Choroideremia Gene Therapy Clinical Trial


Phase II gene therapy study, involving a total of 6 male patients with choroideremia. The study will be conducted at the Bascom Palmer Eye Institute, University of Miami. Patients will be required to attend a total of 11 study visits over a 24 month period with an additional 3 year follow-up.

Full Title of Study: “An Open Label Phase 2 Clinical Trial of Retinal Gene Therapy for Choroideremia Using an Adeno-associated Viral Vector (AAV2) Encoding Rab-escort Protein 1 (REP1)”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: N/A
    • Intervention Model: Single Group Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: February 2018

Detailed Description

This is a Phase II, open label study involving patients with a clinical phenotype of choroideremia and a confirmed CHM genotype. Following consent, patients will be required to attend an initial screening visit (Visit 1). Within 2 weeks of the screening visit patients will undergo a surgical procedure (Visit 2) under general anesthesia which will include a standard vitrectomy, retinal detachment and administration of a subretinal injection of AAV2-REP1 (1×1011 genome particles). Patients will be required to attend a further 9 study visits (Visits 3-11) over a 24 month period for functional, and anatomical assessments as well as monitoring of adverse events. The primary endpoint is the change from baseline in visual acuity in the study eye, compared to control eye. Secondary study endpoints are, change from baseline in autofluorescence evaluation, microperimetry readings and other anatomic and functional outcomes (all in the study eye compared to control eye). Secondary endpoints also include safety assessments to be conducted throughout the study. The fellow eyes of these patients will be utilized as controls in this study and will receive no study treatment.


  • Biological: Injection of AAV2-REP1 (10e11 vg)
    • Single Group: single arm study

Arms, Groups and Cohorts

  • Experimental: Injection of AAV2-REP1
    • Injection of AAV-REP1, 1.00x10e11 vg, subretinal injection of total volume of 100 μL.

Clinical Trial Outcome Measures

Primary Measures

  • Change in Best Corrected Visual Acuity From Baseline
    • Time Frame: Baseline, 24 Months
    • Patients will have an assessment of visual acuity using the Early Treatment of Diabetic Retinopathy Study (ETDRS) vision charts in both eyes. Low Luminance BCVA was measured by placing a 2.0 log unit neutral density filter over the best correction for that eye and having the participant read the normally illuminated ETDRS chart and was reported as the number of letters read correctly (ranging from 0 to 100 letters) in the study eye. The lower the number of letters read correctly on the eye chart, the worse the vision (or visual acuity). The study eye was defined as the eye that met inclusion/exclusion criteria with the worst standard BCVA. If the BCVA in both eyes was similar the Patient determines the worse eye be selected as the study eye. A positive change from baseline indicates an improvement and a negative change from baseline indicates a worsening.

Secondary Measures

  • Change in Retinal Macular Autofluorescence From Baseline
    • Time Frame: 12 and 24 months
    • Measured in mm^2 by Fundus Autofluorescence and shows changes in the integrity and metabolism of retinal cells. A negative change from baseline indicates a decrease in size of the retained retina (worsening; disease progression).
  • Changes in Microperimetry From Baseline
    • Time Frame: Baseline to 24 months
    • Microperimetry assessments. A negative change from baseline indicates disease worsening.
  • Number of Participants Who Experience an Adverse Event
    • Time Frame: 24 months
    • Adverse events during treatment and follow-up period

Participating in This Clinical Trial

Inclusion Criteria

  • 18 Years and older – Male – Able to give informed consent – Genetically confirmed diagnosis of choroideremia – Active disease visible clinically within the macula region – Best-corrected visual acuity equal to or worse than 20/32 but better than or equal to 20/200 in the study eye. Exclusion Criteria:

  • Female – Under the age of 18 – History of amblyopia in the study eye – Men unwilling to use barrier contraception methods – Relevant grossly asymmetrical disease or other ocular morbidity which might confound use of the fellow eye as a long-term control – Any other significant ocular and non-ocular disease/disorder or retinal surgery – Contraindication to use of medications or contrast agents – Participated in research study involving an investigational product in the past 12 weeks – Having had gene or cellular therapy at any time prior to this study.

Gender Eligibility: Male

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Byron Lam
  • Provider of Information About this Clinical Study
    • Sponsor-Investigator: Byron Lam, Professor of Ophthalmology – University of Miami
  • Overall Official(s)

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