Natural History of the Progression of Choroideremia Study

Study Overview
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Brief Summary
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The objective of this natural history study is to gain a better understanding of the progression of choroideremia (CHM) and add to the knowledge base for this rare disease.

Detailed Description
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This study was previously posted by NightstaRx Ltd. In October 2020, sponsorship of the trial was transferred to Biogen.

Official Title
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Natural History of the Progression of Choroideremia Study

Conditions
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Choroideremia

Participation Criteria
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Eligibility Criteria
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Key Inclusion Criteria: Are willing and able to provide informed consent for participation in the study. Have a clinical phenotype and confirmed genetic diagnosis of CHM. Have active disease clinically visible within the macular region. Are willing and able to undergo ophthalmic examinations once every 4 months for up to 20 months. Have a BCVA better than or equal to 6/60 (20/200; decimal 0.1; LogMAR 1.0; 34-38 ETDRS letters) in at least one eye. Key Exclusion Criteria: Have a history of amblyopia in the eligible eye. Have any other significant ocular or non-ocular disease/disorder in the eligible eye which, in the opinion of the investigator, may put the subject at risk because of participation in the study, influence the results of the study or influence the subject's ability to participate in the study. Have participated in an interventional research study in the past 6 months. NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Best-Corrected Visual Acuity (BCVA) using the Early Treatment Diabetic Retinopathy Study (EDTRS) | BCVA will be assessed for both eyes using the Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity (VA) chart. BCVA test should be performed prior to pupil dilation, and distance refraction should be carried out before BCVA is measured. Initially, letters are read at a distance of 4 meters from the chart. If <20 letters are read at 4 meters, testing at 1 meter should be performed. BCVA is to be reported as number of letters read correctly by the participant using the ETDRS Scale (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). An increase in the number of letters read correctly means that vision has improved. | Up to Month 20 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from Baseline in Reading Performance using International Reading Speed Texts (IReST) | Reading performance will be evaluated prior to pupil dilation. | Baseline up to Month 12 | 
| Change from Baseline in Color Vision | Colour vision will be tested prior to pupil dilation. Each eye will be tested separately and in the same order. | Baseline up to Month 12 | 
| Change from Baseline in Visual Fields | The progression of defects in visual fields will be assessed in both eyes using perimetry equipment. | Baseline up to Month 12 | 
| Change from Baseline in Contrast Sensitivity | Contrast sensitivity will be measured for both eyes, prior to pupil dilation, using a Pelli Robson chart. | Baseline up to Month 12 | 
| Change from Baseline in Retinal Thinning Using Spectral Domain Optical Coherence Tomography (SD-OCT) | SD-OCT measurements will be performed after dilation of the participant's pupil. | Baseline up to Month 20 | 
| Change from Baseline in Area of Viable Retinal Tissue Using Fundus Autofluorescence | Fundus Autofluorescence will be performed after dilation of the participant's pupil to assess changes in the area of viable retinal tissue. | Baseline up to Month 20 | 
| Change from Baseline in Retinal Sensitivity Using Microperimetry | Macular analyser integrity assessment (MAIA) microperimetry will be conducted for both eyes to assess changes in retinal sensitivity within the macula. | Baseline up to Month 20 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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REP1, Retina, Retinal Degeneration, Retinal Dystrophy, Natural History