Gene Therapy for Blindness Caused by Choroideremia


– Primary objective: To assess the safety and tolerability of the AAV.REP1 vector, administered at two different doses to the retina in 12 patients with a diagnosis of choroideremia. – Secondary Objective: To identify any therapeutic benefit as evidenced by a slowing down of the retinal degeneration assessed by functional and anatomical methods in the treated eye compared to the control eye 24 months after gene delivery.

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

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Non-Randomized
    • Intervention Model: Single Group Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: October 2017

Detailed Description

Detailed description may be found in the following scientific publication: Retinal gene therapy in patients with choroideremia: initial findings from a phase 1/2 clinical trial, The Lancet, Volume 383, Issue 9923, Pages 1129 – 1137 (29 March 2014). Links: ;


  • Drug: rAAV2.REP1
    • Single subretinal injection of rAAV2.REP1 vector suspension containing 10e12 genome particles per ml. Dose 1 = dose containing approximately 10e10 rAAV2.REP1 genome particles. Dose 2 = dose containing approximately 10e11 rAAV2.REP1 genome particles.

Arms, Groups and Cohorts

  • Experimental: Dose 1
    • Dose 1 = single subretinal injection of vector suspension containing approximately 10e10 rAAV2.REP1 genome particles. Six patients have now received Dose 1.
  • Experimental: Dose 2
    • Dose 2 = single subretinal injection of vector suspension containing approximately 10e11 rAAV2.REP1 genome particles. Three patients thus far have received Dose 2.

Clinical Trial Outcome Measures

Primary Measures

  • Visual acuity
    • Time Frame: 6 months
    • Best corrected visual acuity, following cataract surgery if indicated

Secondary Measures

  • Microperimetry, OCT and fundus autofluorescence
    • Time Frame: 24 months
    • Structure function correlations at the margins of the retinal degeneration

Participating in This Clinical Trial

Inclusion Criteria

  • Participant is willing and able to give informed consent for participation in the study, – Male aged 18 years or above, – Diagnosed with choroideraemia and in good health, – Active disease with SLO changes visible within the macula region, – Willing to allow his or her General Practitioner and consultant, if appropriate, to be notified of participation in the study, – Vision at least 6/60 or better in the study eye. Exclusion Criteria:

  • Female and child participants (under the age of 18), – Men unwilling to use barrier contraception methods, if relevant, – Previous history of retinal surgery or ocular inflammatory disease (uveitis), – Grossly asymmetrical disease or other ocular morbidity which might confound use of the fellow eye as a long-term control, – Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study, – Participants who have participated in another research study involving an investigational product in the previous 12 weeks.

Gender Eligibility: Male

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of Oxford
  • Collaborator
    • Oxford University Hospitals NHS Trust
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Robert E MacLaren, MB ChB DPhil, Study Chair, University of Oxford, Oxford Radcliffe Hospitals NHS Trust and Moorfields Eye Hospital
    • Miguel C Seabra, MD PhD, Principal Investigator, Imperial College London
    • Andrew R Webster, MD, Principal Investigator, UCL Institute of Ophthalmology and Moorfields Eye Hospital
    • Susan M Downes, MD, Principal Investigator, Oxford University Hospitals NHS Trust
    • Graeme C Black, MB BCh DPhil, Principal Investigator, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust
    • Andrew J Lotery, MD, Principal Investigator, University of Southampton and Southampton University Hospitals Trust
    • Len W Seymour, PhD, Principal Investigator, University of Oxford
    • Tanya Tolmachova, PhD, Principal Investigator, Imperial College London

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