A Safety Study of Retinal Gene Therapy for Choroideremia

This is a phase 2 clinical trial of a gene therapy vector made from adenoassociated virus
(AAV) called AAV2-REP1 for the treatment of Choroideremia. Participating subjects will be
required to attend a screening visit during which their suitability for the study will be
assessed, and eligible subjects will undergo a surgical procedure under general anaesthesia
consisting of vitrectomy, retinal detachment and sub-retinal administration of AAV2-REP1.

Subjects will be treated bilaterally, with the interval between eyes determined by discussion
between the investigator and Nightstar. Participating subjects will be required to attend
follow up visits for 12 months following the second eye surgery.

Inclusion Criteria:

1. Are willing and able to give informed consent for participation in the study to have
both eyes treated.

2. Are male and ≥18 years of age.

3. Have a genetically-confirmed diagnosis of CHM.

4. Have active disease clinically visible within the macular region of both eyes.

5. Have a BCVA within certain visual acuity criteria in both eyes

Exclusion Criteria:

1. Have a history of amblyopia or inflammatory disorder in either eye.

2. Are unwilling to use barrier contraception methods, for a period of 3 months following
treatment with AAV2-REP1 in either eye.

3. Have had previous intraocular surgery performed within 3 months of the Screening Visit
in either eye

4. Have any other significant ocular or non-ocular disease/disorder which, in the opinion
of the investigator, may either put the subjects at risk because of participation in
the study, or may influence the results of the study, or the subject's ability to
participate in the study.