    End point description
    Absolute LDL-C levels by beta quantification at Year 3 after RGX-501 administration.
    End point type
    Secondary
    End point timeframe
    3 years
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from baseline to Year 3 (mg/dL)
        arithmetic mean (standard deviation)
    -145.75 ( 4.596 )
    -74.50 ( 74.246 )
    -155.50 ( 13.435 )
    No statistical analyses for this end point

    Secondary: Absolute total cholesterol over the study duration

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    End point title
    		 Absolute total cholesterol over the study duration
    End point description
    Absolute total cholesterol over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years.
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from Baseline to Year 5 (mg/dL)
        arithmetic mean (standard deviation)
    -228.00 ( 54.991 )
    -77.38 ( 54.313 )
    -422.26 ( 241.084 )
    No statistical analyses for this end point

    Secondary: LDL-C over the study duration

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    End point title
    		 LDL-C over the study duration
    End point description
    LDL-C over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from baseline to Year 5 (mg/dL)
        arithmetic mean (standard deviation)
    -172.00 ( 36.715 )
    -38.20 ( 52.004 )
    -370.51 ( 179.404 )
    No statistical analyses for this end point

    Secondary: Very low density lipoprotein cholesterol (VLDL-C) over the study duration

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    End point title
    		 Very low density lipoprotein cholesterol (VLDL-C) over the study duration [2]
    End point description
    Very low density lipoprotein cholesterol (VLDL-C) over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years.
    Notes
    [2] - The end point is not reporting statistics for all the arms in the baseline period. It is expected all the baseline period arms will be reported on when providing values for an end point on the baseline period.
    Justification: Across all 3 cohorts, limited data are available regarding VLDL-C in the LTFU study for the enrolled population from baseline to the secondary efficacy endpoint. There is only data for a single participant at year 5 timepoint which limits the assessment of change from baseline to the secondary efficacy endpoint timepoints for VLDL-C.
    End point values
    		 Cohort 2
    Number of subjects analysed
    1
    Units: Change from baseline to Year 5 (mg/dL)
        arithmetic mean (standard deviation)
    -22.00 ( 0 )
    No statistical analyses for this end point

    Secondary: High density lipoprotein cholesterol (HDL-C) over the study duration

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    End point title
    		 High density lipoprotein cholesterol (HDL-C) over the study duration
    End point description
    High density lipoprotein cholesterol (HDL-C) over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from baseline to Year 5 (mg/dL)
        arithmetic mean (standard deviation)
    -7.33 ( 4.041 )
    -2.34 ( 2.744 )
    -4.21 ( 10.222 )
    No statistical analyses for this end point

    Secondary: Calculated non-HDL-C over the study duration

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    End point title
    		 Calculated non-HDL-C over the study duration
    End point description
    Calculated non-HDL-C over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years.
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from baseline to Year 5
        arithmetic mean (standard deviation)
    -220.67 ( 54.372 )
    -75.04 ( 51.597 )
    -418.05 ( 230.862 )
    No statistical analyses for this end point

    Secondary: Triglycerides (TG) over the study duration

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    End point title
    		 Triglycerides (TG) over the study duration
    End point description
    Triglycerides (TG) over the study duration, as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years.
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Change from baseline to Year 5 (mg/dL)
        arithmetic mean (standard deviation)
    -50.33 ( 26.407 )
    -36.59 ( 64.176 )
    -52.68 ( 8.598 )
    No statistical analyses for this end point

    Secondary: Lipoprotein a (Lp(a)) over the study duration

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    End point title
    		 Lipoprotein a (Lp(a)) over the study duration [3]
    End point description
    Lipoprotein a (Lp(a)) over the study duration as available from medical records or collected as per standard of care (SOC).
    End point type
    Secondary
    End point timeframe
    5 years.
    Notes
    [3] - The end point is not reporting statistics for all the arms in the baseline period. It is expected all the baseline period arms will be reported on when providing values for an end point on the baseline period.
    Justification: Across all 3 cohorts, limited data were available regarding Lp(a) in the LTFU study for the enrolled population from baseline to secondary efficacy endpoint. Across all 3 cohorts, data were available for only 1 participant in cohort 2 for year 5 which limits the assessment of change from baseline for Lp(a).
    End point values
    		 Cohort 2
    Number of subjects analysed
    1
    Units: Change from baseline to Year 5
        arithmetic mean (standard deviation)
    -184.0 ( 0 )
    No statistical analyses for this end point

    Secondary: Usage of lipid-lowering therapies over time

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    End point title
    		 Usage of lipid-lowering therapies over time [4]
    End point description
    The number of participants who did not resume previously taken or did not initiate any new lipid-lowering treatment over time.
    End point type
    Secondary
    End point timeframe
    5 years
    Notes
    [4] - The end point is not reporting statistics for all the arms in the baseline period. It is expected all the baseline period arms will be reported on when providing values for an end point on the baseline period.
    Justification: Across all 3 cohorts, only 1 (12.5%) participant did not resume previous lipid-lowering therapies and/or initiate new lipid-lowering treatment in the parent and LTFU studies for the enrolled population.
    End point values
    		 Cohort 2
    Number of subjects analysed
    3
    Units: Number of participants
    1
    No statistical analyses for this end point

    Other pre-specified: Summary of healthcare utilization

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    End point title
    		 Summary of healthcare utilization
    End point description
    End point type
    Other pre-specified
    End point timeframe
    5 years.
    End point values
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Number of subjects analysed
    3
    3
    2
    Units: Number of participants
        Any office visits
    3
    3
    2
        Any outpatient procedures
    2
    2
    2
        Any emergency room visits
    2
    0
    2
        Any inpatient hospitalizations
    2
    1
    0
    No statistical analyses for this end point

    Adverse events

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    Adverse events information
    Timeframe for reporting adverse events
    Adverse events are reported throughout the study for 5 years.
    Assessment type
    		 Systematic
    Dictionary used for adverse event reporting
    Dictionary name
    		 MedDRA
    Dictionary version
    23.0
    Reporting groups
    Reporting group title
    Cohort 1
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 2.5 × 10^12 GC/kg.

    Reporting group title
    Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Reporting group title
    Expansion Cohort 2
    Reporting group description
    		 The dose levels of RGX-501 vector administered in the parent study were 7.5 × 10^12 GC/kg.

    Serious adverse events
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Total subjects affected by serious adverse events
         subjects affected / exposed
    2 / 3 (66.67%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         number of deaths (all causes)
    0
    0
    0
         number of deaths resulting from adverse events
    0
    0
    0
    Cardiac disorders
    Angina unstable
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    General disorders and administration site conditions
    Non-cardiac chest pain
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    0 / 0
    Frequency threshold for reporting non-serious adverse events: 1%
    Non-serious adverse events
    		 Cohort 1 Cohort 2 Expansion Cohort 2
    Total subjects affected by non serious adverse events
         subjects affected / exposed
    2 / 3 (66.67%)
    0 / 3 (0.00%)
    2 / 2 (100.00%)
    Injury, poisoning and procedural complications
    Post procedural haemorrhage
         subjects affected / exposed
    0 / 3 (0.00%)
    0 / 3 (0.00%)
    1 / 2 (50.00%)
         occurrences all number
    0
    0
    1
    General disorders and administration site conditions
    Non-cardiac chest pain
         subjects affected / exposed
    0 / 3 (0.00%)
    0 / 3 (0.00%)
    1 / 2 (50.00%)
         occurrences all number
    0
    0
    1
    Peripheral swelling
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    1
    0
    0
    Gastrointestinal disorders
    Toothache
         subjects affected / exposed
    0 / 3 (0.00%)
    0 / 3 (0.00%)
    1 / 2 (50.00%)
         occurrences all number
    0
    0
    1
    Respiratory, thoracic and mediastinal disorders
    Dyspnoea
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    1
    0
    0
    Oropharyngeal pain
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    1
    0
    0
    Psychiatric disorders
    Attention deficit hyperactivity disorder
         subjects affected / exposed
    0 / 3 (0.00%)
    0 / 3 (0.00%)
    1 / 2 (50.00%)
         occurrences all number
    0
    0
    1
    Infections and infestations
    COVID-19
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    2 / 2 (100.00%)
         occurrences all number
    1
    0
    2
    Ear infection
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    1
    0
    0
    Pneumonia
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    1
    0
    0
    Upper respiratory tract infection
         subjects affected / exposed
    1 / 3 (33.33%)
    0 / 3 (0.00%)
    0 / 2 (0.00%)
         occurrences all number
    2
    0
    0

    More information

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    Substantial protocol amendments (globally)
    Were there any global substantial amendments to the protocol? No

    Interruptions (globally)
    Were there any global interruptions to the trial? No

    Limitations and caveats
    Limitations of the trial such as small numbers of subjects analysed or technical problems leading to unreliable data.
    None reported
    For support, Contact us.
    The status and protocol content of GB trials is no longer updated since 1 January 2021. For the UK, as of 31 January 2021, EU Law applies only to the territory of Northern Ireland (NI) to the extent foreseen in the Protocol on Ireland/NI. Legal notice
    As of 31 January 2023, all EU/EEA initial clinical trial applications must be submitted through CTIS . Updated EudraCT trials information and information on PIP/Art 46 trials conducted exclusively in third countries continues to be submitted through EudraCT and published on this website.

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