A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene Therapy for X-linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) Encoding Retinitis Pigmentosa GTPase Regulator (RPGR)
Phase: PHASE1
Conditions: X-Linked Retinitis Pigmentosa
Sponsor: Biogen

COVER PAGE 
Official Title: 
A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) 
Clinical Trial of Retinal Gene Therapy for X-Linked Retinitis 
Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa GTPase Regulator (RPGR) 
NCT Number: 
NCT03116113 
Document Date: 
Protocol Version 11.0: 06 October 2020 
 
 

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TITLE PAGE
CLINICAL STUDY PROTOCOL 
NSR-RPGR-01 / NCT03116113
AAV8-RPGR
A DOSE ESCALATION (PHASE 1), AND DOSE EXPANSION 
(PHASE 2/3) CLINICAL TRIAL OF RETINAL GENE 
THERAPY FOR X-LINKED RETINITIS PIGMENTOSA 
USING AN ADENO-ASSOCIATED VIRAL VECTOR (AAV8) 
ENCODING RETINITIS PIGMENTOSA GTPASE 
REGULATOR (RPGR)
XIRIUS STUDY
INDICATION:
X-linked retinitis pigmentosa
STUDY PHASE:
1/2/3
EUDRACT NUMBER:
2016-003852-60
SPONSOR:
NightstaRx Ltd
2nd Floor
10 Midford Place
London W1T 5BJ UK
Telephone:  +44 (0) 1628 501000
ORIGINAL PROTOCOL DATE: 
27 Sep 2016
VERSION 2: 
01 Dec 2016
VERSION 3: 
26 May 2017
VERSION 4: 
15 Dec 2017
VERSION 5: 
16 Jan 2018 
VERSION 6: 
18 MAY 2018 
VERSION 7: 
16 Nov 2018
VERSION 7.1
10 Dec 2018 (Administrative Amendment)
VERSION 8.0
18 Dec 2018
VERSION 8.1
08 Mar 2019 (Administrative Amendment)
VERSION 9.0
14 Aug 2019
VERSION 10.0
10 Oct 2019
VERSION 11.0
1 Oct 2020
CONFIDENTIALITY STATEMENT
This protocol is the property of Biogen / NightstaRx Ltd. It is not to be transmitted, copied, or published without 
written permission from NightstaRx and must be kept in a confidential manner. Persons to whom the 
information is disclosed must be informed that the information is CONFIDENTIAL and may not be further 
disclosed by them.

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INVESTIGATOR’S SIGNATURE PAGE
Clinical Study Protocol Number:
274RP101 (NSR-RPGR-01)
Protocol Title:
A Dose Escalation (Phase 1), and Dose 
Expansion (Phase 2/3) Clinical Trial of 
Retinal Gene Therapy for X-linked 
Retinitis Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa GTPase 
Regulator (RPGR)
Protocol Date:
1 Oct 2020
I have read the Investigator’s Brochure for AAV8-RPGR and I have read Protocol NSR-
RPGR-01 and agree to conduct the study as outlined and in compliance with the Declaration 
of Helsinki, the International Conference on Harmonisation guideline for Good Clinical 
Practice, and all applicable local and federal regulatory requirements and state/local laws. I 
agree to maintain confidentiality of my subjects and all information received or developed in 
relation to this protocol.
Signed:
Date:
Name
Title
Institution
City, State (as applicable), Country

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CLINICAL RESEARCH ORGANISATION CONTACT INFORMATION
 
 
, UK
Additional contact information is available in the Site Operations Manual. 

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1.
PROTOCOL SYNOPSIS
Name of Sponsor/Company: NightstaRx Ltd
Name of Test Product: AAV8-RPGR
Protocol Title: A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of 
Retinal Gene Therapy for X-linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector 
(AAV8) Encoding Retinitis Pigmentosa GTPase Regulator (RPGR)
Protocol Number: NSR-RPGR-01
Study centers: The study will be conducted at approximately 7 centers across the United Kingdom 
and United States of America
Study period (years): 
Overall study duration: 
Part I: 24 months 
Part II:12 months
Phase of development: Phase 
1/2/3
Study Objective: The objective of the study is to evaluate the safety, tolerability, and efficacy of a 
single sub-retinal injection of AAV8-RPGR in subjects with X-linked retinitis pigmentosa (XLRP).
Endpoints
Part I
Primary Endpoint: 
The primary safety endpoints are the incidence of dose-limiting toxicities (DLTs), and treatment-
emergent adverse events (TEAEs) over a 24-month period. 
Secondary and Exploratory Endpoints:

Change from baseline in microperimetry at 1, 3, 6, 9, 12, 18 and 24 months

Change from baseline in best-corrected visual acuity (BCVA) at 1, 3, 6, 9, 12, 18, and 
24 months

Change from baseline in spectral domain optical coherence tomography (SD-OCT) at 1, 3, 
6, 9, 12, 18 and 24 months

Change from baseline in fundus autofluorescence at 1, 3, 6, 12, 18 and 24 months

Change from baseline in other anatomical and functional outcomes at 1, 3, 6, 9, 12, 18 and 
24 months
Part II
Primary Efficacy Endpoint:
The primary efficacy endpoint is the proportion of study eyes with ≥7 dB improvement from 
baseline at ≥5 of the 16 central loci of the 10-2 grid assessed by Macular Integrity Assessment 
(MAIA) microperimetry at 12 months.
Safety Endpoint:
The safety endpoint is incidence of TEAEs over a 12-month period.
Secondary Endpoints: 

Proportion of study eyes with ≥7 dB improvement from baseline at ≥5 of 16 central loci of 
the 10-2 grid assessed by MAIA microperimetry at 1, 2, 3, 6, and 9 months

Change from baseline in retinal sensitivity at the central 16 loci assessed by MAIA 
microperimetry at 1, 2, 3, 6, 9, and 12 months

Proportion of study eyes with ≥7 dB improvement from baseline at ≥5 of 68 loci of the 
10-2 grid assessed by MAIA microperimetry at 1, 2, 3, 6, 9, and 12 months

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
Change from baseline in retinal sensitivity at 68 loci assessed by MAIA microperimetry at 
1, 2, 3, 6, 9, and 12 months

Change from baseline in best-corrected visual acuity (BCVA) at 1, 2, 3, 6, 9, and 
12 months

Change from baseline in visual field assessed by Octopus 900 perimeter at 3, 6, and 
12 months
Exploratory Endpoints:


 



 
Study Design: This is a Phase 1/2/3, first-in-human, multi-center, dose-escalation interventional 
study of AAV8-RPGR in male subjects with genetically confirmed XLRP. Part I is a dose-
escalation study; Part II is a dose-expansion study, with 2 doses (2.5 × 10^11 vector genomes (vg) 
[high dose], 5 × 10^10 vg [low dose]) selected from Part I based on a benefit/risk assessment, and a 
third untreated group to allow for a controlled comparison of efficacy and safety. 
Part I consists of 11 visits over a 24-month evaluation period. Part II consists of 10 visits over a 12-
month evaluation period. At the Screening / Baseline Visit, each subject will be assessed for 
eligibility of both eyes. Only 1 eye will be randomized (the “study eye”), and the other eye will be 
designated as the “fellow eye”. Selection of the “study eye” will be made on clinical grounds prior 
to randomization and will generally be the worse eye affected.
At the Injection Day Visit (Visit 2, Day 0), subjects will undergo vitrectomy and iatrogenic retinal 
detachment as part of a sub-retinal injection procedure for administration of AAV8-RPGR in their 
study eye. Subjects in the untreated control group will receive study-visit telephone calls to monitor 
AEs/SAEs and review concomitant medications on Visit 2 (Day 0) and on Visits 3 and 4 
(post-operative Days 1 and 7). 
To minimise inflammation resulting from surgery and/or vector/transgene, in Part I, all subjects 
will be given a 21-day course of oral corticosteroid (e.g., prednisolone/prednisone) that will start 
2 days before the planned date of surgery. 
In Part II, all adult subjects will be given a 9-week course of oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, followed by 6 weeks of tapering doses. The dose regimen is 
adjusted for pediatric subjects treated in Part II (see Section 8.8). Subjects may also be treated at 
the time of surgery with up to 1 mL of triamcinolone (40 mg/mL), administered via a deep sub-
Tenon approach. 
Part I: Dose-Escalation Study
Dose escalation part of the study will use a 3+3 escalation scheme (Storer 1989) and will involve 
up to 6 AAV8-RPGR dose cohorts: 5 × 10^9 vg (Cohort 1), 1 × 10^10 vg (Cohort 2), 5 × 10^10 vg 
(Cohort 3), 1 × 10^11 vg (Cohort 4), 2.5 × 10^11 vg (Cohort 5), and 5 × 10^11 vg (Cohort 6). Each 
eligible subject will receive AAV8-RPGR in their study eye and be monitored for DLTs. 
Three to 6 subjects are planned per dose cohort; however, the actual number of subjects enrolled 
into each cohort will depend on the toxicity observed. If no DLTs are observed in the first 
3 subjects treated within a cohort, then escalation to the next dose cohort can proceed. If 1 DLT is 
reported within a 3-subject cohort, an additional 3 subjects will be treated at the same dose. If there 
are no further DLTs reported in the additional 3 subjects, then escalation to the next dose cohort 
can proceed. If ≥2 subjects within a cohort (3 or 6 subjects) have a DLT(s), then the maximum 
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reported within Cohort 1 (3 or 6 subjects), then dosing will cease under this protocol and further 
investigation may occur following a protocol amendment.
An independent Data Monitoring Committee (DMC) will review safety data before confirming 
whether escalation to a higher dose level can occur. There is a potential for surgical complications 
resulting in safety events that meet the criteria for a DLT. In such cases, the DMC will make the 
final adjudication as to whether the event is a DLT. The DMC will review safety data for each 
cohort when at least 3 subjects have been dosed at a particular dose level. However, if 2 subjects 
within a cohort have a DLT(s), dosing will not proceed to subsequent subjects until safety data are 
reviewed by the DMC. For the purpose of making decisions regarding dose escalation, the DMC 
will review safety data collected for at least 4 weeks from each subject in the last dosed cohort. In 
addition, the DMC will review cumulative safety data collected from all previously dosed cohorts 
and take these findings into consideration when making decisions on dose escalation. 
DLTs are defined as any of the following events considered to be related to AAV8-RPGR:

Sustained decrease in BCVA of ≥30 letters on the Early Treatment of Diabetic Retinopathy 
Study (ETDRS) chart compared to baseline; sustained is defined as lasting 48 hours or more 
until recovery, with recovery defined as visual acuity (VA) returning to within 10 letters of 
baseline VA. An exception is made for surgery-related events occurring in close temporal 
association (within <24 hours) of the surgery.

Vitreous inflammation, vitritis (>Grade 3 using standardised Nussenblatt vitreous inflammation 
scale grading) (Nussenblatt, Palestine et al. 1985) 

Any clinically significant retinal damage observed (e.g., retinal atrophy) that is not directly 
attributed to complications of surgery 

Any clinically relevant suspected unexpected serious adverse reaction (as defined in the 
Investigator’s Brochure), with the exception of vision loss or vision-threatening events (as 
defined in Section 11.2.1)
Although the visit will still be considered out-of-window, if subjects are unable to attend the 
24-month visit during the protocol-defined window, they should return to the site to complete this 
visit as soon as it is possible for them to do so; this will be considered their 24-month visit. Delays 
will be identified as protocol deviations (PDs) on a case-by-case basis by the Sponsor based on 
information provided by the site; this will include but is not limited to scenarios such as site 
closure, travel bans, medical travel prohibitions, patient illness, etc.
At study completion, Part I subjects will be invited to participate in a separate long-term follow-up 
study that will collect efficacy and safety data up to 5 years from surgery.
Part II: Dose Expansion 
In Part II, approximately 30 subjects will be randomized 1:1:1 to a high-dose (2.5 × 10^11 vg), a 
low-dose (5 × 10^10 vg), or a third untreated group to allow for a controlled comparison of efficacy 
and safety. Study data will be collected for both eyes of each subject. Since treatment requires an 
invasive surgical procedure under general anesthesia, the sponsor, investigator and the subject will 
be unmasked to the study procedure (i.e., vitrectomy and sub-retinal injection), however within the 
treated groups, the sponsor, investigator and subject will be masked to the assigned dose level. To 
further minimise potential bias of the treated and non-treated eye evaluations, all subjective 
ophthalmic assessments at the Screening/Baseline Visit (Visit 1) and from Month 3 (Visit 6) 
onwards will be conducted by an assessor who is masked to treated eye and treated vs. untreated 
control group.
All Part II subjects will be followed for 12 months with the pre-specified visit schedule.
During Part II, a single administrative interim analysis (IA) may be conducted. If an IA is 
performed, the study will continue as planned in a masked fashion. 
Although the visit will still be considered out-of-window, if subjects are unable to attend the 
12-month visit during the protocol-defined window, they should return to the site to complete this 
visit as soon as it is possible for them to do so. This will be considered their 12-month visit. Delays 
will be identified as PDs on a case-by-case basis by the Sponsor based on information provided by 

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the site; this will include but is not limited to scenarios such as site closure, travel bans, medical 
travel prohibitions, patient illness, etc.
At study completion, treated subjects in Part II will be invited to participate in a separate long-term 
follow-up study that will collect efficacy and safety data up to 5 years from surgery.
Number of subjects (planned): Overall, the study is expected to enroll approximately 48 subjects: 
18 in Part I and up to approximately 30 in Part II. 
Inclusion Criteria: Subjects are eligible for study participation if they meet all the following 
inclusion criteria.
Part I
1.
Subject is willing and able to give informed consent for participation in the study
2.
Are male, ≥18 years of age, and able to comply and adequately perform all study 
assessments
3.
Have a genetically confirmed diagnosis of XLRP (with RPGR mutation)
4.
Have active disease clinically visible within the macular region in both eyes and defined as 
follows:

ellipsoid zone (EZ) on SD-OCT measured at screening, must be within the nasal 
and temporal border of any B-scan, and not be visible on the most inferior and 
superior B-scan
5.
BCVA in both eyes that meets the following criteria, based on the cohort level:

Cohort 1: better than or equal to light perception

Cohorts 2-3: BCVA of 34-73 ETDRS letters (equivalent to worse than or equal to 
6/12 or 20/40 Snellen acuity, but better than or equal to 6/60 or 20/200 Snellen 
acuity).

Cohort 4-6: better than or equal to BCVA of 34 ETDRS letters (equivalent to 
better than or equal to 6/60 or 20/200 Snellen acuity)
Part II
1.
Subject / parent / legal guardian (if applicable) is willing and able to provide informed 
consent/assent for participation in the study
2.
Are male, ≥10 years of age, and able to comply and adequately perform all study 
assessments
3.
Documentation of a pathogenic mutation in the RPGR gene
4.
Have a BCVA in both eyes that meets the following criteria:

Better than or equal to BCVA of 34 ETDRS letters (equivalent to better than or 
equal to 6/60 or 20/200 Snellen acuity).
5.
Mean total retinal sensitivity in the study eye as assessed by microperimetry ≥ 0.1 dB and 
≤8 dB 
Exclusion Criteria: Parts I and II
Subjects are not eligible for study participation if they meet any of the following exclusion criteria:
1.
Have a history of amblyopia in either eye
2.
Are unwilling to use barrier contraception methods (if applicable), or abstain from sexual 
intercourse, for a period of 3 months following treatment with AAV8-RPGR
3.
Have any significant ocular or non-ocular disease/disorder which, in the opinion of the 
investigator, may put the subjects at risk because of participation in the study, may 
influence the results of the study, may influence the subject’s ability to perform study 

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diagnostic tests, or impact the subject’s ability to participate in the study. This would 
include, but is not limited to:
a.
clinically significant cataract
b.
contraindication to oral corticosteroid 
c.
unsuitability for retinal surgery
4.
Have participated in another research study involving an investigational product in the past 
12 weeks or received a gene/cell-based therapy at any time previously (including but not 
limited to: Intelligent Retinal Implant System implantation, ciliary neurotrophic factor 
therapy, nerve growth factor therapy).
Test product, dosage, and mode of administration: Part I, Dose Escalation, Phase 1: All subjects 
will undergo vitrectomy and receive a single sub-retinal injection of AAV8-RPGR. Subjects will be 
assigned to 1 of the following AAV8-RPGR dose levels: 5 × 10^9 vg, 1 × 10^10 vg, 5 × 10^10 vg, 
1 × 10^11 vg, 2.5 × 10^11 vg, or 5 × 10^11 vg. 
Part II, Dose Expansion, Phase 2/3: Subjects will be assigned to 1 of the following: high-dose 
(2.5 × 10^11 vg), low-dose (5 × 10^10 vg), or an untreated control arm.
Reference therapy (Comparator), dosage, and mode of administration: In Part I, no reference 
therapies will be administered. In Part II, 2 doses of AAV8-RPGR will be compared: a high-dose 
(2.5 × 10^11 vg) and a low-dose (5 × 10^10 vg) to an untreated control arm. 
Criteria for Evaluation:
Safety: The safety evaluation will be based on adverse event reporting (including DLTs); full 
ophthalmic examination (including indirect ophthalmoscopy, slit-lamp examination, intraocular 
pressure [IOP], anterior chamber and vitreous inflammation grading and lens opacities 
classification system III [LOCS III] cataract grading); fundus photography; vital signs; and 
laboratory assessments (including laboratory safety parameters, viral shedding and 
immunogenicity).
Any safety information collected as a result of the efficacy assessments (e.g., BCVA) will also be 
used in the overall safety evaluation, as appropriate.
Efficacy: The efficacy evaluation will be based on microperimetry (MAIA), BCVA, SD-OCT, 
fundus autofluorescence, visual fields (Octopus 900 specified in Part II only), contrast sensitivity, 
low luminance visual acuity (LLVA), 
Statistical Methodology:
In Part I, the safety analysis set will include all patients enrolled in the study who received 
AAV8-RPGR treatment.
All analyses in Part I will be performed using the Safety Analysis Set.
In Part II, the Safety Analysis Set will consist of all subjects who are randomized, under both the 2- 
and the 3-arm randomization schemes, and receive study treatment when randomized to active 
treatment, or attend Visit 2 (telephone call) when randomized to control (no treatment). The Safety 
Analysis Set will be used for safety analyses and subjects will be analyzed based on the actual 
treatment received. The efficacy summaries of Part II will be generated using the ‘Intent-to-treat 
(ITT) Analysis Set’. The ITT Analysis Set will include all subjects randomised under the 3-arm 
randomisation scheme. Subjects will be analysed based on the treatment which they were 
randomised to. 
In Part II, a single administrative IA may be conducted. A final analysis will be conducted after all 
subjects complete the Month 12 Visit (or are discontinued). 
Summary statistics will be presented for both eyes (Study Eye and Fellow Eye). Continuous 
variables and their change from baseline will be summarized using descriptive statistics (number of 
subjects [n], mean, standard deviation, median, minimum, maximum, first and third quartiles, fifth 
and ninety-fifth percentiles). Confidence intervals (CI) of the mean and the mean change from 
baseline at each visit maybe be provided, where applicable. For categorical variables, the number 

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and proportion of subjects pertaining to each category will be presented over time, and the CI 
maybe presented where applicable.
The primary endpoint in Part II, i.e., the proportion of study eyes with ≥7 dB improvement of 
retinal sensitivity from baseline at ≥5 out of the 16 central loci, will be compared between 
treatment groups (high dose vs untreated; low dose vs untreated) using the Fisher Exact-Boschloo 
test with a Berger-Boos correction of beta=0.001 (Berger and Boos 1994). The primary hypothesis 
will be tested using Hochberg’s (Hochberg 1988) step-up method with familywise error rate 
controlled at one-sided 0.10. The study will be declared positive if either or both doses achieve 
statistical significance. In addition, the difference in proportions between treatment groups will also 
be presented with its CI calculated by the Miettinen and Nurminen (Miettinen and Nurminen 1985) 
method. 
AEs will be summarized by system organ class and preferred term. Both the number of 
eyes/subjects experiencing an AE and the number of events will be summarized. The serious 
adverse events (SAEs), severity, and relationship to study drug/procedure will be also summarized. 
A by-subject listing of AEs and DLTs will be provided. 

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2.
TABLE OF CONTENTS
TITLE PAGE ................................................................................................................1
SPONSOR APPROVAL PAGE ...................................................................................2
INVESTIGATOR’S SIGNATURE PAGE...................................................................3
CLINICAL RESEARCH ORGANISATION CONTACT INFORMATION..............4
1.
PROTOCOL SYNOPSIS...........................................................................5
2.
TABLE OF CONTENTS.........................................................................11
LIST OF TABLES......................................................................................................14
LIST OF FIGURES.....................................................................................................14
3.
ABBREVIATIONS AND DEFINITIONS..............................................15
4.
INTRODUCTION ...................................................................................17
4.1.
X-linked Retinitis Pigmentosa.................................................................17
4.2.
Molecular Genetics of RPGR ..................................................................17
4.3.
Gene Therapy for Treatment of Retinal Diseases....................................18
4.4.
Rationale for Clinical Development of AAV8-RPGR.............................19
5.
STUDY OBJECTIVES AND ENDPOINTS...........................................21
5.1.
Objective..................................................................................................21
5.2.
Endpoints .................................................................................................21
5.2.1.
Part I.........................................................................................................21
5.2.2.
Part II .......................................................................................................21
6.
INVESTIGATIONAL PLAN..................................................................23
6.1.
Overall Study Design...............................................................................23
6.1.1.
Dose-Limiting Toxicity ...........................................................................24
6.1.2.
Part I: Dose-Escalation Study..................................................................25
6.1.3.
Part II Dose-Expansion, Version 6 ..........................................................26
6.1.4.
Part II: Dose Expansion ...........................................................................26
6.2.
Number of Subjects..................................................................................27
6.3.
Discussion of Study Design and Dose Selection.....................................27
7.
SELECTION AND WITHDRAWAL OF SUBJECTS...........................30
7.1.
Part I.........................................................................................................30
7.1.1.
Inclusion Criteria .....................................................................................30
7.2.
Part II .......................................................................................................30
7.2.1.
Inclusion Criteria .....................................................................................30
7.3.
Exclusion Criteria: Parts I and II .............................................................30
7.4.
Subject Withdrawal Criteria ....................................................................31

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8.
STUDY TREATMENT...........................................................................32
8.1.
Treatments Administered.........................................................................32
8.2.
Description of Study Drug.......................................................................32
8.3.
Packaging, Labeling, Preparation and Storage ........................................32
8.4.
Vitrectomy Procedure and Injection of AAV8-RPGR ............................32
8.5.
Randomisation .........................................................................................34
8.6.
Study Masking .........................................................................................34
8.7.
Study Drug Accountability ......................................................................35
8.8.
Concomitant Therapy...............................................................................35
8.9.
Treatment Compliance.............................................................................37
9.
STUDY VISITS AND PROCEDURES..................................................38
9.1.
Visit 1 (Screening/Baseline Period).........................................................38
9.2.
Visit 2 (Day 0, Surgery/Injection Day Visit)...........................................39
9.3.
Visit 3 (Day 1 Post-Operative Visit)........................................................40
9.4.
Visit 4 (Day 7 Post-Operative Visit ± 3 Days) ........................................41
9.5.
Visit 5 (Month 1 ± 7 Days)......................................................................41
9.6.
Visit 5.9 (Month 2 ± 7 Days)...................................................................42
9.7.
Visit 6 (Month 3 ± 7 Days)......................................................................42
9.8.
Visit 7 (Month 6 ± 14 Days)....................................................................43
9.9.
Visit 8 (Month 9 ± 14 Days)....................................................................44
9.10.
Visit 9 (Month 12 ± 14 Days)..................................................................44
9.11.
Visit 10 (Month 18 ± 14 Days) (Part I Subjects Only)............................45
9.12.
Visit 11 (Month 24 ± 14 Days) (Part I Subjects Only)............................45
9.13.
Early Termination (ET) Visit...................................................................46
9.14.
Unscheduled Visits ..................................................................................47
10.
ASSESSMENT OF EFFICACY..............................................................48
10.1.
Best-Corrected Visual Acuity..................................................................48
10.2.
Spectral Domain Optical Coherence Tomography (SD-OCT)................49
10.3.
Fundus Autofluorescence.........................................................................49
10.4.
MAIA Microperimetry.............................................................................49
10.5.
Visual Field Testing (Perimetry) .............................................................49
10.6.
Contrast Sensitivity..................................................................................50
10.7.
Low Luminance Visual Acuity................................................................50
50
50

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11.
ASSESSMENT OF SAFETY..................................................................51
11.1.
Dose Limiting Toxicity............................................................................51
11.2.
Evaluation, Recording, and Reporting Adverse Events...........................51
11.2.1.
Definitions................................................................................................51
11.2.2.
Recording of Adverse Events ..................................................................52
11.2.3.
Follow-up of Adverse Events ..................................................................53
11.2.4.
Reporting of Serious Adverse Events and Dose-Limiting Toxicities......54
11.2.5.
Procedures for Unmasking.......................................................................54
11.2.6.
Data Monitoring Committee....................................................................54
11.3.
Pregnancy.................................................................................................55
11.4.
Full Ophthalmic Examination..................................................................55
11.5.
Fundus Photography ................................................................................55
11.6.
Vital Signs................................................................................................55
11.7.
Laboratory Assessments ..........................................................................55
11.7.1.
Laboratory Safety Parameters..................................................................55
11.7.2.
Viral Shedding .........................................................................................56
11.7.3.
Immunogenicity Testing..........................................................................56
12.
STATISTICAL CONSIDERATIONS.....................................................57
12.1.
Sample Size..............................................................................................57
12.2.
Procedure for Accounting for Missing Data............................................57
12.3.
Analysis Sets............................................................................................57
12.3.1.
Safety Analysis Set ..................................................................................57
12.3.2.
Intent-to-Treat (ITT) Analysis Set...........................................................57
12.4.
Descriptive Statistics................................................................................58
12.5.
Demographics and Baseline Characteristics............................................58
12.6.
Efficacy Analyses ....................................................................................58
12.6.1.
Multiplicity Adjustment...........................................................................58
12.7.
Safety Analyses........................................................................................59
12.7.1.
Adverse Events ........................................................................................59
12.7.2.
Ocular Safety Evaluations........................................................................59
12.7.3.
Laboratory Assessments and Vital Signs.................................................59
12.8.
Interim Analysis.......................................................................................59
13.
INFORMED CONSENT, ETHICAL REVIEW AND REGULATORY 
CONSIDERATIONS...............................................................................60
13.1.
Informed Consent.....................................................................................60

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13.2.
Ethical/Regulatory Review......................................................................60
13.3.
Regulatory Considerations.......................................................................61
14.
ADMINISTRATIVE PROCEDURES ....................................................62
14.1.
Data Quality Control and Assurance .......................................................62
14.2.
Data Handling and Records Management ...............................................62
14.3.
Access to Source Documentation and Subject Privacy ...........................62
14.4.
End of the Study.......................................................................................63
14.5.
Policy for Publication and Presentation of Data......................................63
15.
REFERENCE LIST .................................................................................64
16.
APPENDICES .........................................................................................69
16.1.
Schedule of Study Procedures .................................................................69
LIST OF TABLES
Table 1
Masked Assessments of Efficacy.............................................................34
Table 2
Laboratory Safety Parameters..................................................................56
Table 3
Schedule of Study Procedures .................................................................70
LIST OF FIGURES
Figure 1
3+3 Dose-Escalation Study......................................................................25
Figure 2
Sub-retinal Injection of AAV8 Vector.....................................................33

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3.
ABBREVIATIONS AND DEFINITIONS
Abbreviation or Term
Definition
AAV
adeno-associated virus
AAV8-RPGR
AAV8 virus particle encapsulating 3.46 kb cDNA for the coRPGR gene
AE
adverse event
BCVA
best-corrected visual acuity
BGH
bovine growth hormone
BSS
balanced salt solution
cDNA
complementary deoxyribonucleic acid
CI
confidence interval
coRPGR
codon optimised human cDNA encoding RPGR
CRC
Central Reading Centre
DLT
dose-limiting toxicity
DMC
Data Monitoring Committee
eCRF
electronic case report form
EDC
electronic data capture 
EMA
European Medicines Agency
ERG
electroretinography
ET
early termination
EZ
ellipsoid zone
ETDRS
Early Treatment of Diabetic Retinopathy Study
FDA
Food and Drug Administration
GCP
Good Clinical Practices
GTMP
gene therapy medicinal product
ICH
International Council for Harmonisation
IEC
Independent Ethics Committee
IA
interim analysis
IOP
intraocular pressure
IRB
Institutional Review Board
ITT
intent to treat
LLVA
low luminance visual acuity
LOCS III
lens opacities classification system III
MAIA
macular integrity assessment
MTD
maximum tolerated dose
ORF15
open reading frame 15
PD
protocol deviation
RP
retinitis pigmentosa 
RPE
retinal pigment epithelium
RPGR
retinitis pigmentosa GTPase regulator
Rpgr
murine homologue of human RPGR
SAE
serious adverse event
SAP
statistical analysis plan

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Abbreviation or Term
Definition
SD-OCT
spectral domain optical coherence tomography
SOP
standard operating procedure
SUSAR
suspected unexpected serious adverse reaction
VA
visual acuity
vg
vector genomes
WT
wild-type
XLRP
X-linked retinitis pigmentosa

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4.
INTRODUCTION
4.1.
X-linked Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a group of hereditary degenerative retinal disorders with 
progressive loss of photoreceptors and accumulation of retinal pigment deposits (Hamel 
2006). Typically, patients ﬁrst experience defective dark adaptation (night blindness), 
followed by worsening of peripheral vision and progressive loss of central vision, often 
leading to legal or total blindness (Petrs-Silva and Linden 2014). RP is generally 
characterized by nyctalopia, constricted visual fields, bone spicule pigmentation of the 
fundus, photoreceptor cell dysfunction and abnormal, diminished or absent a- and b-waves on 
electroretinography (ERG) (Chang, Vaccarella et al. 2011). Fundoscopy generally appears 
normal until progression to mid-stage RP, whereby bone spicule-shaped pigment deposits in 
the mid-periphery, retinal atrophy with narrowing of vessels and moderate pallor of the optic 
nerve become apparent. With end-stage RP, widespread pigment deposits are evident, 
reaching into the macula.
X-linked RP (XLRP) is a very severe form of RP, resulting in rapid disease progression and 
severe retinal dysfunction. The worldwide prevalence of XLRP is approximately 1:30,000 to 
1:40,000 (Tee, Smith et al. 2016). Patients with XLRP typically experience onset of night 
blindness in the first decade, followed by progressive restriction of visual field and loss of 
visual acuity (VA). Most patients are legally blind by the end of the fourth decade.
To date, mutations in the following 3 genes have been identified as causes of XLRP: RP2; 
RP3, also known as the RP GTPase regulator (RPGR) gene; and OFD1 (a rare cause of 
XLRP) (Webb, Parfitt et al. 2012). Approximately 75% of cases of XLRP are due to RPGR 
mutations; the worldwide prevalence of RPGR-associated XLRP is approximately 1:40,000 
to 1:53,000 (Pelletier, Jambou et al. 2007, Shu, McDowall et al. 2008). RPGR protein is 
localized to the photoreceptor-connecting cilium and to the corresponding structures 
(transition zone) in primary cilia. It is involved in different aspects of the ciliary gate, with 
trafficking, sorting of cargoes and quality control of membrane proteins (Ferrari, Di Iorio et 
al. 2011, Megaw, Soares et al. 2015, Tee, Smith et al. 2016). Loss of RPGR function in the 
retina causes the progressive loss of photoreceptors.
Visual loss associated with any retinal disorder is extremely debilitating and significantly 
impacts the patient’s quality of life. XLRP is incurable and treatment is supportive at best. 
There are no currently marketed therapies available for modifying the disease. Possible 
treatments/strategies include light avoidance, neurotrophic factors, retinal implants, electronic 
prostheses, docosahexaenoic acid with or without vitamin A and gene therapy (MacLaren, 
Pearson et al. 2006, Talcott, Ratnam et al. 2011, Zrenner, Bartz-Schmidt et al. 2011, Barry, 
Dagnelie et al. 2012, Wen, Tao et al. 2012, West, Pearson et al. 2012, Zhou, Ni et al. 2012, 
Birch, Weleber et al. 2013, Hoffman, Hughbanks-Wheaton et al. 2014, Hughbanks-Wheaton, 
Birch et al. 2014, Tee, Smith et al. 2016).
A significant unmet medical need exists for new and effective therapies for XLRP, especially 
those designed to halt or significantly reduce the rate of progression.
4.2.
Molecular Genetics of RPGR
The short arm of the X-chromosome harbors RPGR at Xp21.1. The RPGR gene has multiple 
isoforms arising from alternative splicing or post-translational modification (Yan, Swain et 
al. 1998, Kirschner, Rosenberg et al. 1999, Hong and Li 2002, Schmid, Glaus et al. 2010). 
These variants are expressed in different amounts, mainly in the lung, kidney, retina and 

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testes, suggesting tissue-specific splicing with specific functions in different tissues (Schmid, 
Glaus et al. 2010).
The 2 major RPGR isoforms are the constitutive variant encoded by exons 1-19 (RPGREx1-19) 
and the RPGRORF15 isoform, which consists of exons 1-14 of RPGREx1-19 followed by a 
unique C-terminal exon called open reading frame 15 (ORF15; (Tee, Smith et al. 2016)). This 
terminal is a mutational “hot spot”, as it encodes an unusual repetitive sequence of 567 amino 
acids rich in glycine and glutamic acid residues (Vervoort, Lennon et al. 2000, Tee, Smith et 
al. 2016). The RPGRORF15 isoform is only expressed in the retina, with its protein product 
localized to the photoreceptor-connecting cilium (Vervoort, Lennon et al. 2000, Hong and Li 
2002, Mavlyutov, Zhao et al. 2002, Hong, Pawlyk et al. 2003). Mutations in the RPGRORF15 
isoform are responsible for approximately 60% of all cases of XLRP (Vervoort, Lennon et al. 
2000, Bellingrath, Ochakovski et al. 2017). Over 350 RPGR variants have been discovered, 
with more than half occurring in the ORF15 exon, suggesting the importance of this isoform 
in the retina (Fokkema, den Dunnen et al. 2005).
For more information on the molecular genetics of RPGR, refer to the Investigator’s 
Brochure.
4.3.
Gene Therapy for Treatment of Retinal Diseases
Gene therapy is rapidly emerging as a promising approach for the treatment of incurable 
retinal diseases (Bryant, Duker et al. 2012, Boye, Boye et al. 2013). Gene therapy medicinal 
products (GTMPs) are a type of advanced therapy medicinal product, defined as medicines 
derived from genes and cells (EMA 2018). GTMPs contain or consist of recombinant nucleic 
acid delivered via a viral vector to targeted cells. The central goal of gene therapy is to 
replace non-functional or defective genes with new genes that are fully functional so that the 
level of genetic expression can return to normal.
The eye is particularly well suited for gene therapy because of its accessibility, relative 
immune privilege status, small size, compartmentalization and the presence of a fellow eye 
(Boye, Boye et al. 2013). The eye is one of the few relatively immunologically privileged 
sites in the body, so vectors used in gene therapy are unlikely to cause a significant systemic 
immune response. Given the defined volume of the eye, the amount of viral vector needed to 
achieve a therapeutic effect will likely be small, reducing the risk of toxicity and increasing 
the likelihood of being able to manufacture quantities of vector sufficient to treat the retina. 
The eye also allows for localized treatment without intravenous delivery, thus decreasing the 
chance of systemic absorption and toxicity. Finally, the effects of localized ocular treatments 
can be easily observed and monitored for efficacy and safety, something that cannot be 
readily done with systemic conditions (Bryant, Duker et al. 2012).
The most commonly used delivery system for retinal gene therapy is the adeno-associated 
virus (AAV). AAVs remain in the nucleus as episomes with no integration into the human 
genome, thereby decreasing the risk of insertional oncogenesis. AAVs elicit a minimal 
immune response and allow for stable and long-term transgene expression in different retinal 
cells, including photoreceptors, retinal pigment epithelium (RPE) cells, ganglion and Muller 
cells (Vandenberghe, Bell et al. 2011, Day, Byrne et al. 2014).
Numerous early phase clinical trials using AAV vectors are currently underway for potential 
treatment of various retinal diseases, including wet age-related macular degeneration 
(ClinicalTrials.gov Identifier: NCT01024998, NCT01301443), autosomal recessive RP 
(NCT01482195), X-linked retinoschisis, Leber congenital amaurosis (NCT00749957, 
NCT00516477, NCT01208389, NCT00999609), Leber hereditary optic neuropathy 

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(NCT02064569, NCT02652767) Stargardt disease (NCT01367444), achromatopsia 
(NCT02599922), Usher syndrome (NCT01505062, NCT02065011) and choroideremia 
(NCT01461213) (Boye, Boye et al. 2013, MacLaren, Groppe et al. 2014, Edwards, Jolly et al. 
2016).
4.4.
Rationale for Clinical Development of AAV8-RPGR
There has been great interest in developing a GTMP to replace the defective RPGR gene in 
patients with XLRP. When designing a potential GTMP, it is essential to know that the 
transgene meets the packaging limit of the vector. Because the RPGR ORF15 (3.46 kb) is 
within the cloning capacity of standard AAV vectors, and allows space for a choice of 
promoters, an AAV vector is a good candidate for delivery of the RPGR transgene.
Given the instability of the ORF14/15 region of RPGR, development of a stable gene therapy 
construct has proved challenging (Deng, Dyka et al. 2015, Wu, Hiriyanna et al. 2015, 
Pawlyk, Bulgakov et al. 2016). A novel GTMP, AAV8-RPGR (AAV2/8-RK.coRPGR) has 
been developed featuring a codon-optimised coding sequence of RPGRORF15, which stabilizes 
the gene therapy construct and minimizes mutations. Recent studies have shown that the 
codon-optimised RPGR (coRPGR) coding sequence features higher expression-levels than 
wild-type (WT) RPGR. This results in greater sequence stability, provides an identical protein 
product, RPGRORF15, and promotes rod and cone expression (Fischer, McClements et al. 
2017). In these studies, the pharmacodynamic effect of AAV8-RPGR was demonstrated in 
two well-characterized mouse models of XLRP, the transgenic Rpgr-/y model and the 
C57BL/6JRd9/Boc model. The former is a knockout of the entire RPGR gene, whereas the latter 
(Rd9) has a naturally occurring mutation in the ORF15 region; both mice exhibit slow outer 
retinal degeneration. Treatment with 1.5×10^9 vector genomes (vg) AAV8-RPGR appeared 
to be effective in both animal models, as evidenced by an enhanced ERG response compared 
with relevant controls. Further, treatment of C57BL/6JWT mice with 1.5×10^9 vg 
AAV8-RPGR did not lead to toxic ocular effects (Fischer, McClements et al. 2017). Results 
from the sponsor’s toxicity study also indicate that administration of the same vector 
(AAV8-RPGR) is well tolerated in male C57BL/6J mice at dose levels of 1×10^9 and 
3.54×10^9 vg/eye; results from the sponsor’s biodistribution study also support a lack of 
toxicity.
Proof-of-concept has also been demonstrated by other researchers in Rpgr null and Rpgr 
knockout mice using an AAV8 vector encoding RPGRORF15 (Wu, Hiriyanna et al. 2015, 
Pawlyk, Bulgakov et al. 2016). Sustained efficacy was demonstrated up to 18 months 
following a single sub-retinal injection in Rpgr-/y mice, with a dose of 1 × 10^9 vg showing 
the best outcome overall (Wu, Hiriyanna et al. 2015). However, most of the RPGR protein 
expressed in these experiments was truncated, which could have affected protein folding. No 
overt toxicity was observed in Rpgr null mice administered AAV8-RPGR at a lower dose of 
2 × 10^9 vg (Pawlyk, Bulgakov et al. 2016).
In studies conducted with AAV-2/5 vectors encoding RPGRORF15 in two naturally occurring 
canine models (XLPRA1 deletion, XLPRA2 deletion), efficacy was demonstrated up to 
3 years, depending on stage of disease (Beltran, Cideciyan et al. 2012, Beltran, Cideciyan et 
al. 2015). Photoreceptor expression of RPGR was observed after gene transfer, with effective 
preservation of photoreceptor structure and function. These studies lend to the body of 
evidence supporting the development of gene therapy for the treatment of XLRP due to 
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In an ocular study conducted in monkeys, transgene expression following the sub-retinal 
administration of various doses of AAV2 (4 animals [4 eyes/dose]: 10^10 and 10^11) and 
AAV8 (10 animals [5 eyes/dose]: 10^8, 10^9, 10^10, and 10^11) carrying a green fluorescent 
protein transgene correlated with surgical, clinical and immunological observations 
(Vandenberghe, Bell et al. 2011). Both AAV2 and AAV8 demonstrated efficient transduction 
of transgene in the RPE, with AAV8 being markedly better at targeting photoreceptors cells. 
Efficiency of RPE transduction by AAV8 at 10^9 vg was similar to that observed with AAV2 
at a 10-fold higher dose. RPE transduction did not increase linearly at higher doses. Dose-
related immune responses to capsid were observed with each vector, and the highest dose 
(10^11 vg) resulted in retinal inflammation and thinning. Some extra-ocular (lateral 
geniculate nuclei) distribution of vector and transgene was also observed with the highest 
dose. Dose thresholds were identified to effectively deliver gene product to target cells 
without toxicity. The authors concluded that use of AAV8 at intermediate doses (~10^10) is 
likely the best approach for gene therapy trials in humans.
There are very limited published data available with AAV8 dosing in humans for 
ophthalmological indications, although two small studies are ongoing. A Phase 1/2 clinical 
trial sponsored by the National Eye Institute is currently underway to evaluate the safety and 
tolerability of intravitreal AAV-RS1 vector (AAV8-scRS/IRBPhRS) gene transfer to the 
retina of patients with X-linked juvenile retinoschisis (ClinicalTrials.gov Identifier: 
NCT02317887) (doses unspecified). Another Phase 1/2 clinical trial sponsored by STZ eye 
trial is currently underway to evaluate the safety and tolerability of sub-retinal AAV-CNGA3 
vector (rAAV8.hCNGA3) gene transfer to the retina of patients with CNGA3-linked 
achromatopsia (ClinicalTrials.gov Identifier: NCT02610582), using doses between 1 × 10^10 
and 1 × 10^11 vg. Preliminary results from this latter study of subjects dosed with 
1 × 10^10 vg demonstrate acceptable safety (Fischer, Wilhelm et al. 2016), as do higher 
doses of up to 1 × 10^11 vg.
Given these encouraging findings, NightstaRx is developing AAV8-RPGR as a potential 
GTMP for the treatment of XLRP due to mutations in RPGR. Replacing the deficient RPGR 
in XLRP patients with new and viable RPGR is expected to slow or stop retinal degeneration 
and may improve visual function.

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5.
STUDY OBJECTIVES AND ENDPOINTS
5.1.
Objective
The objective of the study is to evaluate the safety, tolerability, and efficacy of a single sub-
retinal injection of AAV8-RPGR in subjects with XLRP.
5.2.
Endpoints
5.2.1.
Part I
5.2.1.1.
Primary Endpoint
The primary safety endpoints are the incidence of dose-limiting toxicities (DLTs), and 
treatment-emergent adverse events (TEAEs) over a 24-month period.
5.2.1.2.
Secondary and Exploratory Endpoints:

Change from baseline in microperimetry at 1, 3, 6, 9, 12, 18 and 24 months

Change from baseline in best-corrected visual acuity (BCVA) at 1, 3, 6, 9, 12, 18, 
and 24 months

Change from baseline in spectral domain optical coherence tomography 
(SD-OCT) at 1, 3, 6, 9, 12, 18 and 24 months

Change from baseline in fundus autofluorescence at 1, 3, 6, 12, 18 and 24 months

Change from baseline in other anatomical and functional outcomes at 1, 3, 6, 9, 
12, 18 and 24 months
5.2.2.
Part II
5.2.2.1.
Primary Efficacy Endpoint
The primary efficacy endpoint is the proportion of study eyes with ≥7 dB improvement from 
baseline at ≥5 of the 16 central loci of the 10-2 grid assessed by Macular Integrity 
Assessment (MAIA) microperimetry at 12 months.
5.2.2.2.
Safety Endpoint
The primary safety endpoint is the incidence of TEAEs over a 12-month period.
5.2.2.3.
Secondary Endpoints 

Proportion of study eyes with ≥7 dB improvement from baseline at ≥5 of 
16 central loci of the 10-2 grid assessed by MAIA microperimetry at 1, 2, 3, 6, 
and 9 months

Change from baseline in retinal sensitivity at the central 16 loci assessed by 
MAIA microperimetry at 1, 2, 3, 6, 9, and 12 months

Proportion of study eyes with ≥7 dB improvement from baseline at ≥5 of 68 loci 
of the 10-2 grid assessed by MAIA microperimetry at 1, 2, 3, 6, 9, and 12 months

Change from baseline in retinal sensitivity at 68 loci assessed by MAIA 
microperimetry at 1, 2, 3, 6, 9, and 12 months

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
Change from baseline in BCVA at 1, 2, 3, 6, 9, and 12 months

Change from baseline in visual field assessed by Octopus 900 perimeter at, 3, 6, 
and 12 months
5.2.2.4.
Exploratory Endpoints 


 



 

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6.
INVESTIGATIONAL PLAN
6.1.
Overall Study Design
This is a Phase 1/2/3, first-in-human, multi-center, dose-escalation interventional study of 
AAV8-RPGR in male subjects with genetically confirmed XLRP. The study will be 
conducted in two parts: Part I is a dose escalation study, Part II is a dose-expansion study, 
with 2 doses selected from Part I based on safety and efficacy, and a third untreated group to 
allow for a controlled comparison of efficacy and safety. 
Part I will identify the maximum tolerated dose (MTD) using a dose-escalation scheme. 
Part II will expand 2 doses, allowing for a broader assessment of the safety and efficacy of 
AAV8-RPGR with a larger sample size, including approximately 30 subjects randomized 
1:1:1 to a high-dose, a low-dose, or an untreated arm. Part I primarily evaluates safety, 
defined by incidence of DLTs and TEAEs over a 24-month period. Part II evaluates safety 
and efficacy, with inclusion of a primary efficacy endpoint, improvement from Baseline in 
microperimetry, evaluated at 12 months, and safety and secondary efficacy evaluated at 1-, 2-
, 3-, 6-, 9-, and 12-months post-treatment.
Under version 6 of the protocol, Part II subjects were to be randomised into 2 active groups 
with a 2:1 allocation ratio (high dose [2.5 × 10^11 vg]: low dose [5 × 10^10 vg]). Any 
subject randomised under this version will be followed for 12 months with the ongoing visit 
schedule and the data will be analysed separately (i.e., included in the Safety Analysis Set but 
not in the Intent-to-Treat Set, See Section 12.3). 
At study completion, all Part I subjects and treated subjects in Part II will be invited to 
participate in a long-term follow-up study that will collect efficacy and safety data up to 
5 years from surgery.
Part I will consist of 11 visits over a 24-month evaluation period. Part II consists of 10 visits 
over a 12-month period. At the Screening/Baseline Visit, each subject will be assessed for 
eligibility of both eyes. Only 1 eye will receive treatment (the “study eye”), and the untreated 
eye will be designated as the “fellow eye.” Selection of the “study eye” will be made on 
clinical grounds and will generally be the worse eye affected. This will be discussed in detail 
and agreed with each subject as part of the informed consent process. Once a subject has been 
randomised, a change in “study eye” designation is not permitted.
At the Injection Day Visit (Visit 2, Day 0), subjects will undergo vitrectomy and iatrogenic 
retinal detachment as part of a sub-retinal injection procedure for administration of 
AAV8-RPGR in their study eye. To minimise inflammation resulting from surgery and/or 
vector/transgene, in Part I, all subjects will be given a 21-day course of oral corticosteroid 
(e.g., prednisolone/prednisone) that will start 2 days before the planned date of surgery (see 
Section 8.8 for details). In Part II, all subjects may be treated at the time of surgery with up to 
1 mL of triamcinolone (40 mg/mL), administered via a deep sub-Tenon approach. Subjects 
will also be given a 9-week course of oral corticosteroid starting 3 days before surgery: 
21 days at 60 mg, followed by 6 weeks of tapering doses. The dose regimen is adjusted for 
pediatric subjects treated in Part II (see Section 8.8). 
Subjects in the untreated control group will receive study-visit telephone calls to monitor 
AEs/SAEs and review concomitant medications on Visit 2 (Day 0) and on Visits 3 and 4 
(post-operative Days 1 and 7).
Subjects will be assessed for safety and efficacy throughout the study as indicated in the 
Schedule of Study Procedures (see Section 16.1). The safety evaluation will be based on the 

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occurrence of adverse event (AE) reporting (including DLTs); full ophthalmic examination 
(including indirect ophthalmoscopy, slit-lamp examination, intraocular pressure [IOP], 
anterior chamber and vitreous inflammation grading and lens opacities classification system 
III [LOCS III] cataract grading); fundus photography; vital signs; and laboratory assessments 
(including laboratory safety parameters, viral shedding and immunogenicity).
The efficacy evaluation will be based on microperimetry, BCVA, SD-OCT, fundus 
autofluorescence, visual fields (Octopus 900 specified in Part II only), contrast sensitivity, 
low luminance visual acuity (LLVA), 
 
. Any safety information collected as a result of the 
efficacy assessments (e.g., BCVA) will also be used in the overall safety evaluation, as 
applicable.
Subjects who develop cataracts may undergo cataract surgery if deemed clinically necessary; 
if surgery is performed, it should be carried out at least 4 weeks before their final visit.
A Part I subject is considered to have completed the study if he completes the Month 24 
assessments. Although the visit will still be considered out-of-window, if Part I subjects are 
unable to attend their final 24-month visit during the protocol-defined window, they should 
return to the site to complete this visit as soon as it is possible for them to do so. Delays will 
be identified as protocol deviations (PDs) on a case-by-case basis by the Sponsor based on 
information provided by the site; this will include but is not limited to scenarios such as site 
closure, travel bans, medical travel prohibitions, patient illness, etc.
A Part II subject is considered to have completed the study if he completes the Month 12 
assessments. Although the visit will still be considered out-of-window, if Part II subjects are 
unable to attend their final 12-month visit during the protocol-defined window, they should 
return to the site to complete this visit as soon as it is possible for them to do so. Delays will 
be identified as PDs on a case-by-case basis by the Sponsor based on information provided 
by the site; this will include but is not limited to scenarios such as site closure, travel bans, 
medical travel prohibitions, patient illness, etc.
During Part II, a single administrative interim analysis (IA) may be conducted. If this IA is 
performed, the study will continue as planned in a masked fashion. 
The end of the study is the date the last subject completes his final-visit assessments, or early 
termination [ET] assessments in the event of premature discontinuation,  or the date of last 
data collection if the last subject is lost to follow-up.
6.1.1.
Dose-Limiting Toxicity
DLTs are defined as any of the following events considered to be related to AAV8-RPGR 
and should be reported to the sponsor:

Sustained decrease in BCVA of ≥30 letters on the Early Treatment of Diabetic 
Retinopathy Study (ETDRS) chart compared to baseline; sustained is defined as 
lasting 48 hours or more until recovery, with recovery defined as visual acuity 
(VA) returning to within 10 letters of baseline VA. An exception is made for 
surgery-related events occurring in close temporal association (within <24 hours) 
of the surgery.

Vitreous inflammation, vitritis (>Grade 3 using standardised Nussenblatt vitreous 
inflammation scale grading) (Nussenblatt, Palestine et al. 1985)

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
Any clinically significant retinal damage observed (e.g., retinal atrophy) that is not 
directly attributed to complications of surgery

Any clinically relevant suspected unexpected serious adverse reaction (as defined 
in the Investigator’s Brochure), with the exception of vision loss or vision-
threatening events (as defined in Section 11.2.1.2)
When triplicate BCVA assessments are performed at screening, the median BCVA result will 
be used for change-from-baseline BCVA computation.
If a DLT occurs at any time during the study, the site is to report the event to the sponsor 
within 24 hours of occurrence. A DLT will be reported by the investigational site, to the 
sponsor via a DLT/serious adverse event (SAE) reporting form that must be completed as 
fully as possible and emailed to 
 within 24 hours of being made aware 
of the event. Only 1 DLT/SAE form must be completed for each DLT.
6.1.2.
Part I: Dose-Escalation Study
The study will use a 3+3 escalation scheme (Storer 1989) for administration of 
AAV8-RPGR; a schematic diagram of the escalation scheme is displayed in Figure 1.
Figure 1
3+3 Dose-Escalation Study
DLT: dose-limiting toxicity; MTD: maximum tolerated dose 
Each dose level and potential DLTs will be reviewed by an independent Data Monitoring Committee. Data 
reviews will occur when at least 3 subjects have been dosed at a particular level or if/when 2 subjects have a 
DLT, whichever comes first. For making decisions regarding dose escalation, the DMC will review safety data 
collected for at least 4 weeks from each subject dosed at a particular level as well as cumulative safety data 
collected from previously dosed cohorts.
Part I of the study will involve up to 6 dose cohorts, with AAV8-RPGR doses of 5 × 10^9 vg 
(Cohort 1), 1 × 10^10 vg (Cohort 2), 5 × 10^10 vg (Cohort 3), and 1 x 10^11 vg (Cohort 4), 
Treat 3 
Subjects
1 Subject Has a 
DLT(s)
2-3 Subjects Have 
a DLT(s)
0 Subjects Have 
a DLT(s)
Escalate to 
next dose
Enter 3 
subjects at 
same dose
Stop 
MTD = Previous dose 
1 of 6 
Subjects 
Have a 
DLT(s)
> 1 of 6 
Subjects Have 
a DLT(s)
Stop 
MTD = Previous dose 

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2.5 × 10^11 vg (Cohort 5), and 5 × 10^11 vg (Cohort 6). Each eligible subject will receive 
AAV8-RPGR in their study eye and will be monitored for DLTs.
An independent Data Monitoring Committee (DMC) will be used to review safety data 
before confirming whether escalation to a higher dose level can occur. There is a potential for 
surgical complications resulting in safety events that meet the criteria for a DLT. In such 
cases, the DMC will make the final adjudication as to whether the event is a DLT.
The DMC will review safety data for each cohort when at least 3 subjects have been dosed at 
a particular level. However, if 2 subjects within a cohort have a DLT(s), dosing will not 
proceed to subsequent subjects until safety data are reviewed by the DMC.
For making decisions regarding dose escalation, the DMC will review safety data collected 
for at least 4 weeks from each subject in the last dosed cohort. In addition, the DMC will 
review cumulative safety data collected from all previously dosed cohorts and take these 
findings into consideration when making decisions on dose escalation.
There will be a minimum of 4 weeks between each subject dosed in Cohort 1. Unless 
otherwise specified by the DMC, there will be no restrictions on the interval between subjects 
being dosed in Cohort 2 onwards.
Three to 6 subjects are planned per dose cohort; however, the actual number of subjects 
enrolled into each cohort will depend on the toxicity observed. If no DLTs are observed in 
the first 3 subjects treated within a cohort, then escalation to the next dose cohort can 
proceed. If 1 DLT is reported within a 3-subject cohort, an additional 3 subjects will be 
treated at the same dose. If there are no further DLTs reported in the additional 3 subjects, 
then escalation to the next dose cohort can proceed. If ≥2 subjects within a cohort (3 or 
6 subjects) have a DLT(s), then the maximum tolerated dose (MTD) will be identified as the 
previous (lower) dose. If ≥2 subjects with a DLT are reported within Cohort 1 (3 or 
6 subjects), then dosing will cease under this protocol and further investigation may occur 
following a protocol amendment.
Although the visit will still be considered out-of-window, if Part I subjects are unable to 
attend their final 24-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 24-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited to 
scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
6.1.3.
Part II Dose-Expansion, Version 6 
Under version 6 of the protocol, Part II subjects were to be randomised into 2 active groups 
with a 2:1 allocation ratio (high dose [2.5 × 10^11 vg]: low dose [5 × 10^10 vg]). Any 
subject randomised under this version will be followed for 12 months with the ongoing visit 
schedule and the data will be analysed separately  (i.e., included in the Safety Analysis Set 
but not in the Intent to Treat Set, See Section 12.3). 
Enrollment under Version 6.0 has been superseded by the 3-arm randomisation ongoing since 
Version 7. 
6.1.4.
Part II: Dose Expansion  
From version 9.0 thereafter, approximately 30 additional subjects will be randomized in a 
1:1:1 allocation ratio to a high-dose group (2.5 × 10^11 vg), a low-dose group (5 × 10^10 vg), 
and an untreated group. 

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Study data will be collected for both eyes of each subject. Since treatment requires an 
invasive surgical procedure under general anesthesia, the sponsor, investigator and the 
subject will be unmasked to the study procedure (i.e., vitrectomy and sub-retinal injection), 
however within the treated groups, the sponsor, investigator and subject will be masked to the 
assigned dose. To further minimise potential bias of the treated and non-treated eye 
evaluations, all subjective ophthalmic assessments at the Screening/Baseline Visit (Visit 1) 
and from Month 3 (Visit 6) onwards will be conducted by a masked assessor.
During Part II, a single administrative IA may be conducted. If this IA is performed, the 
study will continue as planned in a masked fashion. A final analysis will be conducted at the 
end of the study, i.e., after all subjects complete the study. The end of the study is defined as 
the date the last subject completes his final-visit assessments, or early termination [ET] 
assessments in the event of premature discontinuation, or the date of last data collection if the 
last subject is lost to follow-up. See Section 12.8 for further details.
Although the visit will still be considered out-of-window, if Part II subjects are unable to 
attend their final 12-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 12-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited to 
scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
6.2.
Number of Subjects
Overall, the study is expected to enroll approximately 48 subjects: 18 in Part I and 
approximately 30 in Part II under 1:1:1 randomization scheme. See Section 12.1 for rationale. 
6.3.
Discussion of Study Design and Dose Selection
Guidelines published by the EMA and Food and Drug Administration (FDA) on mitigating 
risks in first-in-human studies and use of gene therapy in clinical trials were used in the 
design of this study (EMA 1994, EMA 2007, FDA 2015, EMA 2016, EMA 2018). An 
independent DMC will be used to review safety data before any dose escalation decisions are 
made.
The subjects to be included in the study are representative of active XLRP disease and are 
being selected to optimize observance of meaningful change in the outcome measures. The 
planned sample size in Part I is consistent with a 3+3 escalation scheme. A prospective trial 
period of 24 months for Part I is considered to be a sufficient period of time to monitor for 
any AEs related to the vector and/or transgene/administration procedure. 
The starting dose being used in this clinical study is 5 × 10^9 vg AAV8-RPGR. This dose is 
primarily based on human equivalent doses (calculated on the basis of vitreous volume) from 
the AAV8-RPGR 26-week single-dose toxicity and biodistribution studies conducted by the 
sponsor and the mouse studies conducted at the University of Oxford (Fischer, McClements 
et al. 2017). In the Fischer studies, treatment with 1.5 × 10^9 vg AAV8-RPGR did not lead to 
toxic ocular effects in C57BL/6JWT. Results from the sponsor’s toxicity and biodistribution 
studies indicate that AAV8-RPGR is well tolerated in male C57BL/6J mice at dose levels of 
1 × 10^9 vg/eye and 3.54 × 10^9 vg/eye. The NOAEL was determined to be 
3.54 × 10^9 vg/eye in mice, providing a 700-fold safety margin compared to the starting 
dose.
The second and third dose levels in this study are 1 × 10^10 and 5 × 10^10 vg. These dose 
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1 × 10^10 vg respectively), considering the possibility of a narrow safe range for RPGR 
expression. Smaller dose increments were not expected to add meaningful information. 
Further, in a monkey study, dose thresholds of AAV8-GFP (an AAV8 virus particle encoding 
green fluorescence protein) were identified to effectively deliver gene product to target cells 
without toxicity, with the highest safe dose identified as 1 × 10^10 vg (Vandenberghe, Bell et 
al. 2011). In an ongoing Phase 1/2 clinical trial evaluating the safety and tolerability of sub-
retinal AAV-CNGA3 vector (rAAV8.hCNGA3) in patients with CNGA3-linked 
achromatopsia, patients receive vector at doses between 1 × 10^10 and 1 × 10^11 vg 
(ClinicalTrials.gov Identifier: NCT02610582). Preliminary results from this clinical study in 
subjects dosed with 1 × 10^10 vg demonstrate acceptable safety (Fischer, Wilhelm et al. 
2016), as do higher doses of up to 1 × 10^11vg.
The fourth (1×10^11 vg), fifth and sixth (2.5 × 10^11 and 5 × 10^11 vg) dose levels are less 
than a 0.5- log increase from the previous dose levels, ensuring a more conservative approach 
at the upper end of the dose-exploration range. The NOAEL in mice provides a 7-fold safety 
margin compared to the clinical maximum dose (5 × 10^11 vg).
Further details are provided in the Investigator’s Brochure.Given previous experience 
demonstrating the safety of higher subretinal doses of AAV8 vector (Vandenberghe, Bell et 
al. 2011), and lacking safety signals at the lower range of doses, it should be possible to dose-
escalate to the high end of the dose range of AAV8-RPGR.
Application of AAV8-RPGR to the under-surface of the retina requires retinal detachment 
following vitrectomy. As such, sub-retinal injection of AAV8-RPGR carries the risks 
associated with vitrectomy and retinal detachment, which include intra-operative and post-
operative complications: infection (most notably infectious endophthalmitis); low and 
elevated IOP; choroidal detachment; macular oedema; vitreous haemorrhage; visual 
impairment; metamorphopsia; and photopsia (Park, Marcus et al. 1995, Thompson, Sjaarda et 
al. 1996, Banker, Freeman et al. 1997, Cheng, Azen et al. 2001, Anderson, Fineman et al. 
2006, Stein, Zacks et al. 2009, Recchia, Scott et al. 2010). Post-operative intraocular 
inflammation caused by vitrectomy is often associated with transient visual impairment. A 
long-term complication of vitrectomy is cataract formation, which may require an additional 
surgical procedure (cataract extraction) (Park, Marcus et al. 1995, Cheng, Azen et al. 2001, 
Recchia, Scott et al. 2010). To minimise inflammation resulting from potential immune 
responses to vector, subjects receiving AAV8-RPGR will be given a course of oral 
corticosteroid (see Section 8.8 for details). 
Once Part I dose-escalation has been completed, and the safety and tolerability of 
AAV8-RPGR is demonstrated in adults, subjects ≥10 years of age will be enrolled in Part II 
of the study. The 10-years of age cut-off safeguards that participating pediatric subjects will 
be able to comply, adequately perform study assessments, and have sufficiently advanced 
disease that is encroaching on the macula (i.e., the AAV8-RPGR treatment administration 
area).
In Part II, subjects will be randomized to a high-dose (2.5 × 10^11 vg), a low-dose 
(5 × 10^10 vg), and an untreated group. This allows for comparisons in a randomized and 
controlled fashion, as recommended by regulators for best practices in ophthalmic gene 
therapy studies (FDA 2018). The sponsor, investigator and the subject will be unmasked to 
the study procedure and treatment (i.e. vitrectomy and sub-retinal injection). However, within 
the treated groups, the sponsor, investigator, and subject will be masked (i.e. double-masked) 
to the assigned dose. To further minimise potential bias of the treated and non-treated eye 

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evaluations, all subjective ophthalmic assessments at the Screening/Baseline Visit (Visit 1) 
and from Month 3 (Visit 6) onwards will be conducted by a masked assessor.

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7.
SELECTION AND WITHDRAWAL OF SUBJECTS
7.1.
Part I
7.1.1.
Inclusion Criteria
Subjects are eligible for study participation if they meet all the following inclusion criteria.
1. Subject is willing and able to provide informed consent for participation in the study
2. Are male, ≥18 years of age, and able to comply and adequately perform all study 
assessments
3. Have a genetically confirmed diagnosis of XLRP (with RPGR mutation)
4. Have active disease clinically visible within the macular region in both eyes and 
defined as follows:
ellipsoid zone (EZ) on SD-OCT measured at screening, must be within the 
nasal and temporal border of any B-scan, and not be visible on the most 
inferior and superior B-scan
5. Have a BCVA in both eyes that meets the following criteria, based on the cohort 
level:

Cohort 1: better than or equal to light perception

Cohorts 2-3:  BCVA of 34-73 ETDRS letters (equivalent to worse than or 
equal to 6/12 or 20/40 Snellen acuity, but better than or equal to 6/60 or 
20/200 Snellen acuity).

Cohort 4-6: better than or equal to BCVA of 34 ETDRS letters (equivalent 
to better than or equal to 6/60 or 20/200 Snellen acuity).
7.2.
Part II
7.2.1.
Inclusion Criteria
1. Subject / parent / legal guardian (if applicable) is willing and able to provide informed 
consent/assent for participation in the study
2. Are male, ≥10 years of age, and able to comply and adequately perform all study 
assessments
3. Documentation of a pathogenic mutation in the RPGR gene
4. Have a BCVA in both eyes that meets the following criteria:

Better than or equal to BCVA of 34 ETDRS letters (equivalent to better than or 
equal to 6/60 or 20/200 Snellen acuity).
5. Mean total retinal sensitivity in the study eye as assessed by microperimetry ≥0.1 dB 
and ≤8 dB
7.3.
Exclusion Criteria: Parts I and II
Subjects are not eligible for study participation if they meet any of the following exclusion 
criteria:
1. Have a history of amblyopia in either eye

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2. Are unwilling to use barrier contraception methods (if applicable), or abstain from 
sexual intercourse, for a period of 3 months following treatment with AAV8-RPGR 
3. Have any other significant ocular or non-ocular disease/disorder which, in the opinion 
of the investigator, may put the subjects at risk because of participation in the study, 
may influence the results of the study, may influence the subject’s ability to perform 
study diagnostic tests, or impact the subject’s ability to participate in the study. This 
would include, but is not limited to, the following: 
a.
clinically significant cataract
b. contraindication to oral corticosteroid
c.
unsuitability for retinal surgery
4. Have participated in another research study involving an investigational product in the 
past 12 weeks or received a gene/cell-based therapy at any time previously (including, 
but not limited to, Intelligent Retinal Implant System implantation, ciliary 
neurotrophic factor therapy, nerve growth factor therapy).
7.4.
Subject Withdrawal Criteria
Each subject has the right to withdraw from the study at any time without prejudice. In 
addition, the investigator may discontinue a subject from the study at any time if the 
investigator considers it necessary for any reason, including:

Significant protocol deviation

Significant non-compliance with study requirements

AE which results in an inability to continue to comply with study assessments

Lost to follow up

Death

Other (to be specified on the electronic case report form [eCRF]).
If a subject discontinues the study, the reason for withdrawal is to be recorded in the eCRF. 
In the event that a subject discontinues the study early, the site should use every reasonable 
effort to ensure that an ET Visit is conducted as outlined in the Schedule of Study Procedures 
(see Section 16.1). If the subject is withdrawn due to an AE, the investigator will arrange for 
follow-up until the event has resolved or stabilized. For subjects who withdraw 
consent/assent, data will be collected through their last available study visit. 
Withdrawal from the study will not result in the exclusion of a subject’s data acquired up to 
the point of withdrawal. 
The study may be discontinued if the Sponsor deems it necessary for medical, safety, 
regulatory or other reasons consistent with applicable laws or regulations.

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8.
STUDY TREATMENT
8.1.
Treatments Administered
Part I, Dose Escalation, Phase 1: all subjects will undergo vitrectomy and retinal detachment 
in their study eye and then receive a single, sub-retinal injection of AAV8-RPGR (See 
Section 8.4 for details). Subjects will receive an AAV8-RPGR dose of 5 × 10^9 vg 
(Cohort 1), 1 × 10^10 vg (Cohort 2), 5 × 10^10 vg (Cohort 3), 1 x 10^11 vg (Cohort 4), 
2.5 × 10^11 vg (Cohort 5), or 5 x 10^11 vg (Cohort 6). See Section 6.1.2 for details.
Part II, Dose Expansion, Phase 2/3: Subjects will be assigned to 1 of the following: high-dose 
(2.5 × 10^11 vg), low-dose (5 × 10^10 vg), or an untreated control arm.
8.2.
Description of Study Drug
The drug substance is the AAV8 vector containing recombinant human complementary 
deoxyribonucleic acid (cDNA) encoding RPGR (AAV8-RPGR). The vector genome 
(AAV8-coRPGR-BGH, known as AAV8-RPGR) is comprised of a strong constitutive 
expression cassette, a rhodopsin kinase promoter, the codon-optimised human cDNA 
encoding RPGR (coRPGR), and a bovine growth hormone (BGH)-polyA sequence flanked 
by AAV2 inverted terminal repeats. The codon-optimised human coding sequence of the 
retina-specific isoform RPGRORF15 was synthesized; the WT sequence of RPGRORF15 was 
also synthesized and provided in a pCMV6-XL vector backbone or in a pUC57 vector 
backbone for cloning. 
The AAV8-RPGR drug product is formulated in a sterile, 20 mM Tris-buffered solution, 
pH 8.0, and contains 1 mM MgCl2, 200 mM NaCl, and 0.001% Pluronic F-68 (PF68). The 
drug product is a clear to slightly opalescent, colorless, sterile-filtered suspension with a 
target concentration of 5 × 10^12 vg/mL.
8.3.
Packaging, Labeling, Preparation and Storage
AAV8-RPGR will be supplied in labelled sterile polypropylene tubes, with each tube 
containing 0.3 mL vector suspension. Thus, each tube will contain 1.5 × 10^12 vg in total.
AAV8-RPGR will be delivered in a total volume of up to 0.1 mL. Instructions for preparation 
and dilution of drug product to deliver the desired dose of AAV8-RPGR will be provided in 
the pharmacy manual.
Prior to shipment, each vial will be placed in a labelled secondary container. The drug 
product is to be stored at <−60oC (<−76oF) in a controlled access, temperature monitored 
freezer.
The Investigational Medicinal Product (IMP) will be labelled in compliance with regulatory 
standards.
8.4.
Vitrectomy Procedure and Injection of AAV8-RPGR
The subretinal injection technique to be used in this study is similar to that developed in the 
sponsor’s choroideremia programme in Oxford and other international investigator-sponsored 
trials in the United States, Canada and Germany. To date, over 200 subjects have been 
injected without complication by retinal surgeons using the technique described below.
All subjects may be treated at the time of surgery with up to 1 mL of triamcinolone 
(40 mg/mL), administered via a deep sub-Tenon approach.

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Injection of AAV8-RPGR is to be performed by an appropriately qualified and experienced 
retinal surgeon. All surgeons must have completed all study-specific surgical training and 
obtained certification by NightstaRx to perform the study procedure, before treating a study 
participant.
Initially, subjects will undergo a standard vitrectomy and detachment of the posterior hyaloid 
(Figure 2). All surgery will be conducted using the standard BIOM vitrectomy system. A 
23-gauge sutured approach is usually favored to avoid any potential risks of wound leakage. 
Prior to sub-retinal injection of AAV8-RPGR, the retina will be detached with 0.1-0.5 mL of 
balanced salt solution (BSS) injected through a 41-gauge sub-retinal cannula connected to a 
vitreous injection set. A single dose of AAV8-RPGR will be injected into the sub-retinal fluid 
through the same entry site. If detachment of the macula occurs with a smaller volume of 
fluid, then additional subretinal sites in the posterior globe (e.g., nasal to the disc) may also 
be chosen to deliver up to the entire 0.1 ml of vector. This avoids excessive foveal stretch.
If unexpected complications of retinal detachment are encountered (e.g., macular hole created 
requiring treatment with gas), the injection of vector can be deferred until a later date.
Subjects will be carefully monitored for the occurrence of AEs peri- and post-operatively. All 
AEs, irrespective of relationship to the study drug and/or the surgical procedure will be 
captured in the subject’s medical record and reported in the eCRF.
Figure 2
Sub-retinal Injection of AAV8 Vector
A
B
(A) A standard vitrectomy through the BIOM operating system to remove the vitreous gel is followed by (B) 
retinal detachment by injection of BSS and injection of up to 0.1 mL vector suspension through a 41-gauge 
cannula into the sub-retinal space.

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8.5.
Randomisation
Part I, the dose-escalation portion of this study, is open-label and not randomized. 
In Part II, after the study eye is assigned, subjects will be randomised to 1 of 3 groups with a 
1:1:1 allocation ratio: 1) treatment with AAV8-RPGR at a high dose (2.5 × 10^11 vg); 
2) treatment with AAV8-RPGR at a low dose (5 × 10^10 vg) or 3) no treatment. Once a 
subject has been randomized, a change in “study eye” designation is not permitted. 
Randomisation will be generated using a validated system that automates the random 
assignment of treatment groups to randomisation numbers. Once a subject is deemed eligible, 
the investigative site (or authorized designee) will access the system, and the subject will be 
randomised using a standard blocked randomisation. The randomisation number will include 
the center number and subject number.
8.6.
Study Masking
Part I of the study is open label.
Part II is double-masked (subject, surgeon, investigator/site team, and sponsor will be 
masked) to the assigned dose, and open-label with respect to the treatment procedure.
In Part II, ophthalmic assessments that will be used as efficacy endpoints (BCVA, LLVA, 
microperimetry, contrast sensitivity 
) will be conducted by appropriately 
qualified assessors (see Table 1). For the immediate post-operative visits, masking of the 
assessors will not be viable as clinical signs of surgery will be apparent (i.e., redness, 
swelling). Therefore, unmasked assessors will perform all ophthalmic assessments at Visit 3 
(Day 1), Visit 4 (Day 7), Visit 5 (Month 1), and Visit 5.9 (Month 2). From Visit 6 (Month 3) 
onwards, masked assessors will be used, as signs of surgery will have dissipated and it should 
not be possible clinically to differentiate between those subjects that have not undergone 
surgery, and those subjects that have undergone surgery and received active treatment. It is 
preferable that the same assessor who performed the efficacy endpoint assessments at 
Screening/Baseline also perform the assessments during the masked period from Month 3 to 
Month 12. 
Table 1
Masked Assessments of Efficacy 
Masked Assessments at Month 3, 6, 9 and 12 Post-Treatment with AAV8-RPGR

Best-corrected visual acuity

Low-luminance visual acuity

Microperimetry

Contrast sensitivity

Subjects randomised to the untreated Control group will not be required to attend the site at 
Visit 2, 3 or 4. As the key purpose of Visit 2 is surgery, and Visit 3 and 4 are post-operative 
safety visits, there is limited utility in Control subjects attending. Therefore, to limit the study 
burden for Control subjects thereby potentially reducing the risk of subject withdrawal at this 
stage and reducing the possibility of further unmasking due to direct contact and 
communication with fellow participants, Control subjects are not scheduled to attend the 
clinic for study visits at these times.
To minimise bias further, masked assessors will not have access to the subject’s medical 
records, source documentation or eCRF as data entries or notation (such as use of peri-

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operative corticosteroid) may be sources of unmasking. From Visit 6 (Month 3) onwards, the 
masked assessor will also read a pre-written statement to each subject, regardless of 
randomisation, reminding them of the masked nature of the study, and to avoid any reference 
to prior surgery/non-surgery, which eye may have received treatment or to allude to any 
information that may unmask the assessor as to which group the subject has been assigned to. 
Furthermore, it is anticipated that a subset of the subjects participating in the trial will be 
active on social media. Following appropriate approval by the Independent Ethics Committee 
(IEC)/Institutional Review Board (IRB), the patient information leaflet will request that 
subjects refrain from posting any details of study participation on social media, that may 
unmask the assessors to the group the subject has been assigned to. This request will be 
reiterated at subject visits by the investigator and within the pre-written statement.
Subjects randomised to the AAV8-RPGR treatment groups, surgeons, the investigative team, 
and the study sponsor will be masked to which dose of AAV8-RPGR the subject has been 
assigned to. Unmasked study site personnel will be assigned the responsibility of performing 
dilution, which will take place in a designated area remote from the investigative team to 
preserve masking of the treatment arm. Personnel delegated to perform the dilution will not 
be involved in any other aspect of the study (i.e., consent, safety/efficacy assessments, 
surgical procedure).
During Part II, a single administrative IA may be performed. If this IA is performed, the 
study will continue as planned in a masked fashion. 
8.7.
Study Drug Accountability
Records of the receipt and dispensing of study drug will be kept by each study center until the 
end of the study to provide complete accounting of all used and unused study drug. 
Dispensation logs will be checked by the Sponsor (or its designee). Study centers will destroy 
all used vials in accordance with local procedures and will return all unused study drug to the 
Sponsor (or its designee) at the end of the study. Final drug accountability will be verified by 
the Sponsor (or its designee).
8.8.
Concomitant Therapy
Subjects cannot have participated in another research study involving an investigational 
product in the past 12 weeks or received a gene/cell-based therapy at any time previously 
(including, but not limited to, IRIS implantation, ciliary neurotrophic factor therapy, nerve 
growth factor therapy).
Throughout the study, subjects may be prescribed any concomitant medications, procedures 
and/ or treatments deemed necessary for the subjects’ ongoing medical care. Details of 
medications, treatments and procedures will be collected at the Screening/Baseline Visit and 
updated at every study visit (including the ET Visit, if applicable). Concomitant medications 
(including prednisone/prednisolone), treatments and procedures taken/undergone during the 
study are to be recorded in the subject’s medical records and eCRF; an exception to this is 
any medication used in the course of conducting a study assessment (e.g., topical anesthesia, 
dilating eye drops).
To minimise inflammation resulting from surgery and potential or unexpected immune 
responses to vector/transgene, all subjects will be treated with a course of corticosteroid 
therapy. 

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In Part I, all subjects will be prescribed a 21-day course of oral prednisone/prednisolone 
following closely the 17-day protocol established in the voretigene neparvovec-rzyl AAV 
gene therapy clinical trial for treatment of patients with confirmed biallelic RPE65 mutation-
associated retinal dystrophy (Maguire, Simonelli et al. 2008), allowing an extra 4 days for 
tapering the dose at the end of the course, i.e., 1 mg/kg/day prednisone/prednisolone for a 
total of 10 days (beginning 2 days before the vector injection, on the day of injection, and 
then for 7 days); followed by 0.5 mg/kg/day for 7 days; 0.25 mg/kg/day for 2 days; and 
0.125 mg/kg/day for 2 days (21 days in total).
In Part II, all subjects will be prescribed a course of oral corticosteroids. In addition, at the 
time of surgery, subjects (adult and pediatric) may be treated with up to 1 mL of 
triamcinolone, 40 mg/mL solution, which must be administered via a deep sub-Tenon 
approach. 
For adults, 60 mg of oral prednisone/prednisolone will be prescribed for the initial 21 days 
(starting 3 days prior to surgery), followed by a weekly taper as follows, for a total of 
9 weeks of treatment:
Day -3 through day 17 (21 days): 60 mg by mouth once daily
Day 18 through day 24 (7 days): 50 mg by mouth once daily
Day 25 through day 31 (7 days): 40 mg by mouth once daily
Day 32 through day 38 (7 days): 30 mg by mouth once daily
Day 39 through day 45 (7 days): 20 mg by mouth once daily
Day 46 through day 52 (7 days): 10 mg by mouth once daily
Day 53 through day 59 (7 days): 5 mg by mouth once daily. 
If at the Month-2 visit (Visit 5.9), inflammation is observed, corticosteroid therapy should be 
re-initiated, via oral and/or intraocular route, based on the clinical condition of the subject, 
and the judgement of the investigator.
For pediatric subjects, oral prednisolone/prednisone will also be started 3 days prior to 
surgery. The starting dose will be based on kilogram weight of the subject, up to a maximum 
of 60 mg starting dose (rounded to the nearest 1 mg). Subsequent doses will have multipliers 
to provide the appropriate taper over an additional 6 weeks, for a total of 9 weeks of 
treatment. See tapering regimen for pediatric subjects below:
Day -3 through day 17 (21 days): Starting Dose (SD) 1 mg/kg by mouth/ once daily 
(maximum dose of 60 mg once daily)
Day 18 through day 24 (7 days): SD X 0.83 mg by mouth once daily
Day 25 through day 31 (7 days): SD X 0.67 mg by mouth once daily
Day 32 through day 38 (7 days): SD X 0.5 mg by mouth once daily
Day 39 through day 45 (7 days): SD X 0.33 mg by mouth once daily
Day 46 through day 52 (7 days): SD X 0.17 mg by mouth once daily
Day 53 through day 59 (7 days): SD X 0.08 mg by mouth once daily
If at the Month-2 visit (Visit 5.9), inflammation is observed, corticosteroid therapy should be 
reinitiated, via oral and/or intraocular route, based on the clinical condition of the subject, and 
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The local pediatric team should be involved with all children undergoing gene therapy 
surgery and should be available to give advice on the steroid doses used in each patient. 
Modifications of the protocol-defined steroid treatment are allowed based on the 
recommendation of the pediatric team, with approval from the Sponsor.
For all subjects: while subjects are taking oral steroids, special note should be made to follow 
for potential side effects (e.g., increased IOP, cataracts, hypertension, elevated blood sugar, 
infections, gastritis/peptic ulcer disease, edema, electrolyte imbalance, mood changes, 
insomnia), and appropriate prophylaxis and/or therapy should be instituted as needed (e.g., 
treatment with proton pump inhibitors, valacyclovir; restriction of nonsteroidal anti-
inflammatory agents).
8.9.
Treatment Compliance
This study involves a single sub-retinal injection of up to 0.1 mL AAV8-RPGR. Measure of 
treatment compliance with AAV8-RPGR is therefore not necessary. The exact volume 
injected at the time of surgery should be recorded on the eCRF.
Compliance with the use of prednisone/prednisolone will be captured in the eCRF.

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9.
STUDY VISITS AND PROCEDURES
The schedule of study procedures is presented in Table 3, Section 16.1.
9.1.
Visit 1 (Screening/Baseline Period)
The investigator will explain the study purpose, procedures, and subject responsibilities to 
each potential study subject. The subject's willingness and ability to meet the protocol 
requirements will be determined.
Prior to any study-specific procedure, written informed consent will be obtained. The subject 
or parent / legal guardian will sign and date 1 copy of the consent form in the presence of the 
investigator or his/her designee; where applicable, an assent form will be completed by the 
subject. The original signed form(s) will be retained at the study site and an additional copy 
will remain in the subject’s medical records; a copy will also be given to the subject or parent 
/ legal guardian. 
After informed consent/assent has been obtained, the subject will be evaluated to determine 
eligibility. Screening assessments will be considered baseline measurements and will consist 
of the following:

Demography

Medical history, including ocular history

Blood pressure and pulse

Collection of safety blood samples (hematology and clinical chemistry)

RPGR gene mutation screen (only if not conducted previously) 

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and lens 
LOCS III cataract grading

LLVA1

ETDRS BCVA1,2

SD-OCT

Fundus autofluorescence

MAIA microperimetry1,3

Fundus photography

Octopus 900 visual fields3,4

Contrast sensitivity test1


Viral shedding

Immunogenicity sampling

AE and SAE monitoring

Review of medication, treatments, and procedures 

1,6,7

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
Randomisation6
1. In Part II, it is preferable that the same masked assessor who performs these assessments 
(LLVA, BCVA, microperimetry, contrast sensitivity and 
) during the masked period from 
Month 3 through Month 12 also perform these assessments at screening.
2. For Part I subjects, BCVA is performed in triplicate at baseline. For Part II subjects, if the 
BCVA value at Visit 1 (Screening/Baseline) is ≥ ± 10 letter gain or loss in the study eye compared 
to the previous XOLARIS study visit (if applicable), then BCVA must be repeated an additional 2 
times, resulting in a total of 3 BCVA measures at Visit 1. 
For Part II subjects, if the BCVA value at Visit 1 (Screening/Baseline) is < ± 10 letter difference in 
the study eye compared to the previous XOLARIS study visit, then BCVA will be collected once 
and will not be repeated.
If subject was not previously in XOLARIS study, BCVA assessments at baseline must be 
performed in triplicate.
For all subjects who require triplicate BCVA testing, to facilitate the additional BCVA measures, 
this visit should be conducted over 2 days, with BCVA measured twice on Day 1 and once on Day 
2 (prior to pupil dilation). All 3 BCVA values must be recorded in the eCRF. The highest score 
will be used to define subject eligibility.
3. Assessments at screening collected in triplicate. To facilitate triplicate testing, the visit should 
be conducted over 2 days. Visual field and microperimetry outputs will be sent to a CRC for 
review. Data will be generated and collated within the CRC and exported to the Sponsor or 
designee. For microperimetry, the last assessment performed during screening will be used for 
assessing eligibility and will be defined as the baseline assessment.
4. Octopus 900 perimeter is specified for visual field assessments only in Part II. 
 
6. Part II only. 
 
 
Subjects who meet all the inclusion criteria and none of the exclusion criteria will have a 
study eye assigned and be enrolled into the study. In Part II, subjects will be informed of the 
randomisation outcome (i.e., AAV8-RPGR treatment or the Control group) and instructed to 
not reveal their treatment group assignment to the masked assessors during the study. 
Subjects randomised to the AAV8-RPGR treatment groups (along with the Investigators and 
sponsor) will remain masked to the assigned dose.
See Section 8.5 for details on randomisation and assignment of subject numbers.
The next study visit (Visit 2) is to be scheduled within 12 weeks of the Screening/Baseline 
Visit. Subjects will be given a course of oral prednisone/prednisolone and instructed to start 
taking the drug 2 days (Part I) or 3 days (Part II) before their next study visit (Visit 2). Where 
applicable, subjects will also be instructed to use barrier contraception or abstain from sexual 
intercourse for a period of 3 months from the time they are treated.
9.2.
Visit 2 (Day 0, Surgery/Injection Day Visit)
At Visit 2, all subjects in the AAV8-RPGR groups will visit the surgical site, and the 
following assessments will be performed prior to surgery:

Full ophthalmic examination, including indirect ophthalmoscopy, slit lamp 
examination with IOP assessment, anterior chamber, and vitreous inflammation 
grading, and LOCS III cataract grading

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
Blood pressure and pulse

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

Corticosteroid compliance review1
1.  Corticosteroid review is applicable only for treated subjects.
It may be necessary for subjects to undergo a pre-surgical workup according to local hospital 
procedures (e.g., blood draw for anesthetist) which are outside of the protocol-defined 
assessments. Any assessments performed outside of the protocol will not be collected as part 
of the study analyses.
Subjects will then undergo vitrectomy and receive a sub-retinal injection of AAV8-RPGR 
(see Section 8.4 for details). 
Subjects may be treated at the time of surgery with up to 1 mL of triamcinolone (40 mg/mL), 
administered via a deep sub-Tenon approach.
Subjects will be carefully monitored for the occurrence of AEs during the procedure. Subjects 
may stay overnight or return to the site 1 day and then 7 days after surgery for post-operative 
follow-up (Visits 3 [Day 1] and 4 [Day 7], respectively).
Subjects in the Control group will receive a study visit Telephone Call at the agreed upon 
date and time. Sites will conduct the following assessments during the telephone call:

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures
9.3.
Visit 3 (Day 1 Post-Operative Visit)
At Visit 3, the first post-operative visit, the following assessments will be performed:

Blood pressure and pulse

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

ETDRS BCVA

SD-OCT

Viral shedding

Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

Corticosteroid compliance review1
1.  Corticosteroid review is applicable only for treated subjects.
Where applicable, subjects will be reminded of the requirement to use barrier contraception 
or abstain from sexual intercourse for a period of 3 months from the time of treatment.
Subjects in the Control group will receive a study visit Telephone Call at the agreed upon 
date and time. Sites will conduct the following assessments during the telephone call:

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
AE/SAE monitoring

Review of concomitant medication, treatments, and procedures.
9.4.
Visit 4 (Day 7 Post-Operative Visit ± 3 Days)
At Visit 4, the second post-operative visit, the following assessments will be performed:

Blood pressure and pulse

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

ETDRS BCVA

SD-OCT

Viral shedding

Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

Corticosteroid compliance review1
1.  Corticosteroid review is applicable only for treated subjects.
Where applicable, subjects will be reminded of the requirement to use barrier contraception 
or abstain from sexual intercourse for a period of 3 months from the time of treatment. 
Subjects in the Control group will receive a study visit Telephone Call at the agreed upon 
date and time (± 3 days of Day 7). Sites will conduct the following assessments during the 
telephone call:

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures.
9.5.
Visit 5 (Month 1 ± 7 Days)
At Visit 5, the following assessments will be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA

ETDRS BCVA

SD-OCT

Fundus autofluorescence

MAIA microperimetry

Viral shedding

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
Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

Corticosteroid compliance review1
1.  Corticosteroid review is applicable only for treated subjects.
Where applicable, subjects will be reminded of the requirement to use barrier contraception 
or abstain from sexual intercourse for a period of 3 months from the time of treatment.
9.6.
Visit 5.9 (Month 2 ± 7 Days)
At Visit 5.9, the following assessments will be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

ETDRS BCVA

SD-OCT

Fundus autofluorescence

MAIA microperimetry

Viral shedding

Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

Corticosteroid compliance review1
1.  Corticosteroid review is applicable only for treated subjects.
Where applicable, subjects will be reminded of the requirement to use barrier contraception 
or abstain from sexual intercourse for a period of 3 months from the time of treatment.
9.7.
Visit 6 (Month 3 ± 7 Days)
At Visit 6 the following assessments will be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA1

ETDRS BCVA1

SD-OCT

Fundus autofluorescence

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
MAIA microperimetry1

Octopus 900 visual fields2

Contrast sensitivity test

Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 

1,3
1. In Part II, at Month 3, LLVA, BCVA, microperimetry and the 
 will be conducted by 
qualified masked assessors. 
2. Octopus 900 perimeter is specified for visual field assessments only in Part II. 
 
9.8.
Visit 7 (Month 6 ± 14 Days)
At Visit 7, the following assessments will be performed:

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA1

ETDRS BCVA1

SD-OCT

Fundus autofluorescence

MAIA microperimetry1

Octopus 900 visual fields2

Contrast sensitivity test1

3

Immunogenicity sampling

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 
1. In Part II, at Month 6, LLVA, BCVA, microperimetry and the 
 will be conducted by 
qualified masked assessors.
2. Octopus 900 perimeter is specified for visual field assessments only in Part II. 
 

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9.9.
Visit 8 (Month 9 ± 14 Days)
At Visit 8, the following assessments will be performed:

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA1

ETDRS BCVA1

SD-OCT

MAIA microperimetry1

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 
1. In Part II, at Month 9, 
, BCVA, and microperimetry will be conducted by qualified 
masked assessors.
9.10.
Visit 9 (Month 12 ± 14 Days)
At Visit 9, the following assessments will be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA1

ETDRS BCVA1,2

SD-OCT

Fundus autofluorescence

MAIA microperimetry1

Octopus 900 visual fields3

Fundus photography

Contrast sensitivity test1

4

Immunogenicity sampling

AE/SAE monitoring

1,5

Review of concomitant medication, treatments, and procedures 
1. In Part II, at Month 12, LLVA, BCVA, microperimetry, contrast sensitivity, and the 
 
will be conducted by qualified masked assessors.
2. Part I subjects perform BCVA assessments in triplicate at Month 12. To facilitate the additional 
BCVA measures, this visit should be conducted over 2 days, with BCVA measured twice on Day 1 
and once on Day 2 (prior to pupil dilation). All 3 BCVA values must be recorded in the eCRF. 

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3. Octopus 900 perimeter is specified for visual field assessments only in Part II. 
 
 
Subjects who develop cataracts should undergo cataract surgery if deemed clinically 
necessary; if surgery is performed, it should be carried out at least 4 weeks before Visit 9 
(Month 12) or Visit 11 (Month 24) for Part II and Part I subjects, respectively. 
Although the visit will still be considered out-of-window, if Part II subjects are unable to 
attend their final 12-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 12-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited to 
scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
9.11.
Visit 10 (Month 18 ± 14 Days) (Part I Subjects Only)
At Visits 10, the following ocular assessments will be performed:

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA

ETDRS BCVA

SD-OCT

Fundus autofluorescence

MAIA microperimetry

Fundus photography

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 
9.12.
Visit 11 (Month 24 ± 14 Days) (Part I Subjects Only)
At Visits 11, the following ocular assessments will be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA

ETDRS BCVA1

SD-OCT

Fundus autofluorescence

MAIA microperimetry

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
Fundus photography

Visual Fields 

Contrast sensitivity test

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 
1. Part I subjects perform BCVA assessments in triplicate at Month 24. To facilitate the additional 
BCVA measures, this visit should be conducted over 2 days, with BCVA measured twice on Day 1 
and once on Day 2 (prior to pupil dilation). All 3 BCVA values must be recorded in the eCRF. 
Although the visit will still be considered out-of-window, if Part I subjects are unable to 
attend their final 24-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 24-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited to 
scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
9.13.
Early Termination (ET) Visit
If a subject discontinues the study at any time, the site should use every reasonable effort to 
ensure that an ET Visit is conducted. The following assessments should be performed:

Collection of safety blood samples (hematology and clinical chemistry)

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

LLVA1

ETDRS BCVA1

SD-OCT

Fundus autofluorescence

MAIA microperimetry1

Octopus 900 visual fields2

Fundus photography

Contrast sensitivity test1


Immunogenicity sampling

AE/SAE monitoring

1,4

Review of concomitant medication, treatments, and procedures
1. In Part II, at the ET Visit, LLVA, BCVA, microperimetry, contrast sensitivity, and the 
 
will be conducted by qualified masked assessors.
2. Octopus 900 perimetry is specified for visual field assessments only in Part II. 
3. In Part II and only at sites with available technology. 

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9.14.
Unscheduled Visits
If clinically indicated, subjects may need to return to the site for an unscheduled visit. At a 
minimum, the following assessments will be performed.

Full ophthalmic examination, including indirect ophthalmoscopy, a slit-lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and 
LOCS III cataract grading

ETDRS BCVA1

SD-OCT

Fundus autofluorescence

MAIA microperimetry, if clinically feasible1

AE/SAE monitoring

Review of concomitant medication, treatments, and procedures 
1.
For unscheduled visits that occur during Part II, BCVA and microperimetry will be conducted 
by qualified masked assessors from Month 3 through Month 12. 

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10.
ASSESSMENT OF EFFICACY
All efforts should be made to conduct the efficacy assessments; if a subject is not able to 
perform an assessment due to poor VA, it will be documented accordingly in the eCRF and 
will not be recorded as a protocol deviation.
10.1.
Best-Corrected Visual Acuity
To evaluate changes in VA over the study period, BCVA will be assessed for both eyes using 
the ETDRS VA chart at the times indicated in Table 3, Section 16.1.
The 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 subject. 
In Part I, at the Screening/Baseline Visit, eyes will be eligible for the study if they:

Have better than or equal to light perception (Cohort 1 only), or

Have a BCVA of 34-73 ETDRS letters (equivalent to worse than or equal to 6/12 
or 20/40 Snellen acuity, but better than or equal to 6/60 or 20/200 Snellen acuity) 
(Cohorts 2-3)

Have a BCVA better than or equal to 34 ETDRS letters (equivalent to better than 
or equal to 6/60 or 20/200 Snellen acuity) (Cohort 4 [5 and 6, if applicable] and 
MTD cohort)
In Part II, at the Screening/Baseline Visit, eyes will be eligible for the study if they have a 
BCVA better than or equal to 34 ETDRS letters.
For BCVA, assessors will be appropriately qualified for conducting the assessment. 
For Part I subjects, BCVA will be performed in triplicate over a 2-day period at Visits 1, 9 
and 11 (or ET Visit) for all subjects. It is recommended that BCVA will be conducted twice 
on the first day and once on the second day. All values will be entered in the eCRF.
For Part II subjects, if the BCVA value at Visit 1 (Screening/Baseline) is ≥ ± 10 letter gain or 
loss in the study eye compared to the previous XOLARIS study visit (if applicable), then 
BCVA must be repeated an additional 2 times, resulting in a total of 3 BCVA measures at 
Visit 1. To facilitate the additional BCVA measures this visit should be conducted over 2 
days, with BCVA measured twice on Day 1 and once on Day 2 (prior to pupil dilation). All 
3 BCVA values must be recorded in the eCRF. The highest score will be used to determine 
subject eligibility.
If the BCVA value at Visit 1 (Screening/Baseline) is < ± 10 letter difference in the study eye 
compared to the previous XOLARIS study visit, then BCVA will be collected once and will 
not be repeated.
If subject was not previously in XOLARIS study, BCVA assessments at baseline must be 
performed in triplicate.
In Part II, it is preferable that the same masked assessor who performs the BCVA 
assessments during the masked period from Month 3 through Month 12 also perform these 
assessments at screening. 

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10.2.
Spectral Domain Optical Coherence Tomography (SD-OCT)
SD-OCT will be performed for both eyes at the times indicated in Table 3, Section 16.1. SD-
OCT measurements will be taken by certified technicians at the site after dilation of the 
subject’s pupil. All OCT scans will be submitted by the sites to a Central Reading Centre 
(CRC) where the scans will be evaluated; the CRC will enter the data into the Electronic Data 
Capture (EDC) system. SD-OCT will be used to quantify integrity of the EZ and reduction in 
the signal from the outer nuclear layer and choroid. In addition, foveal changes will be 
assessed.
For complete technical specifications for SD-OCT, refer to the Study Operations Manual 
(which will include procedures from the CRC regarding how measurements are to be taken).
10.3.
Fundus Autofluorescence
To assess changes in the area of viable retinal tissue, fundus autofluorescence will be 
performed for both eyes at the times indicated in Table 3, Section 16.1. All fundus 
autofluorescence images will be performed by certified technicians at the site after dilation of 
the subject’s pupil and sent to a CRC for review; the CRC will enter the data into the EDC 
system. For complete technical specifications for fundus autofluorescence, refer to the Study 
Operations Manual (which will include procedures from the CRC regarding how 
measurements are to be taken).
10.4.
MAIA Microperimetry
MAIA Microperimetry will be conducted for both eyes at the times indicated in Table 3, 
Section 16.1. MAIA microperimetry will be conducted by certified technicians to assess 
changes in retinal sensitivity within the macula. Microperimetry must be performed on both 
eyes in triplicate and should be conducted over a 2-day period at Visit 1 for all subjects. The 
final assessment should be used to determine subject eligibility. If at subsequent visits there 
are obvious technical challenges or the subject is not performing the assessment as expected 
from previous visits (e.g. distracted, large number of false positive responses, not maintaining 
fixation, etc), then the assessment may be repeated and the second assessment should be used 
for that study visit.
All microperimetry images will be sent by the sites to a CRC for review. For complete 
technical specifications for microperimetry, refer to the Study Operations Manual (which will 
include procedures from the CRC regarding how measurements are to be taken).
In Part II, it is preferable that the same masked assessor who performs the microperimetry 
assessments during the masked period from Month 3 through Month 12 also perform these 
assessments at screening. 
10.5.
Visual Field Testing (Perimetry)
Visual fields will be assessed in both eyes at the times indicated in Table 3, Section 16.1 only 
at sites where the required perimetry equipment, as specified in the Study Operations Manual, 
is available. Visual fields will be assessed in triplicate over a 2-day period at Visit 1 for all 
subjects. Visual field outputs will be sent to a CRC for review. Data will be generated and 
collated within the CRC and exported to the Sponsor or designee for inclusion in the study 
database. In Part II, visual fields should be assessed using the Octopus 900 perimeter. 

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10.6.
Contrast Sensitivity
Contrast sensitivity will be measured for both eyes at the times indicated in Table 3, Section 
16.1. For contrast sensitivity, assessors will be appropriately qualified for conducting the 
assessment.
In Part II, it is preferable that the same masked assessor who performs the contrast sensitivity 
assessments during the masked period from Month 3 through Month 12 also perform these 
assessments at screening. 
10.7.
Low Luminance Visual Acuity
Low luminance visual acuity will be measured for both eyes at the times indicated in Table 3, 
Section 16.1. The test should be performed before BCVA testing and pupil dilation. LLVA is 
measured by placing a 2.0-log-unit neutral density filter over the front of each eye and having 
the subject read the normally illuminated ETDRS chart. 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. LLVA is to be reported as number of letters read correctly by the subject.
In Part II, it is preferable that the same masked assessor who performs the LLVA assessments 
during the masked period from Month 3 through Month 12 also perform these assessments at 
screening. 
 
 See Table 3, Section 16.1.
 
 
 
 
 
 
 

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11.
ASSESSMENT OF SAFETY
All efforts should be made to conduct the safety assessments; if a subject is not able to 
perform an assessment due to poor VA, it will be documented accordingly in the eCRF and 
will not be recorded as a protocol deviation.
11.1.
Dose Limiting Toxicity
See Section 6.1.1 for definitions of DLTs; See Section 11.2.4 for instruction on reporting 
DLTs.
11.2.
Evaluation, Recording, and Reporting Adverse Events
11.2.1.
Definitions
11.2.1.1.
Adverse Event
An AE is any untoward medical occurrence in a clinical investigation subject, which does not 
necessarily have a causal relationship with the study drug/surgical procedure. An AE can 
therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), 
symptom, or disease temporally associated with the use of the study drug/surgical procedure, 
whether or not related to the investigational product or with the surgical procedure described 
in this protocol.
AEs are to also include any pre-existing condition (other than XLRP) or illness that worsens 
during the study (i.e., increases in frequency or intensity).
11.2.1.2.
Serious Adverse Event
An SAE is defined as any untoward medical occurrence that:

Results in death

Is life-threatening

Requires inpatient hospitalization or prolongation of existing hospitalization

Results in persistent or significant disability/incapacity

Is a congenital anomaly/birth defect

Results in vision loss or is vision threatening

Is another important medical event(s).
The term ‘life-threatening’ in the definition of ‘serious’ refers to an event in which the 
subject is at risk of death at the time of the event. It does not refer to an event that 
hypothetically might cause death if it were more severe.
Hospitalisation that was pre-scheduled or for an elective procedure or routinely scheduled 
treatment for a pre-existing condition, which has not worsened, does not constitute an SAE.
Other events that may not result in death, are not life threatening or do not require 
hospitalization, may be considered an SAE when, based upon appropriate medical judgment, 
the event may jeopardize the subject and may require medical or surgical intervention to 
prevent 1 of the outcomes listed above.

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Vision Loss to Be Reported as a Serious Adverse Event
Vision Loss NOT TO BE Reported as an SAE:

Surgery-related BCVA decrease of ≥15 letters on ETDRS chart occurring 
within1 day of surgery but recovering / resolving at post-operative Day 7. 
Vision Loss or Vision-Threatening Event TO BE Reported as an SAE:

Surgery-related BCVA decrease of ≥15 letters on ETDRS chart that occurs within 
1 day of surgery and that has not recovered* by the 1-Month Visit.

A decrease in BCVA of ≥15 letters on ETDRS chart that occurs within 1 day of 
surgery, however, in the investigator’s opinion:
o
Has an evolution not consistent with the expected post-operative course; 
o
May be attributable to a complication that occurred during surgery, or another 
untoward event, or the study drug; 
o
Actually or potentially requires any surgical or medical intervention to prevent 
permanent loss of vision.

Non-surgery-related, sustained (>48 hours duration) decrease from baseline in 
BCVA of ≥15 letters on ETDRS chart.
*Recovery / Resolution of BCVA loss is defined as a return to within 10 letters of the 
baseline BCVA on the ETDRS chart.
11.2.2.
Recording of Adverse Events
AEs/SAEs will be collected from the time the subject or parent / legal guardian (where 
applicable) provides written informed consent through Visit 11 (or ET Visit or Unscheduled 
Visits, if applicable).
AEs/SAEs that the investigator becomes aware of, and which are deemed to have a 
relationship to the study drug, should continue to be reported to NightstaRx following the 
completion of the study for a period of up to 5 years following surgery, until/unless the 
subject is enrolled in another NightstaRx study. 
Subjects will be questioned on the occurrence of an AE at every visit including any 
unscheduled visit, by using non-leading questioning such as ‘How have you been since the 
last visit?’
All AEs occurring during the study observed by the investigator or reported by the subject, 
whether attributed to study drug or the surgical procedure, will be recorded in the subject’s 
medical records and in the eCRF. Any clinically significant changes in laboratory results or 
vital sign measurements (as determined by the investigator) are to be recorded as an AE.
The following information will be recorded in the eCRF for each AE: description, date of 
onset and end date, outcome, severity, assessment of relatedness to study drug/study 
procedure, the action taken and confirmation of whether the event is considered serious (see 
Section 11.2.1.2 for the definition of seriousness). Follow-up information should be provided 
as necessary (see Section 11.2.3 for specifics on follow-up procedures).
AE severity and relationship to the study drug or the surgical procedure will be assessed at 
the site by the investigator or a medically qualified designee.

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AE Severity
The severity of events will be assessed on the following scale:
1.  = mild (awareness of sign or symptom, but easily tolerated)
2.  = moderate (discomfort sufficient to cause interference with normal activities)
3.  = severe (incapacitating, with inability to perform normal activities).
AE Relationship
When assigning relatedness of the AE, consideration will be given to whether there is a 
plausible relationship to either the study drug or the surgical procedure. The following are 
definitions of relatedness that will be used in this study:
Unrelated: 
is not reasonably related in time to the administration of the 
study drug/surgical procedure, or exposure of the study 
drug/surgical procedure has not yet occurred, or biologic 
plausibility does not exist
Related:
A reasonable possibility exists that the study drug / study 
procedure caused the AE. A suspected AE can be further 
defined by:
Possibly related: clinically or biologically reasonable relative 
to the administration of the study drug/surgical procedure, but 
the event could have been due to another equally likely cause
Probably related: is clinically/biologically reasonable relative 
to the administration of the study drug/surgical procedure, and 
the event is more likely explained by exposure 
to/administration of the study drug/surgical procedure than by 
other factors and causes
Definitely related: There is a causal relationship of the onset of 
the event, relative to administration of the study drug/surgical 
procedure and there is no other cause to explain the event.
When a relationship is determined to exist, the investigator or medical designee will further 
define if that relationship is to the study drug, the surgical procedure, both, or unknown.
11.2.3.
Follow-up of Adverse Events
AEs will be followed until the subject has recovered or the subject’s participation in the study 
is complete.
Subjects who are withdrawn from the study as a result of a drug-related AE will be followed 
up until the event has resolved, subsided, stabilized or the subject or parent / legal guardian 
(where applicable) withdraws consent or is lost to follow-up.
All SAEs, regardless of attribution to study drug or the surgical procedure, should be 
followed-up until the event has resolved, subsided, stabilized or the subject or parent / legal 
guardian (where applicable) withdraws consent or is lost to follow-up. The Sponsor (or 
designee) will follow up on SAE reports to completion. Investigators are expected to provide 
the requested additional information for a complete assessment and documentation of the 
SAE reports in a timely manner.

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11.2.4.
Reporting of Serious Adverse Events and Dose-Limiting Toxicities
The investigator shall immediately (within 24 hours of learning of the event) report any SAE 
(and/or DLT) to the Sponsor (or its designee) by completing and emailing the DLT/SAE 
form. For reporting purposes, the date of SAE form submission by the investigator to the 
Sponsor will be designated as Day 0. The initial report shall be promptly followed up with a 
more detailed report providing specifics about the subject and the event. Copies of hospital 
reports, autopsy reports and other documents should be provided (if applicable).
The sponsor may unmask any SAE reports that are serious, unexpected, and related to the 
study drug, as required, in accordance with safety reporting guidance and regulations.
The sponsor will report Suspected Unexpected Serious Adverse Reactions (SUSARs) to 
investigative sites, Institutional Review Boards/Independent Ethics Committees (IRBs/IECs) 
and regulatory authorities in compliance with current legislation. All cases that are fatal or 
life-threatening will be reported immediately after the sponsor receives the initial report from 
the Investigator. All non-fatal or non-life-threatening cases will be reported within a 
maximum of fifteen days after the initial Investigators report. The sponsor will also provide 
periodic safety reports to IRBs/IECs and regulatory authorities as applicable. Follow-up SAE 
reports will be submitted within 15 days of receiving the information.
A sample DLT/SAE form is provided in the Study Operations Manual, along with the SAE 
reporting contact information.
11.2.5.
Procedures for Unmasking 
The Investigator has the ability to unmask an individual subject’s treatment assignment to 
provide emergency treatment. Unmasking is appropriate when knowledge of the subject’s 
dose would affect the medical management of the subject. 
If the Investigator determines the unmasking is required, then s/he unmasks the subject 
through the Electronic Data Capture (EDC) system, files the resulting confirmation in a 
restricted file until the end of the study, and notifies the Medical Monitor within 24 hours that 
the subject’s treatment assignment has been unmasked. The Investigator will not 
communicate the treatment assignment to the Medical Monitor or to any sponsor or study 
team staff; nor should the treatment assignment be communicated to site staff other than 
those personnel who require that knowledge in order to treat the subject.
The Investigator will ensure that the rationale, date, and time of unmasking is noted in the 
subject’s source documentation, but not the treatment assignment. The medical emergency 
that necessitated unmasking must also be recorded in the source documentation and the case 
report form per standard study procedures.
11.2.6.
Data Monitoring Committee
For Part I, an independent DMC will be used in this study to safeguard the safety and 
interests of study subjects and assess the safety and benefit/risk of the gene therapy 
intervention during the trial. At regular intervals during the study, the DMC will review the 
progress and accrued study data and provide advice to the Sponsor on the safety aspects of 
the study, including recommendations for dose escalation (see Section 6.3 ). The DMC will 
inform the Sponsor if there is a consensus that the ongoing data show that the gene therapy, 
its method of administration, and/or the study design are no longer in the best interests of 
study subjects.

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In Part II, DMC will be held to review safety and assess benefit/risk during the course of the 
study.
If one IA is performed, the study will continue as planned in a masked fashion. 
11.3.
Pregnancy
Any pregnancy that occurs during the clinical study in a female partner of a study subject 
should be recorded on a Pregnancy Notification Form. Consent from the pregnant partner is 
required prior to the collection of personal data. However, the investigator shall immediately 
(within 24 hours of learning of the event) report the pregnancy, with at least preliminary data, 
to the Sponsor (or its designee) by completing and emailing a Pregnancy Notification Form. 
In addition, if possible, outcome of the pregnancy fathered by the subject should be recorded, 
including any congenital abnormality or birth defects.
11.4.
Full Ophthalmic Examination
A full ophthalmic examination will be conducted for both eyes at the times indicated in Table 
3, Section 16.1. The ophthalmic examination will include indirect ophthalmoscopy, slit lamp 
examination, IOP, anterior chamber and vitreous inflammation grading and LOCS III cataract 
grading. The same slit lamp machine and lighting conditions should be used across study 
visits for any given subject.
Subjects who develop cataracts may undergo cataract surgery if deemed clinically necessary; 
if surgery is performed, it should be carried out at least 4 weeks before the Visit 9 (Month 12) 
or Visit 11 (Month 24).
11.5.
Fundus Photography
To aid in the objective clinical assessment of progressive retinal changes in the periphery of 
the retina, fundus photography will be performed for both eyes at the times indicated in Table 
3, Section 16.1. Fundus photography will be performed by certified technicians following 
pupil dilation. All fundus photographs will be sent by the sites to the CRC for review; the 
CRC will enter the data into the EDC system. For complete technical specifications for 
fundus photography, refer to the Study Operations Manual (which will include procedures 
from the CRC regarding how measurements are to be taken).
11.6.
Vital Signs
Vital signs (pulse and systolic and diastolic blood pressure) will be taken at the times 
indicated in Table 3, Section 16.1. Vital signs should be taken after the subject is seated for at 
least 5 minutes.
11.7.
Laboratory Assessments
11.7.1.
Laboratory Safety Parameters
Blood samples will be collected at the times indicated in Table 3, Section 16.1 for 
measurement of hematology and clinical chemistry parameters. Samples will be sent to a 
central laboratory for analysis. Refer to the Study Operations Manual for details on the 
shipping and handling of samples.
The hematology and clinical chemistry parameters to be evaluated are outlined in Table 2.

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Table 2
Laboratory Safety Parameters
Hematology
Clinical Chemistry
Hematocrit
Albumin
Hemoglobin
Alkaline phosphatase
Platelet count
Aspartate transaminase
Red blood cell count
Alanine transaminase
Bilirubin (total)
Blood urea nitrogen
Calcium
Chloride
Creatinine
C-reactive protein
Gamma glutamyl transferase 
Globulin
Glucose (non-fasting)
Lactate dehydrogenase
Magnesium
Phosphate
Potassium
Protein (total)
White blood cell count with differential
Sodium
11.7.2.
Viral Shedding
Blood, tears (both eyes), saliva and urine samples will be collected at the times indicated in 
Table 3, Section 16.1 and tested by polymerase chain reaction amplification of vector 
genomes to assay for evidence of vector shedding and dispersion. Samples will be sent to a 
central laboratory for analysis. Refer to the Study Operations Manual for details on the 
shipping and handling of samples.
11.7.3.
Immunogenicity Testing
For the evaluation of immunogenicity, blood will be collected at the times indicated in Table 
3, Section 16.1. 
Immunoassays are planned to assess antibody and cell-based responses against 
AAV8-RPGR. Enzyme-linked immunospot (ELISPOT) assays will be used for T-cell 
mediated immune responses to transgene, and antibody responses will be assayed using 
enzyme-linked immunosorbent assay-based methods and cell-based methods.
All immunogenicity samples will be sent to central laboratories for analyses. Refer to the 
Study Operations Manual for details on the shipping and handling of samples.
Residual samples may be stored for up to 15 years or per local regulations. 

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12.
STATISTICAL CONSIDERATIONS
For full details of the statistical analyses, please refer to the XIRIUS Statistical Analysis Plan 
(SAP). 
12.1.
Sample Size
Due to the nature of the study design of Part I, no formal sample size computation was 
performed. 
In Part II, the primary endpoint is the proportion of study eyes with ≥7 dB improvement from 
baseline at ≥5 of the 16 central loci of the 10-2 grid assessed by MAIA microperimetry at 
12 months. A sample size of 10 subjects from a treatment group (either high dose or low 
dose), and 9 subjects from the untreated control group, will provide approximately 
87% power, assuming the treatment group has a 50% response rate and the untreated group 
has a 5% response rate. The power calculation is based on Fisher Exact-Boschloo test with a 
Berger-Boos correction of beta = 0.001, at a right-sided significance level of 0.10. 
12.2.
Procedure for Accounting for Missing Data
All reasonable efforts will be made to obtain complete data for both eyes on all subjects. 
However, missing observations may occur. Management of dropouts and missing 
observations will depend on their nature and frequency.
Part I is an open-label study. For efficacy endpoints, observations collected within 6 months 
of the last visit window will be included in the primary analysis. Efficacy endpoints will be 
summarized on observed data and no imputation will be performed. Safety endpoints will 
also be analysed on observed data and no imputation will be performed.
Part II is a randomized and double-masked study. For efficacy endpoints, observations 
collected within 6 months of the last visit window will be included in the primary analysis. 
Additional imputation approaches will be specified in the SAP. Safety endpoints will be 
analysed on observed data and no imputation will be performed.
12.3.
Analysis Sets
12.3.1.
Safety Analysis Set
For Part I, the Safety Analysis Set will consist of all subjects who receive study treatment 
(vitrectomy/AAV8-RPGR). The Safety Analysis Set will be used for all analyses in Part I. 
For Part II, the Safety Analysis Set will consist of all subjects who are randomised under both 
the 2- and the 3-arm randomisation schedules and receive study treatment when randomized 
to active treatment, or attend Visit 2 (telephone call) when randomized to control (no 
treatment). Safety summaries of Part II will use the Safety Analysis Set and subjects will be 
analysed based on the actual treatment received. 
12.3.2.
Intent-to-Treat (ITT) Analysis Set
The intent-to-treat (ITT) Analysis Set will consist of all Part II subjects who are randomised, 
under the 3-arm randomisation schedule. The efficacy summaries of Part II will be generated 
using the ITT Analysis Set. Subjects will be analysed based on the treatment to which they 
were randomised.

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12.4.
Descriptive Statistics
Summary statistics will be presented for both eyes (Study Eyes versus Fellow Eyes). No 
formal statistical comparison will be performed in Part I. Formal statistical testing will be 
conducted for the primary endpoint in Part II. Continuous variables and their change from 
baseline will be summarized using descriptive statistics (number of subjects [n], mean, 
standard deviation, median, minimum, maximum, first and third quartiles, fifth and ninety-
fifth percentiles). The CIs of the mean and the mean change from baseline at each visit may 
be provided where applicable. For categorical variables, the number and proportion of 
subjects pertaining to each category will be presented over time. The CIs of the proportion 
may be provided where applicable.
12.5.
Demographics and Baseline Characteristics
Demographics and baseline ocular characteristics will be summarised by Safety Analysis Set 
in both Part I and Part II 
12.6.
Efficacy Analyses
Efficacy assessments are ocular in nature and therefore will be tabulated by eye (Study Eye 
and Fellow Eye). In Part I, efficacy endpoints will be summarised on observed data using 
descriptive statistics only (described in Section 12.4). In Part II, efficacy endpoints will be 
summarized on observed data using descriptive statistics. Additional analyses for handling 
missing data will be provided for the primary endpoint and selected secondary endpoint.  
For each subject, data collected within 6 months of the last visit window will be included in 
the primary analysis, as described in greater detail in the SAP. 
At final analysis in Part II, the primary endpoint, which is defined as the proportion of study 
eyes with ≥7 dB improvement from baseline at ≥5 of the 16 central loci at 12 months, will be 
compared between treatment groups (high dose vs untreated; low dose vs untreated) using the 
Fisher Exact-Boschloo test with a Berger-Boos correction of beta=0.001 (Berger and Boos 
1994). The CIs for the difference in proportions between treatment groups will be presented 
by Miettinen and Nurminen (Miettinen and Nurminen 1985) method. 
For the continuous variables of mean sensitivity, BCVA, and LLVA in Part II, the primary 
analysis to handle missing data uses a mixed model repeated measures (MMRM) model. The 
mean change from baseline will be analyzed using fixed effects of treatment group, study 
visit, study-visit-treatment interaction, and baseline value. 
12.6.1.
Multiplicity Adjustment
Part I is the dose-escalation to identify the MTD based on the evaluation of benefit/risk 
without any formal statistical comparisons, and therefore no multiplicity adjustment is 
needed. 
In Part II, a single administrative IA may be included to facilitate the planning of Phase 3 
activities. As no early stopping for efficacy is allowed, no multiplicity adjustment is required 
for this administrative IA. At final analysis, the primary endpoint will be tested using 
Hochberg’s (Hochberg 1988) step-up method with familywise error rate controlled at one-
side 0.10. The study will be declared positive if either dose or both doses achieve statistical 
significance.

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12.7.
Safety Analyses
Due to the potential systemic effect of study treatment (surgery/study drug) on the 
contralateral eye, ocular assessments and AEs will be summarised by eye (Study Eye and 
Fellow Eye) while systemic assessments will be analysed at the subject level. No formal 
statistical testing will be performed for safety analyses. Safety analyses will be performed on 
the Safety Analysis Set.
12.7.1.
Adverse Events
AEs will be coded using the Medical Dictionary for Regulatory Activities. The version of the 
dictionary current at the time of the database lock will be used.
AEs will be summarised by system organ class and preferred term. Both the number of 
eyes/subjects experiencing an AE and the number of events will be summarized. The SAEs, 
severity, and relationship to study drug/procedure will be also summarized. A by-subject listing of 
SAEs and DLTs (Part I only) will be provided. 
12.7.2.
Ocular Safety Evaluations
IOP and changes from baseline in IOP, abnormal slit lamp examination findings and indirect 
ophthalmoscopy findings, and anterior chamber and vitreous inflammation grading will be 
summarised by visit and eye.
Lens opacity categories and shifts from baseline will be summarised by visit and eye.
Categories of fundus photography findings (none/mild/moderate/severe) will be summarised 
by visit and eye.
The number of subjects with a 5, 10 and 15letter decrease from baseline in BCVA will be 
tabulated by visit and by eye.
12.7.3.
Laboratory Assessments and Vital Signs
Laboratory assessments and vital signs will be summarised in a descriptive manner 
(described in Section 12.4).
12.8.
Interim Analysis 
 
In Part II, a single administrative IA may be performed. If this IA is performed, the study will 
continue as planned in a masked fashion. 

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13.
INFORMED CONSENT, ETHICAL REVIEW AND 
REGULATORY CONSIDERATIONS
13.1.
Informed Consent
Subjects with XLRP who meet all the entry criteria and might be expected to benefit from 
gene therapy will be invited to take part in the study. Subjects or parent / legal guardian 
(where applicable) must personally sign and date the latest IEC/ IRB approved version of the 
informed consent form before any study-specific procedures are performed. Where 
applicable, a subject assent form will be obtained.
Written and verbal versions of the subject information and informed consent will be 
presented to the subject or parent / legal guardian (where applicable) detailing no less than: 
the exact nature of the study; the implications and constraints of the protocol; and the known 
side effects and any risks involved in taking part. It will be clearly stated that the subject is 
free to withdraw from the study at any time for any reason without prejudice to future care, 
and with no obligation to give the reason for withdrawal.
The subject or parent /legal guardian (where applicable) will be allowed as much time as 
needed to consider the information and the opportunity to question the investigator, their 
primary care physician/general practitioner or other independent parties to decide whether 
they will participate in the study. Written informed consent will then be obtained by means of 
subject or parent / legal guardian (where applicable) dated signature and dated signature of 
the person who presented and obtained the informed consent. Where applicable, a subject 
assent form will be obtained. The person who obtained the consent/assent must be suitably 
qualified and experienced and have been authorized to do so by the investigator. A copy of 
the signed informed consent will be given to each subject or parent / legal guardian. The 
original signed form will be retained at the study site and an additional copy will remain in 
the subject’s medical records.
Each subject will have 1 eye treated. Selection of the “study eye” will be made on clinical 
grounds and will generally be the worse eye affected. This will be discussed in detail and 
agreed with each subject as part of the informed consent process.
This is an assessor-masked study. All subjects will be informed at the time of randomisation 
whether they have been randomised to the AAV8-RPGR or Control group. However, subjects 
in the AAV8-RPGR treatment groups will be masked to the assigned dose level.
In the case of a female partner pregnancy fathered by a subject, a partner pregnancy informed 
consent form must be signed and dated before collecting information regarding the outcome 
of the pregnancy (birth or spontaneous abortion), as well as any incidents of congenital 
abnormality, birth defect or other medical problems. 
13.2.
Ethical/Regulatory Review
The protocol, informed consent/assent form, subject information sheet and any proposed 
advertising material will be submitted, in accordance with local requirements, to an 
appropriate Research Ethics Committee (IEC or IRB), regulatory authorities and host 
institution(s) for written approval. If there are any changes to the approved protocol (with the 
exception of emergency modifications required for the subject’s safety), a protocol 
amendment will be issued by the Sponsor. When required by local law, the IEC/IRB and 
Competent Authority must give written approval of any amendments likely to affect the 

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safety of subjects or study conduct. Each site must maintain accurate and updated records of 
all correspondence with the IEC/IRB.
13.3.
Regulatory Considerations
The study will be conducted in full conformity with all applicable laws and regulations, 
including the International Conference on Harmonisation Guidelines for Good Clinical 
Practice (CPMP/ICH/135/95).
The study will be conducted in accordance with the relevant articles of the Declaration of 
Helsinki, where permissible.

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14.
ADMINISTRATIVE PROCEDURES
14.1.
Data Quality Control and Assurance
The study will be conducted in accordance with the current approved protocol, ICH GCP, 
relevant regulations, and standard operating procedures (SOPs).
The Sponsor and its selected vendors have systems in place for implementing and 
maintaining quality assurance and quality control systems, with written SOPs to ensure that 
all aspects of the trial will be conducted in compliance with this protocol and data will be 
generated, documented and reported in compliance with this protocol.
Data will be entered into a validated clinical study database and subject to programmed 
validation checks and manually verified for accuracy and completeness by a Sponsor’s 
representative, both remotely and during on-site monitoring visits. Any discrepancies will be 
resolved with the investigator or designee, as appropriate.
Regular monitoring will be performed by the Sponsor or its designee according to ICH GCP. 
Data will be evaluated for compliance with the protocol and accuracy in relation to source 
documents. Following written SOPs, the monitors will verify that the study is conducted, and 
data are generated, documented, and reported in compliance with the protocol, ICH GCP, and 
applicable regulatory requirements.
In addition, this study will be subject to quality assurance audits to independently verify 
compliance with the protocol.
14.2.
Data Handling and Records Management
The investigator must maintain adequate and accurate source documents, which will be the 
basis of information for the eCRFs. The source documents are to be separate and distinct 
from the eCRFs. All study data will be entered on an encrypted EDC system with individual 
pass-codes known to each investigator and appropriately delegated study team members. This 
electronic data entry system has been validated. Incomplete or inconsistent data will result in 
data queries that require resolution by the investigator or designee.
The investigator must ensure that clinical study records are retained according to national 
regulations. The investigator must immediately inform the Sponsor if any documents are to 
be destroyed, transferred to another facility, or transferred to a different owner.
In addition, files containing photos or digital outputs will be electronically transmitted to the 
reading center for centralized, standardised review. Data from these reading centers will 
either be entered into the EDC system or provided as an external data set that will be loaded 
directly into the study database.
Samples will also be provided to a central laboratory for analysis of vector shedding and 
immunogenicity. Results from these analyses will also be provided as an external data set that 
will be loaded directly into the study database.
The investigator must retain sufficient documentation that these images, outputs, and samples 
were handled and transmitted appropriately.
14.3.
Access to Source Documentation and Subject Privacy
Direct access will be granted to authorized representatives from the Sponsor (or designee), 
host institution, the IEC/IRB, and regulatory authorities to permit trial-related monitoring, 
audits and inspections.

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The trial staff will ensure that the subject’s anonymity is maintained. All documents will be 
stored securely and only accessible by trial staff and authorized personnel. Subjects will be 
identified by a subject ID number on the eCRF and any electronic database. The subject’s 
name and any other identifying detail will NOT be included in any study data electronic file. 
The study will comply with the data protection laws which require data to be anonymized as 
soon as it is practical to do so.
Subject medical information obtained in this study is confidential, and disclosure to third 
parties other than those noted below is prohibited. As required by Personal Information 
Protection and Electronics Documents Act and Personal Health Information Protection Act, 
upon the subject’s permission, medical information may be given to his or her personal 
physician or other appropriate medical personnel responsible for his or her welfare. Data 
generated by this study must be available for inspection by regulatory agencies, national and 
local health authorities, the Sponsor or their representative, and the IEC/IRB.
14.4.
End of the Study
Part I includes 24 months of follow-up for each subject enrolled and treated. Part II includes 
12 months of follow-up for each subject enrolled and treated.
The end of the study is defined as the date the last subject completes his final-visit 
assessments, or early termination [ET] assessments in the event of premature discontinuation, 
or the date of last data collection if the last subject is lost to follow-up.
14.5.
Policy for Publication and Presentation of Data
The detailed procedures for publications and data presentations are set out in the clinical trial 
agreement entered with the Sponsor (or designee) in connection with this study.

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15.
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16.
APPENDICES
16.1.
Schedule of Study Procedures
Table 3 presents a schedule of study procedures.

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Table 3
Schedule of Study Procedures
Study Visit
Screening/
Baselinea
Day 0
Day 1
Day 7
Month 
1
Month 
2
Month 
3
Month 
6
Month 
9
Month 
12b 
Year 1
Month 
18 c
Month 
24 
Year 2 
c,d
ET 
Visite
Uns. 
Visitf
Visit Window
(±3d)
(±7d)
(±7d)
(±7d)
(±14d)
(±14d)
(±14d)
(±14d)
(±14d)
Visit Number
Visit 1
Visit 2g
Visit 3 g
Visit 4 g
Visit 5
Visit 
5.9
Visit 6
Visit 7
Visit 8
Visit 9
Visit 10
Visit 11
Assessments/Procedures
(All Subjects/ Both Eyes, 
Unless Otherwise 
Specified)
Informed 
consent/assent
X
Demography
X
Medical history, incl 
ocular history
X
Blood pressure
X
X
X
X
Pulse
X
X
X
X
Safety blood samplesh
X
X
X
X
X
X
X
X
RPGR mutation screeni
X
Full ophthalmic 
examinationj
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surgical 
procedure/dosingk
X
Dispensation of oral 
steroidsl
X
ETDRS BCVAm
X
X
X
X
X
X
X
X
X
X
X
X
X
SD-OCT 
X
X
X
X
X
X
X
X
X
X
X
X
X
LLVA
X
X
X
X
X
X
X
X
X
Fundus 
autofluorescence
X
X
X
X
X
X
X
X
X
X

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Study Visit
Screening/
Baselinea
Day 0
Day 1
Day 7
Month 
1
Month 
2
Month 
3
Month 
6
Month 
9
Month 
12b 
Year 1
Month 
18 c
Month 
24 
Year 2 
c,d
ET 
Visite
Uns. 
Visitf
Visit Window
(±3d)
(±7d)
(±7d)
(±7d)
(±14d)
(±14d)
(±14d)
(±14d)
(±14d)
Visit Number
Visit 1
Visit 2g
Visit 3 g
Visit 4 g
Visit 5
Visit 
5.9
Visit 6
Visit 7
Visit 8
Visit 9
Visit 10
Visit 11
MAIA Microperimetryn
X
X
X
X
X 
X
X
X
X
X
X
Fundus photography
X
X
X
X
X
Visual fields (Octopus 
900 in Part II)o
X
X
X
X
X
X
Contrast sensitivity
X
X
X
X
X
X
Viral sheddingq
X
X
X
X
X
Immunogenicity 
samplingr
X
X
X
X
X
X
X
X
X
AE, SAE monitorings
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Concomitant 
medication, treatments, 
and procedures review
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Corticosteroid 
compliance reviewt
X
X
X
X
X
Randomization
X
Abbreviations: AE=adverse event; BCVA=best-corrected visual acuity; ET=early termination; ETDRS=Early Treatment of Diabetic Retinopathy Study; 
IOP=intraocular pressure; LOCS III =Lens Opacities Classification System III; LLVA= Low luminance visual acuity; SAE=serious adverse event; SD-
OCT=spectral domain optical coherence tomography; 
; 
All procedures will be performed for both eyes, unless otherwise specified. 
a.
The Screening/Baseline Visit must be performed within 12 weeks of Visit 2 
b.
Although the visit will still be considered out-of-window, if a subject in Part II is unable to attend the 12-month visit during the protocol-defined 
window, they should return to the site to complete this visit as soon as it is possible for them to do so. Delays will be identified as PDs on a case-by-case 
basis by the Sponsor based on information provided by the site; this will include but is not limited to scenarios such as site closure, travel bans, medical 
travel prohibitions, patient illness, etc.
c.
Visits 10 and 11 are for Part I subjects only

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d.
Although the visit will still be considered out-of-window, if a subject in Part I is unable to attend the 24-month visit during the protocol-defined 
window, they should return to the site to complete this visit as soon as it is possible for them to do so. Delays will be identified as PDs on a case-by-case 
basis by the Sponsor based on information provided by the site; this will include but is not limited to scenarios such as site closure, travel bans, medical 
travel prohibitions, patient illness, etc.
e.
An early termination (ET) visit is to be performed if a subject discontinues at any time. 
 
f.
If clinically indicated, subjects may need to return to the site for an unscheduled visit. At a minimum, the following assessments will be performed: full 
ophthalmic examination, BCVA, SD-OCT, microperimetry (if clinically feasible), fundus autofluorescence, AE/SAE monitoring, and concomitant 
medication, treatments, and procedures review
g.
Visits 2, 3, and 4 will be a telephone call only for subjects randomised to the control, untreated group. AE/SAE monitoring and concomitant medication, 
treatments, and procedures review will be assessed during the call. 
h.
Includes hematology and clinical chemistry
i.
To be conducted only if unavailable at Visit 1 
j.
Includes indirect ophthalmoscopy, slit lamp examination, IOP, anterior chamber and vitreous inflammation grading and LOCS III cataract grading
k.
Study eye only
l.
Part I subjects will take 1 mg/kg/day prednisone/prednisolone for a total of 10 days (beginning 2 days before the vector injection, on the day of 
injection, and then for 7 days); followed by 0.5 mg/kg/day for 7 days; 0.25 mg/kg/day for 2 days; and 0.125 mg/kg/day for 2 days (21 days in total). Part 
II subjects in treated groups will be given a 9-week course of oral prednisone/prednisolone and instructed to start taking the drug 3 days before Visit 2. 
See Section 8.8. 
m. Part I subjects perform BCVA assessments in triplicate at baseline, Month 12, Month 24, and at the Early Termination visit, when applicable. For Part II 
subjects only: if the BCVA value at Visit 1 (Screening/Baseline) is ≥ ± 10 letter gain or loss in the study eye compared to the previous XOLARIS study 
visit (if applicable), then BCVA must be repeated an additional 2 times, resulting in a total of 3 BCVA measures at Visit 1. 
In Part II subjects, if the BCVA value at Visit 1 (Screening/Baseline) is < ± 10 letter difference in the study eye compared to the previous XOLARIS 
study visit, then BCVA will be collected once and will not be repeated. If subject was not previously in XOLARIS study, BCVA assessments at baseline 
must be triplicate.
For all subjects who require triplicate BCVA testing, to facilitate the additional BCVA measures, this visit should be conducted over 2 days, with 
BCVA measured twice on Day 1 and once on Day 2 (prior to pupil dilation). All 3 BCVA values must be recorded in the eCRF. At screening, the 
highest score will be used to define subject eligibility.
n.
Subjects perform triplicate microperimetry only at baseline. The final microperimetry assessment will be used to determine eligibility. Microperimetry 
should be conducted at unscheduled visits, if clinically feasible. Microperimetry outputs will be sent to a CRC for review. Data will be generated and 
collated within the CRC and exported to the Sponsor or designee for inclusion in the study database.
o.
Triplicate at baseline. Octopus 900 perimeter is specified for visual field assessments only in Part II. Visual field outputs will be sent to a CRC for 
review. Data will be generated and collated within the CRC and exported to the Sponsor or designee for inclusion in the study database.
q.
Blood, tears (both eyes), saliva, and urine samples will be collected for the viral shedding assay.
r.
Immunogenicity sampling at the ET Visit is to be conducted only if visit occurs prior to Month 12 visit.
s.
AEs/SAEs will be collected from the time the subject provides written informed consent/assent through to the last study visit (or ET Visit if applicable). 
t.
Corticosteroid review is applicable only for treated subjects. 
u.
Part II only. 

CONFIDENTIAL
The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
1
Biogen MA Inc.
225 Binney Street
Cambridge, MA  02142
United States
Biogen Idec Research Limited
Innovation House
70 Norden Road
Maidenhead, Berkshire
SL6 4AY
United Kingdom
______________________________________________________________________
AMENDMENT SUMMARY
Biogen Protocol 274RP101 (NSR-RPGR-01)
A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa GTPase Regulator (RPGR)
XIRIUS Study
For Global Protocol Amendment: Version 11
Date: 1 Oct 2020
EUDRA CT Number: 2016-003852-60
Version 11 of the protocol has been prepared for this amendment, which supersedes Version 10, 
10 October 2019.

Amendment Summary for Protocol 274RP101 (NSR-RPGR-01), Version 11
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PRIMARY REASON FOR AMENDMENT
Two primary reasons for this amendment to Protocol 274RP101 (NSR-RPGR-01) are 1) to 
reduce the sample size and 2) remove the requirement for an interim analysis (IA). 
Regarding the first primary reason, the sections most affected by these changes are Section 13.1 
(Sample Size), and secondarily Sections 7.1 (Overall Study Design), Section 7.1.4 (Part II Dose 
Expansion), Section 7.2, (Number of Subjects).  This change in sample size required additional 
modifications to the planned Statistical Analyses. The sections most affected by the statistical 
analysis changes are Section 13.2 (Procedure for Accounting for Missing Data), Section 13.3.1 
(Safety Analysis Set), Section 13.3.2 (Intent to Treat Analysis Set), Section 13.4 (Descriptive 
Statistics), Section 13.5 (Demographics and Baseline Characteristics), Section 13.6 (Efficacy 
Analysis), Section 13.6.1 (Multiplicity Adjustment), Section 13.7.1 (Adverse Events), and 
Section 13.7.2 (Ocular Safety).
Regarding the second primary reason, the sections most affected by these changes are Section 
13.8 (Interim Analysis), and secondarily, Sections 7.1.4 (Part II, Dose-Expansion), Section 
12.2.6 (Data Monitoring Committee). 
New text is shown in bold type; deleted text is shown with a strikethrough.

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1.
PRIMARY REASON ONE
Section 13.1, Sample Size
In Part II, a sample size of 45 subjects, 15 in each of 3 groups (high-dose, low-dose and 
untreated), ensures 80% power at 0.05 significance level assuming that the treated arm has 50% 
probability of achieving ≥7 dB improvement at ≥5 loci at Month 3 vs. 5% in the untreated 
control arm. In Part II, the primary endpoint is the proportion of study eyes with ≥7 dB 
improvement from baseline at ≥5 of the 16 central loci of the 10-2 grid assessed by MAIA 
microperimetry at 12 months. A sample size of 10 subjects from a treatment group (either 
high dose or low dose), and 9 subjects from the untreated control group, will provide 
approximately 87% power, assuming the treatment group has a 50% response rate and the 
untreated group has a 5% response rate. The power calculation is based on Fisher Exact-
Boschloo test with a Berger-Boos correction of beta = 0.001, at a right-sided significance 
level of 0.10.
Rationale for reduction in sample size: 
Study drug expired end of September 2019, and it was not possible to extend the shelf-life, nor 
was there the possibility of using a new drug supply without causing a significant delay to the 
completion of this study.
The team performed an assessment and determined to close enrollment as of the last subject 
enrolled on 30 September 2019.  It was decided that 29 subjects will provide sufficient data to 
inform the next pivotal study.  
This change also affects text in Section 7.1 (Overall Study Design), 7.1.4 (Part II, Dose 
Expansion), and 7.2 (Number of Subjects).  This sample size change also triggered broad 
changes to the planned statistical analyses, affecting Section 13.2 (Procedures for Accounting for 
Missing Data), Section 13.3.1 (Safety Analysis Set), Section 13.3.2 (Intent to Treat Analysis 
Set), Section 13.4 (Descriptive Statistics), Section 13.5 (Demographics and Baseline 
Characteristics), and Section 13.6 (Efficacy Analysis). 

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Section 7.1, Overall Study Design
Now reads:
Part II will expand 2 doses, allowing for a broader assessment of the safety and efficacy of 
AAV8-RPGR with a larger sample size, including 45 approximately 30 subjects randomized 
1:1:1 to a high-dose, a low-dose, or an untreated arm.
Section 7.1.4, Part II, Dose expansion
Now reads:
Up to 45 From version 9.0 thereafter, approximately 30 additional subjects will be 
randomized in a 1:1:1 allocation ratio to a high-dose group (2.5 × 10^11 gp), a low-dose group (5 
× 10^10 gp), and an untreated group.
Section 7.2, Number of Subjects
Now reads:
Overall, the study is expected to enroll approximately 63 48 subjects: 18 in Part I and up to 
approximately 45 30 in Part II under 1:1:1 randomization scheme.  See Section 13.1 for 
rationale.  
Section 13.2 Procedures for Accounting for Missing Data
Now reads:
Safety and efficacy data will be analysed on observed data only. Missing data will not be 
imputed.
Part I is an open-label study. For efficacy endpoints, observations collected within 6 
months of the last visit window will be included in the primary analysis. and. Efficacy 
endpoints will be summarized on observed data and no imputation will be performed. 
Safety endpoints will be analysed on observed data and no imputation will be performed.
Part II is a randomized and double-masked study. For efficacy endpoints, observations 
collected within 6 months of the last visit window will be included in the primary analysis. 
Additional imputation approaches will be specified in the SAP. Safety endpoints will be 
analysed on observed data and no imputation will be performed.

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Section 13.3.1, Safety Analysis Set
Now reads:
The Safety Analysis Set will be the primary population for demographics, baseline 
characteristics and safety analyses used for all analyses in Part I.
For Part II, the Safety Analysis Set will consist of all subjects who are randomised , under both 
the 2- and the 3-arm randomisation schedules and receive study treatment when randomized 
to active treatment, or attend Visit 2 (telephone call) when randomized to control (no 
treatment).  Safety summaries of Part II will use the Safety Analysis Set and subjects will 
be analysed based on the actual treatment received. The Safety Analysis Set will be the 
primary population for demographics, baseline characteristics and safety analyses. Subjects will 
be analysed based on the actual treatment received.
Section 13.3.2 Intent to Treat Analysis Set
Now reads:
The intent-to-treat (ITT) Analysis Set will consist of all Part II subjects who are randomised, 
under the 3-arm randomisation schedules.  The ITT Analysis Set will be used for the efficacy 
analyses. The efficacy summaries of Part II will be generated using the ITT Analysis Set. 
Subjects will be analysed based on the treatment to which they were randomised. 
The modified intent-to-treat (mITT) Analysis Set will include all Part II subjects who are 
randomised under the 3-arm randomisation schedule and who receive study treatment (or the 
phone call for those in the untreated control group) and who have baseline microperimetry data 
and at least 1 post-baseline microperimetry data in the study eye. The mITT Analysis Set will be 
used for supportive and sensitivity analysis for Part II primary and secondary efficacy endpoints. 
Subjects will be analysed based on the treatment to which they were randomised.
Section 13.4 Descriptive Statistics
Now reads:
Summary statistics will be presented for both eyes (Study Eyes versus Fellow Eyes).  No formal 
statistical comparison will be performed in Part I, and statistical tests will be conducted for the 
efficacy endpoints in Part II.  For categorical/binary data, the number and proportion of subjects 
pertaining to each category will be presented over time with its 95% confidence interval (CI). 
Continuous data will be summarised over time using mean, and its 95% CI, standard deviation, 
median, minimum and maximum. 95% CIs will be 2-sided. Summaries will be generated by dose 
and overall, in Part I and, by group (high-dose, low-dose, untreated) in Part II. Formal statistical 
testing will be conducted for the primary endpoint in Part II. Continuous variables and 
their change from baseline will be summarized using descriptive statistics (number of 

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subjects [n], mean, standard deviation, median, minimum, maximum, first and third 
quartiles, fifth and ninety-fifth percentiles). The confidence interval (CI) is of the mean and 
the mean change from baseline at each visit may be provided where applicable. For 
categorical variables, the number and proportion of subjects pertaining to each category 
will be presented over time. The CIs of the proportion may be provided where applicable. 
will be computed using the Clopper-Pearson method.
Section 13.5, Demographics and Baseline Characteristics
Now reads:
Demographics and baseline ocular characteristics will be summarised by using for the Safety 
Analysis Set in both Part I and Part II. and the full analysis set for Part I and Part II separately.
Section 13.6 Efficacy Analysis
Now reads:
Efficacy assessments are ocular in nature and therefore will be tabulated by eye (Study Eye and 
Fellow Eye). In Part I, efficacy data endpoints will be summarised on observed data using 
descriptive statistics only (described in Section 13.4). In Part II, efficacy endpoints will be 
summarized on observed data using descriptive statistics. Additional analyses for handling 
missing data will be provided for the primary endpoint and selected secondary endpoint. 
This will be done for each cohort in Part I, and each arm group in Part II.
For each subject, data collected within 6 months of the last visit window will be included in 
the primary analysis, as described in greater detail in the SAP. 
Improvement in retinal sensitivity and change from baseline in retinal sensitivity will be 
tabulated by visit and by eye in each Part, and be compared between the randomized groups in 
Part II by visit for the study eye.
At final analysis in Part II, the primary endpoint, which is defined as the proportion of 
study eyes with with improved retinal sensitivity, for both the center grid (i.e., the central 16 
loci) and the entire grid (i.e., all 68 loci), ≥7 dB improvement from baseline at ≥5 of the 16 
central loci at 12 months, will be compared between study arms treatment groups (high dose vs 
untreated; low dose vs untreated) using the Fisher Exact-Boschloo test with a Berger-Boos 
correction of beta=0.001 (Berger 1994).  In addition, the difference in proportions between study 
arms will be presented with its corresponding 95% CI calculatedThe CIs for the difference in 
proportions between treatment groups will be presented by Miettinen and Nurminen (Miettinen 
1985) method. 
For the continuous variables of mean sensitivity, BCVA, and LLVA in Part II, the primary 
analysis to handle missing data uses a mixed model repeated measures (MMRM) model. 

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The mean change from baseline will be analyzed using fixed effects of treatment group, 
study visit, study-visit-treatment interaction, and baseline value.  
Change from baseline in mean sensitivity, in both the center grid and the entire grid, will be 
compared between study arms using an ANCOVA model including baseline value and study arm 
(high dose, low-dose, and untreated) as covariates. The difference in means between study arms, 
and its 95% CI, will be derived from the same ANCOVA model.
Section 13.7.1, Adverse Events
Now reads:
The SAEs, severity, and relationship to study drug/procedure will be also summarized. A 
by-subject listing of SAEs and DLTs (Part I only) will be provided. Similar summaries will 
be produced for study drug/procedure-related AEs, AEs leading to discontinuation and SAEs.  
AEs will also be summarised by maximum severity, relationship to study drug/procedure and 
time to onset.
For Part I only, A a by-subject listing of DLTs will be prepared.
Section 13.7.2 Ocular Safety Evaluation
Now reads: 
The number of subjects with a 5, 10- and 15-letter decrease from baseline in BCVA will be 
tabulated by visit and by eye.

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2.
PRIMARY REASON TWO
Section 13.8 Interim Analysis
Now reads:
  
In Part II, after all subjects complete the 3-month visit, a single administrative IA will may be 
performed. by an independent DMC.  The DMC will review the accrued safety and efficacy data.  
A small group of unmasked Sponsor personnel, who will not be involved in the conduct of the 
study moving forward, will have access to unmasked data for this administrative IA to enable 
regulatory interactions and planning for phase 3 initiation.  The details of the roles and 
responsibilities of the Part II DMC are provided in the DMC charter, and the full details of 
masking are provided in the study Masking Plan. 
If this IA is performed, The the study will continue as planned in a masked fashion.  A final 
analysis will be conducted at the end of the study, i.e., after all subjects complete the study. The 
end of the study is defined as the date the last subject completes his final-visit assessments (or 
early termination [ET] assessments in the event of premature discontinuation) or the date of last 
data collection if the last subject is lost to follow-up.
Rationale: The interim analysis was determined to no  longer be necessary.
This change also affects Section 7.1.4, Part II: Dose Expansion
Now reads:
After all Part II subjects complete the 3-month visit During Part II, a single administrative IA 
will may be conducted. If this IA is performed, the study will continue as planned in a masked 
fashion.  
Section 9.6, Study Masking
Now reads:
After allDuring Part II, subjects complete the 3-month visit, one administrative IA will may be 
performed. by an independent DMC, who will review the accrued safety and efficacy data.  A 
small group of unmasked Sponsor personnel, who will not be involved in the conduct of the 
study moving forward, will have access to unmasked data for this administrative IA to enable 
regulatory interactions and planning for phase 3 initiation. If this IA is performed, the study 
will continue as planned in a masked fashion. 
The operations team, the investigators, medical monitor, and other personnel who will continue 
to be involved in the daily operation of the study, as well as the subjects, will continue to be 
masked to the subjects’ dose level assignment and outcomes of the IA until study completion to 

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minimise any operational bias.  Furthermore, the clinical assessors will continue to be masked to 
the treatment assignment. The full details of masking are provided in the study Masking Plan.
Section 12.2.6, Data Monitoring Committee
Now reads:
In Part II, DMC will be held to review safety and assess benefit/risk during the course of 
the study.
After allDuring Part II subjects complete the 3-month visit, an administrative IA will may be 
performed. If one IA is performed, the study will continue as planned in a masked fashion. 
by an independent DMC, who will review the accrued safety and efficacy data.  A small group of 
unmasked Sponsor personnel, who will not be involved in the conduct of the study moving 
forward, will have access to unmasked data for this administrative IA to enable regulatory 
interactions and planning for phase 3 initiation. Following the administrative IA, the DMC will 
continue to meet, as described in the DMC Charter.
Section 13.6.1, Multiplicity Adjustment
Now reads:
In Part II, a single administrative IA is may be included to facilitate the planning of Phase 3 
activities.
The final analysis will be conducted at 0.05 two-sided level for the primary endpoint. 
At final analysis, the primary endpoint will be tested using Hochberg’s (Hochberg 1988) 
step-up method with familywise error rate controlled at < 0.10 (one-sided).  The study will 
be declared positive if either dose or both doses achieve statistical significance.

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SUMMARY OF MAJOR CHANGES TO THE PROTOCOL
Changes to the protocol are presented chronologically. New text is shown in bold type; deleted 
text is shown with a strikethrough.
Synopsis
The synopsis was revised to reflect changes made throughout the protocol.
Section 5.4 
Change: Interim data were presented in the original protocol. This is now removed.
Now reads:
Interim (4-week) rResults from the sponsor’s toxicity study also indicate that administration of 
the same vector (AAV8 RPGR) is well tolerated in male C57BL/6J mice at dose levels of 
1×10^9 and 3.54×10^9 gp/eye; interim (35-day) results from the sponsor’s biodistribution study 
also support a lack of toxicity.
Rationale: The nonclinical toxicity studies are now complete. 
Section 6.2.1.2, Secondary and Exploratory Endpoints, Part I
Change: Removed Month 9 from the timepoints at which this endpoint will be assessed. 
Now reads:
• Change from baseline in fundus autofluorescence at 1, 2, 3, 6, 9 and 12 months
Rationale: One time point (month 9) was removed from the endpoint analysis regarding 
autofluorescence as it was added in error. This measure is not assessed at Month 9. 

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Section 6.2.2.3 Secondary Endpoints 
Change: The secondary endpoints have been updated to separate the central 16-loci 
microperimetry mean change from baseline from the 68-loci microperimetry mean change from 
baseline. Previously, these 2 separate endpoints were not defined. Also, visual field-related 
endpoints at 1, 2 and 9 months were listed in error.  Visual field is not tested at these visits. 
Now reads: 
• Change from baseline in retinal sensitivity at the central 16 loci assessed by MAIA 
microperimetry at 1, 2, 3, 6, 9, and 12 months
• Change from baseline in retinal sensitivity at 68 loci assessed by MAIA microperimetry at 1, 
2, 3, 6, 9, and 12 months
• Change from baseline in visual field assessed by Octopus 900 perimeter at 1, 2, 3, 6, 9, and 12 
months
Rationale: Microperimetry is the most important efficacy endpoint in the study. More granularity 
was needed as multiple analyses will be conducted on this measure.
Section 6.2.2.4 Exploratory Endpoints
Change: 
 
Now reads:
• 
Rationale: 
 
 
Section 7.1 Overall Study Design
Change: additional time points were added for when microperimetry and safety and secondary 
efficacy assessments will be evaluated.
Now reads:
Baseline in microperimetry, evaluated at 3 12 months, and safety and secondary efficacy 
evaluated at 1-, 2-, 3-, 6-, 9-, and 12-months post-treatment.
Rationale: These time points were omitted in error.

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Section 7.1 Overall Study Design
Change: Text added regarding missed visits.
Now reads:
Although the visit will still be considered out-of-window, if Part I subjects are unable to 
attend their final 24-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. Delays will be 
identified as protocol deviations (PDs) on a case-by-case basis by the Sponsor based on 
information provided by the site; this will include but is not limited to scenarios such as site 
closure, travel bans, medical travel prohibitions, patient illness, etc.
A Part II subject is considered to have completed the study if he completes the Month 12 
assessments.  Although the visit will still be considered out-of-window, if Part II subjects are 
unable to attend their final 12-month visit during the protocol-defined window, they should 
return to the site to complete this visit as soon as it is possible for them to do so. Delays will 
be identified as protocol deviations (PDs) on a case-by-case basis by the Sponsor based on 
information provided by the site; this will include but is not limited to scenarios such as site 
closure, travel bans, medical travel prohibitions, patient illness, etc.
Rationale: Instructions are provided in the case of missed final visits. If a subject misses the 12- 
or 24-month visit (for Parts I and II ), the site is instructed to bring the subject back to complete 
the 12- or 24-month visit assessments when it is possible to do so, even if this visit will be out-
of-window.
This change also affects Section 7.1.2, Part I, Dose Escalation Study, Section 7.1.4, Part II: 
Dose-Expansion, Section 10.10, Visit 9, Section 10.12, Visit 11.
Section 7.1.2, Part I, Dose Escalation Study
Although the visit will still be considered out-of-window, if Part I subjects are unable to 
attend their final 24-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so.  This will be 
considered their 24-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited 
to scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
Section 7.1.4, Part II Dose Expansion
Although the visit will still be considered out-of-window, if Part II subjects are unable to 
attend their final 12-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 12-month visit. Delays will be identified as PDs on a case-by-case basis by 

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the Sponsor based on information provided by the site; this will include but is not limited 
to scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
Section 10.10, Visit 9
Although the visit will still be considered out-of-window, if Part II subjects are unable to 
attend their final 12-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so. This will be 
considered their 12-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited 
to scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
Section 10.12, Visit 11
Although the visit will still be considered out-of-window, if Part I subjects are unable to 
attend their final 24-month visit during the protocol-defined window, they should return to 
the site to complete this visit as soon as it is possible for them to do so.  This will be 
considered their 24-month visit. Delays will be identified as PDs on a case-by-case basis by 
the Sponsor based on information provided by the site; this will include but is not limited 
to scenarios such as site closure, travel bans, medical travel prohibitions, patient illness, etc.
Section 17.1, Schedule of Study Procedures, Footnotes b and d
Now read:
b.
Although the visit will still be considered out-of-window, if a subject in Part II is 
unable to attend the 12-month visit during the protocol-defined window, they should return 
to the site to complete this visit as soon as it is possible for them to do so. Delays will be 
identified as PDs on a case-by-case basis by the Sponsor based on information provided by 
the site; this will include but is not limited to scenarios such as site closure, travel bans, 
medical travel prohibitions, patient illness, etc.

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d.
Although the visit will still be considered out-of-window, if a subject in Part I is 
unable to attend the 24-month visit during the protocol-defined window, they should return 
to the site to complete this visit as soon as it is possible for them to do so. Delays will be 
identified as PDs on a case-by-case basis by the Sponsor based on information provided by 
the site; this will include but is not limited to scenarios such as site closure, travel bans, 
medical travel prohibitions, patient illness, etc.
Section 7.3 Discussion of Study Design and Dose Selection
Change: The NOAEL was changed from greater than to equal to 3.54 × 10^9.
Now reads:
The NOAEL was determined to be greater than 3.54 × 10^9 gp/eye in mice, providing a 700-fold 
safety margin compared to the starting dose.
Rationale: The NOAEL was incorrectly stated.
Section 9.6, Study Masking
Change: Removed masked assessors
In Part II, ophthalmic assessments that will be used as efficacy endpoints (BCVA, LLVA, 
microperimetry, contrast sensitivity 
) will be conducted by appropriately qualified 
masked assessors
Rationale: Efficacy assessments are not masked throughout the study, only at certain timepoints.  
The table linked to this text specifies which timepoints and is therefore correct. However, it has 
been removed from this statement for accuracy. 
Section 15.4 Time and Schedule of the Study
Now reads:
Section 15.4 Time and Schedule End of the Study 
Rationale: This section did not provide a clear definition of end of study.
Added a second paragraph: 
The end of the study is defined as the date the last subject completes his final-visit 
assessments, or early termination [ET] assessments in the event of premature 
discontinuation, or the date of last data collection if the last subject is lost to follow-up.
Rationale: While this definition was also present in Section 7.1, it was not clearly defined here.

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SUMMARY OF MINOR CHANGES TO THE PROTOCOL
The following minor changes were made to the protocol, as appropriate:

The version number and date were updated throughout the protocol.

Sponsor Information was updated.

Safety reporting email address was updated

List of Abbreviations was updated.

Typographical errors and formatting were corrected.

Genome particles (gp) as a unit of measure was updated to vector genomes (vg).

Reference list has been updated

Footnotes in Table of Procedure updated

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LIST OF ABBREVIATIONS
Abbreviation or Term
Definition
AAV
adeno-associated virus
AAV8-RPGR
AAV8 virus particle encapsulating 3.46 kb cDNA for the 
coRPGR gene
AE
adverse event
BCVA
best-corrected visual acuity
BGH
bovine growth hormone
BSS
balanced salt solution
cDNA
complementary deoxyribonucleic acid
CI
confidence interval
coRPGR
codon optimised human cDNA encoding RPGR
COVID-19
coronoavirus disease 2019
DLT
dose-limiting toxicity
DMC
Data Monitoring Committee
ERG
electroretinography
ET
early termination
ETDRS
Early Treatment of Diabetic Retinopathy Study
FDA
Food and Drug Administration
gp
genome particles
ICH
International Council for Harmonisation
IA
interim analysis
ITT
Intent to Treat
LLVA
low luminance visual acuity
LOCS III
lens opacities classification system III
MAIA
macular integrity assessment
MMRM
Mixed model repeated measures
RP
retinitis pigmentosa 
RPGR
retinitis pigmentosa GTPase regulator
Rpgr
murine homologue of human RPGR
SAP
Statistical Analysis Plan
SAE
serious adverse event
VA
visual acuity
XLRP
X-linked retinitis pigmentosa

 
AAV8-RPGR 
Protocol: NSR-RPGR-01 
Version 9.0 and Version 10 
14 Aug 2019 and 10 October 2019  
 
CONFIDENTIAL 
Page 1 of 30 
 
SUMMARY OF CHANGES 
CLINICAL STUDY PROTOCOL  
NSR-RPGR-01 
AAV8-RPGR 
A Dose Escalation (Phase 1), and Dose Expansion 
(Phase 2/3) Clinical Trial of Retinal Gene Therapy for X-
linked Retinitis Pigmentosa Using an Adeno-Associated 
Viral Vector (AAV8) Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
 
XIRIUS Study, Version 9 and Version 10 
SPONSOR: 
NightstaRx Ltd 
2nd Floor 
10 Midford Place 
London W1T 5BJ UK 
Telephone:  +44 (0) 1628 501000 
ORIGINAL PROTOCOL DATE:  
27 Sep 2016 
VERSION 2:  
 
 
 
01 Dec 2016 
VERSION 3:  
 
 
 
26 May 2017 
VERSION 4:  
 
 
 
15 Dec 2017 
VERSION 5:  
 
 
 
16 Jan 2018  
VERSION 6:  
 
 
 
18 MAY 2018  
VERSION 7:  
 
 
 
16 Nov 2018 
VERSION 7.1 
 
 
 
10 Dec 2018 (Administrative Amendment) 
VERSION 8.0 
 
 
 
18 Dec 2018 
VERSION 8.1 
 
 
 
08 Mar 2019 (Administrative Amendment) 
VERSION 9.0 
 
 
 
14 Aug 2019 
VERSION 10 
 
 
 
10 October 2019 
 
 

 
AAV8-RPGR 
Protocol: NSR-RPGR-01 
Version 9.0 and Version 10 
14 Aug 2019 and 10 October 2019  
 
CONFIDENTIAL 
Page 3 of 30 
 
RATIONALE FOR SUBSTANTIAL AMENDMENT 
PROTOCOL AMENDMENT XIRIUS VERSION 9.0 
 
The most substantial change to the protocol is addition of an administrative interim analysis (IA) 
after all Part II subjects complete 3 months of post-treatment follow-up. This activity will enable 
a data readout and Phase 3 planning / regulatory interactions as discussed in prior regulatory 
agency meetings.  Results of the interim analysis will then be presented to the regulatory 
agencies (both European Medicines Agency [EMA] and Food and Drug Administration [FDA]) 
for continued alignment on the acceptability of approach taken in evaluating the safety and 
efficacy of AAV8-RPGR.  
Inclusion and exclusion criteria have also been modified.  
• The requirement that subjects have a measurable ellipsoid zone (EZ) on optical coherence 
tomography (OCT) imaging has been removed to allow the broader study of X-linked 
retinitis pigmentosa (XLRP) subjects who do not have a measurable EZ. 
• Documentation of a positive genetic screen now specifies that a pathogenic mutation 
must be present for clarification of test results from genetic screening. 
• Best-corrected visual acuity (BCVA) now must achieve ≥34 letters in both eyes and not 
just the study eye to assure that no monocular or subjects with very poor vision in the 
fellow eye are enrolled. 
• Exclusion has been added for subjects who are unsuitable candidates for surgery for any 
reason. 
Study masking language has been improved and the specific assessments that must be taken in a 
masked fashion are better described. Also, the maintenance of masking of study teams during the 
interim analysis proceedings are described.  
The assessment 
 has been removed 
from the study due to lack of operational feasibility.  
Several changes to the Statistical Analysis and endpoints have been included: 
• After meetings with both the EMA and FDA, the primary endpoint, microperimetry, has 
been clarified as a categorical endpoint that identifies the improvements in 
microperimetry at individual loci instead of overall mean retinal sensitivity. Therefore, 
the increase of ≥7 decibel (dB)  in ≥5 central loci has been selected as the microperimetry 
endpoint. This same level of change in all 68 loci has become a new secondary endpoint.  
In agreement with the EMA, 
 have 
been de-ranked to exploratory endpoints. 
• The safety analysis set has been clarified as including all treated subjects from both 2-arm 
and 3-arm randomization schedules, including subjects treated under previous versions of 
the protocol. However, the definition of the Intent to Treat (ITT) population has been 
clarified to include only 3-arm randomized subjects. The modified ITT population is also 

 
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described as the population of treated and not only randomized subjects; this population 
will be used for sensitivity and supportive analysis.  
• Specific details of the efficacy analysis, including Berger-Boos correction, have been 
added now that the Statistical Analysis Plan has been completed, as well as clarifying 
why multiplicity adjustments are not needed.  
• The administrative interim analysis is described.  
Protocol template language regarding safety assessments has been updated.  The definition of 
serious adverse events, and reporting of SAEs are better defined and consistent with other 
protocols. The definition, particularly regarding the timing, of vision loss post-treatment as an 
SAE is better defined.  
The Data Monitoring Committee for Part II, which will participate in the interim analysis, is now 
described. 
Additional minor changes are defined in the following Summary of Changes table.  
 
RATIONALE FOR SUBSTANTIAL AMENDMENT 
PROTOCOL AMENDMENT XIRIUS VERSION 10.0 
 
In all previous versions of the protocol, a maximum time period of 8 weeks was allowed between 
the Baseline / Screening Visit and the day of surgery, Visit 2.  This has been changed in Version 
10 to a window of 12 weeks between screening and surgery in order to provide operational 
flexibility for the sites and investigators and to minimize patient burden for participation in the 
study. This change in no way affects the safety and efficacy of the drug, the outcomes of the 
study, as well as the ultimate analyses of the datasets. 
 
 

 
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Section Changed 
Original Text (crossed out) 
Amended Text (in red) 
Rationale 
A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene Therapy for X-
linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) Encoding Retinitis 
Pigmentosa GTPase Regulator (RPGR) 
Version 9.0 
Summary of Changes 
14 August 2019 
Title Page 
Telephone:  +44 (0) 207 062 
27771628 501000 
Telephone:  1628 501000 
New telephone 
number  
Sponsor Approval, 
Page 2 
, MD 
 
 
, MD 
 
New signatory 
Contact Information  
Page 5 
 
 
 
 
 
 
Serious adverse events, dose-
limiting toxicities, and Pregnancy 
Notification Forms should be 
emailed to 
 
For further information, refer to 
Section 12.0, Assessment of Safety. 
 
Additional contact 
information is available in the 
Site Operations Manual. 
Protocol 
Template 
language has 
been changed 
across all studies 
and protocols.  
Synopsis 
Part I Secondary 
Endpoints 
Page 6 
 
Part I Secondary Endpoints:  
1, 3, 6, 9, 12, 18 and 24 
months 
Added 1 and 9 
month 
posttreatment to 
assessment 
endpoints 
Synopsis  
Part II 
Primary Endpoint 
Page 6 
Part II  
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
The primary efficacy endpoint 
is the proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of the 16 
central loci of the 10-2 grid 
assessed by Macular Integrity 
Assessment (MAIA) 
microperimetry at 12 months. 
Newly defined 
primary endpoint 
in alignment with 
feedback from 
regulatory 
agencies 
Synopsis 
Part II 
 
at 1, 2, 3, 6, 9, and 12 months 
 
Added post-
treatment time 
point assessments 

 
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Original Text (crossed out) 
Amended Text (in red) 
Rationale 
Secondary 
Endpoints 
Page 6 
to secondary 
endpoints 
 
• Proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of 16 
central loci of the 10-2 grid 
assessed by MAIA 
microperimetry at 1, 2, 3, 6, 
and 9 months 
• Proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of 68 
loci of the 10-2 grid 
assessed by MAIA 
microperimetry at 1, 2, 3, 6, 
9, and 12 months 
 
Added secondary 
endpoints in line 
with primary 
endpoint 
Change from baseline in SD-OCT at 
3, 6, and12 months 
Change from baseline in fundus 
autofluorescence at 3, 6, and 12 
months 
 
 
Removed these as 
secondary 
endpoints, in 
agreement with 
EMA 
Synopsis 
Part II 
Exploratory 
Endpoints 
Page 6 
 
 
 
 
 
 
Added as 
exploratory 
instead of 
secondary 
endpoints, in 
agreement with 
EMA 
 
 
 
 
 
 
 
 
 
 
 
Added timepoints 
to exploratory 
endpoints 

 
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Rationale 
Synopsis 
Study Design 
Page 7 
In Part II, all subjects will be treated 
at the time of surgery with up to 1 
mL of triamcinolone (40 mg/mL), 
placed behind the globe via a deep 
sub-Tenon approach.  All subjects 
will also be given a 9-week course 
of oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, 
followed by 6 weeks of tapering 
doses. The dose regimen is adjusted 
for pediatric subjects treated in Part 
II (see Section 9.8) . 
In Part II, all adult subjects 
will be given a 9-week course 
of oral corticosteroid starting 
3 days before surgery: 21 
days at 60 mg, followed by 6 
weeks of tapering doses. The 
dose regimen is adjusted for 
pediatric subjects treated in 
Part II (see Section 9.8) 
Subjects may also be treated 
at the time of surgery with up 
to 1 mL of triamcinolone (40 
mg/mL), administered via a 
deep sub-Tenon approach. 
Clarified that 
triamcinolone is 
optional treatment  
Synopsis  
Study Design 
Page 7-8 
 
To further minimise potential 
bias of the treated and non-
treated eye evaluations, all 
subjective ophthalmic 
assessments at the 
Screening/Baseline Visit 
(Visit 1) and from Month 3 
(Visit 6) onwards will be 
conducted by an assessor who 
is masked to treated eye and 
treated vs. untreated control 
group. 
Clarified that 
masking is to 
both treatment 
group and eye 
treated 
 
After all Part II subjects 
complete the 3-month visit, an 
administrative interim 
analysis (IA) will be 
conducted. 
Added IA 
 
At study completion, treated 
subjects in Part II will be 
invited to participate in a 
separate long-term follow-up 
study that will collect efficacy 
and safety data up to 5 years 
from surgery. 
Clarified that 
extension study is 
for treated 
subjects only 
Synopsis 
Number of subjects 
planned 
Page 9 
 
 
the study is expected to enroll 
approximately 63 subjects: 18 
in Part I and up to 45 in Part 
II  
Added flexibility 
in final sample 
size of Part II 
Synopsis 
 
Subject / parent / legal 
guardian (if applicable) is 
Added legal 
guardian and 

 
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Amended Text (in red) 
Rationale 
Inclusion Criteria 
Part II 
Page 9 
willing and able to provide 
informed consent/assent for 
participation in the study 
 
assent language 
for minors 
Documentation of a non-
synonymous mutation in the RPGR 
gene 
 
Documentation of a 
pathogenic mutation in the 
RPGR gene 
 
Clarified genetic 
testing  
Have a BCVA in the study eye that 
meets the following criteria: 
 
Have a BCVA in both eyes 
that meets the following 
criteria: 
 
To prevent poor 
fellow-eye vision 
or monocular 
subjects from 
enrolling 
Synopsis 
Exclusion Criteria 
Page 9 
 
Are unwilling to use barrier 
contraception methods (if 
applicable), or abstain from 
sexual intercourse, for a 
period of 3 months 
Added 
clarification 
 
c. unsuitability for retinal 
surgery 
Added subsection 
c to list of general 
exclusions so to 
prevent subjects 
who are 
unsuitable 
candidates for 
surgery from 
enrolling 
Synopsis 
Criteria for 
Evaluation 
Page 10 
 
 
 
 
 
Synopsis 
Statistical 
Methodology 
Page 10 
 
After all subjects in Part II 
complete the 3-month visit, an 
administrative IA will be 
conducted.  The study will 
continue as planned.  A final 
analysis will be conducted 
after all subjects have 
completed their final visit or 
are lost to follow-up. 
Added IA to 
enable End of 
Phase 2 
interactions with 
regulators and 
phase 3 planning 
as discussed with 
regulatory 
agencies 
Fisher’s exact test will be utilized 
for the comparisons of binary 
endpoints, and T-test will be 
The proportion of eyes with 
improved retinal sensitivity 
will be compared between 
study arms (high dose vs 
Added statistical 
analysis of new 
primary endpoint; 
removed previous 

 
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Rationale 
employed for the comparisons of 
continuous endpoints. 
untreated; low dose vs 
untreated) using the Fisher 
Exact-Boschloo test with a 
Berger-Boos correction of 
beta=0.001 (Berger 1994).  In 
addition, the difference in 
proportions between study 
arms will be presented with 
its corresponding 95% CI 
calculated using the method 
of Miettinen and Nurminen 
(Miettinen 1985).  Change 
from baseline in mean 
sensitivity will be compared 
between study arms using an 
ANCOVA model including 
baseline value and study arm 
(high dose, low-dose, and 
untreated) as covariates.  The 
difference in means between 
study arms, and its 95% CI, 
will be derived from the same 
ANCOVA model. 
language 
regarding Fisher’s 
exact test. 
Abbreviations and 
Definitions 
Page 16 
 
 
 
 
 
EZ 
ellipsoid zone 
Added EZ  
Section 5.0 
Introduction 
5.1 X-Linked 
Retinitis 
Pigmentosa 
Page 18 
 
 
Minor changes to 
text for 
clarification 
Section 6.2.1.2 
Part I Secondary 
Endpoints 
Page 22 
 
Part I Secondary Endpoints:  
1, 3, 6, 9, 12, 18 and 24 
months 
Added 1 and 9 
month 
posttreatment to 
assessment 
endpoints 
Section 6.2.2.1 
Part II 
Primary Efficacy 
Endpoint 
Page 22 
Part II  
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
The primary efficacy endpoint 
is the proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of the 16 
central loci of the 10-2 grid 
assessed by Macular Integrity 
Assessment (MAIA) 
microperimetry at 12 months. 
Newly defined 
primary endpoint 
in alignment with 
regulators 

 
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Rationale 
Section 6.2.2.3 
Part II 
Secondary 
Endpoints 
Page 22 
 
at 1, 2, 3, 6, 9, and 12 months 
 
Added post-
treatment time 
point assessments 
to secondary 
endpoints 
Change from baseline in SD-OCT at 
3, 6, and 12 months 
Change from baseline in fundus 
autofluorescence at 3, 6, and 12 
months 
 
• Proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of 16 
central loci of the 10-2 grid 
assessed by MAIA 
microperimetry at 1, 2, 3, 6, 
and 9 months 
• Proportion of study eyes 
with ≥7 dB improvement 
from baseline at ≥5 of 68 
loci of the 10-2 grid 
assessed by MAIA 
microperimetry at 1, 2, 3, 6, 
9, and 12 months 
 
Added secondary 
endpoint in line 
with primary 
endpoint 
deranked 
 
to 
exploratory in 
agreement with 
EMA 
Section 6.2.2.4 
Exploratory 
Endpoints 
Page 23 
 
 
 
 
 
 
 
 
 
Added to 
exploratory, 
removed from 
secondary 
 
 
 
 
 
 
 
 
Added timepoints 
to exploratory 
endpoints 
Section 7.1  
Overall Study 
Design 
Page 24 
 
Under version 6 of the 
protocol, Part II subjects were 
to be randomised into 2 active 
groups with a 2:1 allocation 
ratio (high dose [2.5 × 10^11 
Added language 
on how the 
subjects 
randomized under 
previous versions 

 
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Rationale 
gp] : low dose [5 × 10^10 
gp]).  Any subject randomised 
under this version will be 
followed for 12 months with 
the ongoing visit schedule and 
the data will be analysed 
separately (i.e., included in 
the Safety Analysis Set but 
not in the Intent to Treat Set, 
See Section 13.3).   
of the protocol 
will be followed 
 
At study completion, all Part I 
subjects and treated subjects 
in Part II will be invited to 
participate in a long-term 
follow-up study that will 
collect efficacy and safety 
data up to 5 years from 
surgery. 
Clarified that 
only treated 
subjects will be 
followed in 
extension study 
 
Once a subject has been 
randomised, a change in 
“study eye” designation is not 
permitted. 
Added 
clarification not 
permitting change 
in study eye 
 
 
 
 
After all Part II subjects 
complete the 3-month visit, an 
administrative interim 
analysis (IA) will be 
conducted.  See Section 13.8 
for further details. 
Added 
description of IA 
Section 7.1.3  
Part II Dose 
Expansion, Version 
6 
 
Part II Dose-Expansion, 
Version 6  
Under version 6 of the 
protocol, Part II subjects were 
to be randomised into 2 active 
groups with a 2:1 allocation 
ratio (high dose [2.5 × 10^11 
gp] : low dose [5 × 10^10 
gp]).  Any subject randomised 
under this version will be 
followed for 12 months with 
the ongoing visit schedule and 
the data will be analysed 
separately (i.e., included in 
Added section on 
follow-up of 
subjects from 
version 6 of 
protocol 

 
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Rationale 
the Safety Analysis Set but 
not in the Intent to Treat Set, 
See Section 13.3).   
Enrollment under Version 6.0 
has been superseded by the 3-
arm randomisation ongoing 
since Version 7.  
Section 7.1.4 
Part II Dose 
Expansion, Version 
9.0 
 
After all Part II subjects 
complete the 3-month visit, an 
administrative IA will be 
conducted.   
The study will continue as 
planned. A final analysis will 
be conducted at the end of the 
study, i.e., after all subjects 
complete the study.  The end 
of the study is defined as the 
date the last subject completes 
his final-visit assessments (or 
early termination [ET] 
assessments in the event of 
premature discontinuation) or 
the date of last data collection 
if the last subject is lost to 
follow-up. See Section 13.8 
for further details. 
Added 
description of IA; 
clarified the end 
of study 
definition 
Section 7.2 
Number of Subjects 
Page 28 
 
Overall, the study is expected 
to enroll approximately 63 
subjects: 18 in Part I and up to 
45 in Part II.   
Updated sample 
size to allow for 
flexibility in final 
sample size of 
Part II 
Part 8.2.1 Inclusion 
Criteria 
Page 30 
 
Subject / parent / legal 
guardian (if applicable) is 
willing and able to provide 
informed consent/assent for 
participation in the study 
Added legal 
guardian and 
assent for minors 
 
Documentation of a non-
synonymous mutation in the RPGR 
gene 
 
Documentation of a 
pathogenic mutation in the 
RPGR gene 
 
Clarified genetic 
testing 
 
Have a BCVA in the study eye that 
meets the following criteria: 
Have a BCVA in both eyes 
that meets the following 
criteria: 
To prevent poor 
fellow-eye vision 
or monocular 
subjects from 
enrolling 

 
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Amended Text (in red) 
Rationale 
Section 8.3  
Exclusion Criteria, 
Parts I and II 
Page 31 
 
Are unwilling to use barrier 
contraception methods (if 
applicable), or abstain from 
sexual intercourse, for a 
period of 3 months 
Added to clarify 
contraception not 
needed if abstain 
from sexual 
intercourse 
 
c. unsuitability for retinal 
surgery 
Added subsection 
c to list of general 
exclusions so to 
prevent subjects 
who are 
unsuitable 
candidates for 
surgery from 
enrolling 
Section 8.4 
Subjects 
Withdrawal Criteria 
Page 31 
Subjects withdrawn from the MTD 
cohort may possibly be replaced. 
 
Removed this 
sentence as this is 
no longer allowed 
Section 9.4 
Vitrectomy 
Procedure 
Pages 33-34 
To date, over 150  subjects have 
been injected 
To date, over 200 subjects 
have been injected 
Updated number 
of subjects treated 
overall with this 
type of surgical 
procedure 
If deemed easier, prior to sub-retinal 
injection of AAV8-RPGR, the 
retina will be detached 
 
Optionality 
removed because 
all surgeries are 
required to do the 
2-step BSS bleb 
Figure 2 footnote 
Page 34 
injection of BSS if necessary, an 
 
Section 9.5 
Randomisation 
Page 35 
 
Once a subject has been 
randomized, a change in 
“study eye” designation is not 
permitted.   
Added this 
requirement to 
not change study 
eye once selected 
Section 9.6 
Study Masking 
Page 35 
In Part II, all ophthalmic 
assessments that are conducted at 
the Screening/Baseline Visit will be 
conducted by appropriately 
qualified masked assessors. 
In Part II, all ophthalmic 
assessments that will be used 
as efficacy endpoints (BCVA, 
LLVA, microperimetry, 
contrast sensitivity and 
) will be conducted by 
appropriately qualified 
masked assessors (see Table 
1). 
Clarified when 
and which 
assessments must 
be masked 
 
 
 It is preferable that the same 
assessor who performed the 
Added that 
screening does 

 
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efficacy endpoint assessments 
at Screening/Baseline also 
perform the assessments 
during the masked period 
from Month 3 to Month 12. 
not need to be 
masked, but 
should if possible 
be conducted by 
same masked 
assessor as that of 
Month 3 to 
Month 12 
 
 
Table 1. Masked Assessments 
of Efficacy  
Masked Assessments at 
Month 3, 6, 9 and 12 Post-
Treatment with AAV8-RPGR 
 Best-corrected visual 
acuity 
 Low-luminance visual 
acuity 
 Microperimetry 
 Contrast sensitivity 
 25-Item Visual Function 
Questionnaire 
Table of 
assessments 
masked has been 
added 
 
 
After all Part II subjects 
complete the 3-month visit, an 
administrative IA will be 
performed by an independent 
DMC, who will review the 
accrued safety and efficacy 
data.  A small group of 
unmasked Sponsor personnel, 
who will not be involved in 
the conduct of the study 
moving forward, will have 
access to unmasked data for 
this administrative IA to 
enable regulatory interactions 
and planning for phase 3 
initiation.  
The operations team, the 
investigators, medical 
monitor, and other personnel 
who will continue to be 
involved in the daily 
operation of the study, as well 
as the subjects, will continue 
to be masked to the subjects’ 
dose level assignment and 
Description of 
maintenance of 
masking 
throughout the IA 
has been added   

 
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outcomes of the IA until study 
completion to minimise any 
operational bias.  
Furthermore, the clinical 
assessors will continue to be 
masked to the treatment 
assignment. The full details of 
masking are provided in the 
study Masking Plan. 
Section 9.8 
Concomitant 
Therapy 
Page 36-37 
Throughout the study, investigators 
may prescribe any concomitant 
medications or treatments deemed 
necessary to provide adequate 
supportive care.  Details of 
concomitant medications will be 
collected at the Screening/Baseline 
Visit and updated at every study 
visit (including the ET Visit, if 
applicable).  Concomitant 
medications (including 
prednisone/prednisolone) taken 
during the study are to be recorded 
in the subject’s medical records and 
eCRF; an exception to this is any 
medication used in the course of 
conducting a study procedure (e.g., 
anaesthesia, dilating eye drops). 
Throughout the study, 
subjects may be prescribed 
any concomitant medications, 
procedures and/ or treatments 
deemed necessary for the 
subjects’ ongoing medical 
care.  Details of medications, 
treatments and procedures 
will be collected at the 
Screening/Baseline Visit and 
updated at every study visit 
(including the ET Visit, if 
applicable).  Concomitant 
medications (including 
prednisone/prednisolone), 
treatments and procedures 
taken/undergone during the 
study are to be recorded in the 
subject’s medical records and 
eCRF; an exception to this is 
any medication used in the 
course of conducting a study 
assessment (e.g., topical 
anaesthesia, dilating eye 
drops). 
Clarified that all 
information 
regarding 
medications, 
treatments and 
procedures must 
be collected and 
not just 
medications and 
treatments 
 
In Part I, all subjects will be 
prescribed a 21-day course of oral 
prednisone/prednisolone following 
closely the 17-day protocol 
established in the Philadelphia AAV 
gene therapy clinical trial for 
treatment of patients with confirmed 
biallelic RPE65 mutation-associated 
retinal dystrophy (Maguire et al., 
2008), except allowing 
In Part I, all subjects will be 
prescribed a 21-day course of 
oral prednisone/prednisolone 
following closely the 17-day 
protocol established in the 
voretigene neparvovec-rzyl 
AAV gene therapy clinical 
trial for treatment of patients 
with confirmed biallelic 
RPE65 mutation-associated 
retinal dystrophy (Maguire et 
al., 2008), allowing… 
Added the details 
regarding the 
voretigene trial 
instead of 
referring to the 
site location 

 
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In Part II, all subjects will be 
prescribed a course of oral 
corticosteroids.  In addition, at 
the time of surgery, subjects 
(adult and pediatric) may be 
treated with up to 1 mL of 
triamcinolone,…administered 
via a deep sub-Tenon 
approach.   
Clarified that 
triamcinolone is 
optional 
Section 9.9 
Treatment 
Compliance 
Page 38 
 
The exact volume injected at 
the time of surgery should be 
recorded on the eCRF. 
Added to 
correspond with 
electronic case 
report form 
Section 10.1 
Visit 1 
(Screening/Baseline 
Period 
Page 39 
Visit 1 (Screening/Baseline Visit) 
 
Visit 1 (Screening/Baseline 
Period) 
 
Clarifies that 
Visit 1 can occur 
over more than 
one day  
 
 
The subject or parent / legal 
guardian 
Added legal 
guardian for 
minors 
 
For Part I, RPGR gene mutation 
screen (only if not conducted 
previously); for Part II, 
documentation of a non-
synonymous mutation in the RPGR 
gene  
 
 
Clarified that 
mutation screen is 
needed for both 
Parts, but can be 
done specifically 
for this study 
 
 
 
 
 
 
 
Footnotes have been re-
numbered due to re-ordering 
of list 
 
Visit 1 Footnotes 
 
1. In Part II, it is preferable 
that the same masked assessor 
who performs these 
assessments (LLVA, BCVA, 
microperimetry, contrast 
sensitivity and 
) 
during the masked period 
from Month 3 through Month 
Added footnote 
regarding 
masking 

 
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12 also perform these 
assessments at screening. 
 
 
3. Assessments at screening 
collected in triplicate.  To 
facilitate triplicate testing, the 
visit should be conducted over 
2 days. Visual field and 
microperimetry outputs will 
be sent to a CRC for review.  
Data will be generated and 
collated within the CRC and 
exported to the Sponsor or 
designee.  For 
microperimetry, the last 
assessment performed during 
screening will be used for 
assessing eligibility and will 
be defined as the baseline 
assessment. 
Clarified that the 
last 
microperimetry 
assessment will 
be considered 
baseline 
 
 
or abstain from sexual 
intercourse 
Added that 
subjects may also 
abstain from 
sexual intercourse 
in lieu of 
contraception 
 
 
Subjects may be treated at the 
time of surgery with up to 1 
mL of triamcinolone (40 
mg/mL), administered via a 
deep sub-Tenon approach. 
Clarified that 
triamcinolone is 
optional 
 
 
or abstain from sexual 
intercourse 
Added that 
subjects may also 
abstain from 
sexual intercourse 
in lieu of 
contraception 
Section 10.4 
Visit 4 
Page 42 
 
Where applicable, subjects 
will be reminded of the 
requirement to use barrier 
contraception or abstain from 
sexual intercourse for a period 
of 3 months from the time of 
treatment. 
Clarified that 
subjects should 
be reminded for 
first 3 months 
after treatment. 
Section 10.5 
Visit 5 
 
Where applicable, subjects 
will be reminded of the 
requirement to use barrier 
Clarified that 
subjects should 
be reminded for 

 
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contraception or abstain from 
sexual intercourse for a period 
of 3 months from the time of 
treatment. 
first 3 months 
after treatment. 
Section 10.6 
Visit 5.9 
Page 43 
 
Where applicable, subjects 
will be reminded of the 
requirement to use barrier 
contraception or abstain from 
sexual intercourse for a period 
of 3 months from the time of 
treatment. 
Clarified that 
subjects should 
be reminded for 
first 3 months 
after treatment. 
Section 10.7 
Visit 6 
Page 44 
Footnotes 
 
1. In Part II, at Month 3, 
LLVA, BCVA, 
microperimetry and the 
will be conducted by 
qualified masked assessors. 
Footnote added to 
clarify which 
assessments must 
be masked from 
Month 3 to 
Month 12 
Section 10.8 
Visit 7 
Page 44 
 
 
 
 
 
 
1. In Part II, at Month 3, 
LLVA, BCVA, 
microperimetry and the 
 will be conducted by 
qualified masked assessors. 
Footnote added to 
clarify which 
assessments must 
be masked from 
Month 3 to 
Month 12 
Section 10.9 
Visit 8 
Page 45 
 
1. In Part II, at Month 3, 
LLVA, BCVA, 
microperimetry and the 
 will be conducted by 
qualified masked assessors. 
Footnote added to 
clarify which 
assessments must 
be masked from 
Month 3 to 
Month 12 
Section 10.10 
Visit 9 
Page 45 
 
 
 
 
 
 
1. In Part II, at Month 3, 
LLVA, BCVA, 
microperimetry and the 
 will be conducted by 
qualified masked assessors. 
Footnote added to 
clarify which 
assessments must 
be masked from 
Month 3 to 
Month 12 

 
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Section 10.13 
Early Termination 
Visit  
Page 47-48 
 
 
 
 
 
 
 
1. In Part II, at Month 3, 
LLVA, BCVA, 
microperimetry and the 
 will be conducted by 
qualified masked assessors. 
Footnote added to 
clarify which 
assessments must 
be masked from 
Month 3 to 
Month 12 
Section 10.14 
Unscheduled Visits 
Page 48 
 
For unscheduled visits that 
occur during Part II, BCVA 
and microperimetry will be 
conducted by qualified 
masked assessors from Month 
3 through Month 12.  
 
Footnote added to 
clarify that 
assessments must 
be masked if 
unscheduled visit 
occurs from 
Month 3 to 
Month 12 
Section 11.1 
Best-Corrected 
Visual Acuity 
Page 49 
 
In Part I, at the 
Screening/Baseline Visit, eyes 
will be eligible for the study if 
they: 
Specified that 
these BCVA 
criteria were 
applicable only to 
Part I 
 
In Part II, at the 
Screening/Baseline Visit, eyes 
will be eligible for the study if 
they have a BCVA better then 
or equal to 34 ETDRS letters. 
Part II BCVA 
eligibility at 
baseline was 
clarified  
 
In Part II, it is preferable that 
the same masked assessor 
who performs the BCVA 
assessments during the 
masked period from Month 3 
through Month 12 also 
perform these assessments at 
screening. 
Although 
screening does 
not have to be 
masked, this 
statement clarifies 
that it is 
preferable that the 
same assessor 
perform 
assessments at 
baseline 
screening and 
from Month 3 to 
Month 12 
 
 
 
 
 
 
 
 

 
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Section 11.4 
MAIA 
Microperimetry 
Page 50 
 
In Part II, it is preferable that 
the same masked assessor 
who performs the 
microperimetry assessments 
during the masked period 
from Month 3 through Month 
12 also perform these 
assessments at screening. 
Although 
screening does 
not have to be 
masked, this 
statement clarifies 
that it is 
preferable that the 
same assessor 
perform 
assessments at 
baseline 
screening and 
from Month 3 to 
Month 12 
Section 11.6 
Contrast 
Sensitivitity 
Page 51 
 
In Part II, it is preferable that 
the same masked assessor 
who performs the contrast 
sensitivity assessments during 
the masked period from 
Month 3 through Month 12 
also perform these 
assessments at screening. 
Although 
screening does 
not have to be 
masked, this 
statement clarifies 
that it is 
preferable that the 
same assessor 
perform 
assessments at 
baseline 
screening and 
from Month 3 to 
Month 12 
Section 11.7 
Low-luminance 
Visual Acuity 
Page 51 
 
In Part II, it is preferable that 
the same masked assessor 
who performs the LLVA 
assessments during the 
masked period from Month 3 
through Month 12 also 
perform these assessments at 
screening. 
Although 
screening does 
not have to be 
masked, this 
statement clarifies 
that it is 
preferable that the 
same assessor 

 
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perform 
assessments at 
baseline 
screening and 
from Month 3 to 
Month 12 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Section 12 
Throughout 
medication 
drug 
In all the AE 
definitions 
section, the word 
‘medication’ has 
been changed to 
‘drug’ to align 
with all protocols  
Section 12.2.1.2 
Serious Adverse 
Event 
Page 53 
Hospitalisation for a pre-existing 
condition, including elective 
procedures, which has not 
worsened, does not constitute an 
SAE. 
Hospitalisation that was pre-
scheduled or for an elective 
procedure or routinely 
scheduled treatment for a pre-
existing condition, which has 
not worsened, does not 
constitute an SAE. 
Clarified the 
types of 
hospitalization 
that would be 
defined as SAEs; 
made consistent 
template language 
across studies ad 
protocols 
Section 12.2.1.2 
Serious Adverse 
Event 
Page 54 
The following vision loss or vision-
threatening events are to be reported 
as SAEs: 
• 
Sustained decrease in VA 
of ≥15 letters on ETDRS chart 
compared to baseline, except for 
surgery-related events. 
Sustained is defined as lasting 48 
hours or more until recovery; 
Vision Loss to Be Reported as 
a Serious Adverse Event 
Vision Loss NOT TO BE 
Reported as an SAE: 
• 
Surgery-related 
BCVA decrease of ≥15 letters 
on ETDRS chart occurring 
within 1 day of surgery, but 
recovering / resolving at post-
operative Days 7 and 14.  
Clarified 
definitions for 
vision loss 
reporting as SAE 

 
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recovery defined as VA returned to 
within 5 letters of baseline VA. 
Surgery-related events of VA 
decrease are defined as VA 
decreases occurring in close 
temporal association (within <24 
hours) with the surgical 
administration of the study 
medication, and which are resolving 
at Day 7 (Visit 4) post-surgery.  
These events are not to be reported 
as an AE or SAE.  However, they 
should be reported as an AE if in the 
investigator's opinion, their 
evolution in terms of duration or 
severity cannot be explained by the 
procedure.  This would include, but 
not be limited to instances where the 
abnormal course of post-surgery VA 
decrease is associated with another 
complication attributable to the 
surgery or the study medication, or 
where the abnormal course of post-
surgery VA decrease can be 
attributed to another identifiable 
cause. 
• 
AEs that in the opinion of 
the investigator, actually or 
potentially require any surgical or 
medical intervention to prevent 
permanent loss of sight. 
Vision Loss or Vision-
Threatening Event TO BE 
Reported as an SAE: 
• 
Surgery-related 
BCVA decrease of ≥15 letters 
on ETDRS chart that occurs 
within 1 day of surgery and 
that has not recovered* by the 
1-Month Visit. 
• 
A decrease in BCVA 
of ≥15 letters on ETDRS 
chart that occurs within 1 day 
of surgery, however, in the 
investigator’s opinion: 
o 
Has an evolution not 
consistent with the expected 
post-operative course;  
o 
May be attributable 
to a complication that 
occurred during surgery, or 
another untoward event, or 
the study drug;  
o 
Actually or 
potentially requires any 
surgical or medical 
intervention to prevent 
permanent loss of vision. 
• 
Non-surgery-related, 
sustained (>48 hours 
duration) decrease from 
baseline in BCVA of ≥15 
letters on ETDRS chart. 
*Recovery / Resolution of 
BCVA loss is defined as a 
return to within 10 letters of 
the baseline BCVA on the 
ETDRS chart. 
Section 12.2.2 
Recording of 
Adverse Events 
Page 54 
 
/ legal guardian 
Added legal 
guardian for 
minors 
 
AE severity and relationship 
to the study drug or the 
surgical procedure will be 
assessed at the site by the 
investigator or a medically 
qualified designee. 
Updated text for 
time points, 
evaluation and 
definition of AE 
severity and 
relationship; 

 
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clarified and 
updated to be 
consistent across 
all studies and 
protocols 
 
AE Severity… 
 
AE Relationship 
 
Unrelated:  
is not 
reasonably related in time to 
the administration of the study 
drug/surgical procedure, or 
exposure of the study 
drug/surgical procedure has 
not yet occurred, or biologic 
plausibility does not exist 
Related:  A reasonable 
possibility exists that the 
study drug / study procedure 
caused the AE. A suspected 
AE can be further defined 
by:… 
 
 
Definitely related: There is a 
causal …. 
When a relationship is 
determined to exist, the 
investigator or medical 
designee will further define if 
that relationship is to the 
study drug, the surgical 
procedure, both, or unknown. 
Updated text for 
time points, 
evaluation and 
definition of AE 
severity and 
relationship 
 
Definitions of AE 
relationship are 
now binary 
(related / 
unrelated) with 3 
possibilities of 
relatedness as a 
subcategorization. 
This eliminates 
the ‘unlikely to be 
related’ which is 
subject to error 
Section 12.2.3 
Follow-up of 
Adverse Events 
Page 56 
 
/ legal guardian 
Legal guardian 
added for minors 
 
 
Investigators are expected to 
timely provide the requested 
additional information for a 
complete assessment and 
documentation of the SAE 
reports in a timely manner. 
Added 
clarification  

 
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Section 12.2.4 
Reporting of 
Serious Adverse 
Events and Dose-
Limiting Toxicities 
Page 56-57 
emailing a DLT/SAE form to 
   
emailing the DLT/SAE form.  
For reporting purposes, the 
date of SAE form submission 
by the investigator to the 
Sponsor will be designated as 
Day 0.   
Clarified the 
procedure and 
timing of SAE 
reporting. 
 
 
Follow-up SAE reports will 
be submitted within 15 days 
of receiving the information. 
Clarified the 
procedure and 
timing of SAE 
reporting. 
Section 12.2.6 Data 
Monitoring 
Committee 
Page 57 
 
For Part I, an independent 
DMC 
Clarified that the 
fist paragraph 
described the 
safety monitoring 
responsibilities of 
the Part I DNC 
only 
 
After all Part II subjects 
complete the 3-month visit, an 
administrative IA will be 
performed by an independent 
DMC, who will review the 
accrued safety and efficacy 
data.  A small group of 
unmasked Sponsor personnel, 
who will not be involved in 
the conduct of the study 
moving forward, will have 
access to unmasked data for 
this administrative IA to 
enable regulatory interactions 
and planning for phase 3 
initiation.  
Following the administrative 
IA, the DMC will continue to 
meet, as described in the 
DMC Charter. 
Defined the 
activities of the 
Part II DMC  
Section 12.3 
Pregnancy 
Page 57 
the investigator shall immediately 
(within 24 hours of learning of the 
event) report the pregnancy, with at 
least preliminary data, to the 
Sponsor (or its designee) by 
completing and emailing a 
Pregnancy Notification Form to 
In 
addition, if possible, outcome of the 
Consent from the pregnant 
partner is required prior to the 
collection of personal data. 
However, … 
 
the investigator shall 
immediately (within 24 hours 
of learning of the event) 
Clarified that 
informed consent 
must first be 
obtained before 
collecting 
information from 
a potential 
pregnant partner 

 
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pregnancy fathered by the subject 
should be recorded and followed up 
until delivery for, congenital 
abnormality or birth defects. 
report the pregnancy, with at 
least preliminary data,… 
 
In addition, if possible, 
outcome of the pregnancy 
fathered by the subject should 
be recorded including any 
congenital abnormality or 
birth defects. 
 
 
Section 12.7.3 
Immunogenicity 
Testing 
Page 59 
 
Enzyme-linked immunospot 
(ELISPOT) assays will be 
used…. and cell-based 
methods. 
Clarified the 
methodology and 
storage of 
samples for 
immunogeniciity 
All immunogenicity samples will be 
sent to and stored at a central 
laboratory laboratories for future 
analyses. 
All immunogenicity samples 
will be sent to central 
laboratories for analyses. 
 
Residual samples may be 
stored for up to 15 years or 
per local regulations. 
Section 13.3.1 
Safety Analysis Set 
Page 60 
The Safety Analysis Set will consist 
of all subjects who receive study 
treatment (vitrectomy/AAV8-
RPGR) in Part I, and all subjects 
that are randomized in Part II.   
For Part I, the Safety Analysis 
Set will consist of all subjects 
who receive study treatment 
(vitrectomy/AAV8-RPGR).   
Clarified that all 
subjects treated 
under 2-arm and 
3-arm 
randomization 
schedules will be 
included in the 
Safety Analysis 
Set. This accounts 
for any subjects 
enrolled and 
treated under 
previous versions 
of the protocol.  
 
For Part II, the Safety 
Analysis Set will consist of all 
subjects who are randomised, 
under both the 2- and the 3-
arm randomisation schedules.  
The Safety Analysis Set will 
be the primary population for 
demographics, baseline 
characteristics and safety 
analyses.  Subjects will be 
analysed based on the actual 
treatment received. 
Section 13.3.2 
Intent-to-Treat 
(ITT) Analysis Set 
Page 60 
The Full Analysis Set will include 
all subjects for whom data of at 
least 1 post baseline efficacy 
assessment is available in the study 
The intent-to-treat (ITT) 
Analysis Set will consist of all 
Part II subjects who are 
randomised, under the 3-arm 
randomisation schedules.  The 
ITT Analysis Set will be used 
The ITT set is 
now clarified to 
include only 
subjects treated 
under the 3-arm 
randomization 

 
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eye.  The Full Analysis Set will be 
used for efficacy analyses. 
for the efficacy analyses.  
Subjects will be analysed 
based on the treatment to 
which they were randomised. 
The modified intent-to-treat 
(mITT) Analysis Set will 
include all Part II subjects 
who are randomised under the 
3-arm randomisation schedule 
and who receive study 
treatment (or the phone call 
for those in the untreated 
control group) and who have 
baseline microperimetry data 
and at least 1 post-baseline 
microperimetry data in the 
study eye.  The mITT 
Analysis Set will be used for 
supportive and sensitivity 
analysis for Part II primary 
and secondary efficacy 
endpoints.  Subjects will be 
analysed based on the 
treatment to which they were 
randomised. 
schedule. It also 
clarifies that the 
true definition of 
ITT will be used 
for the primary 
endpoint analysis.  
The modified ITT 
set will be used to 
analyse the 
primary and 
secondary 
endpoints in 
sensitivity and 
supportive 
analysis because 
some subjects 
might be 
randomized and 
not treated.  
Section 13.6 
Efficacy Analyses 
 
The proportion of eyes with 
improved retinal sensitivity, 
for both the center grid (i.e., 
the central 16 loci) and the 
entire grid (i.e., all 68 loci), 
will be compared between 
study arms (high dose vs 
untreated; low dose vs 
untreated) using the Fisher 
Exact-Boschloo test with a 
Berger-Boos correction of 
beta=0.001 (Berger 1994).  In 
addition, the difference in 
proportions between study 
arms will be presented with 
its corresponding 95% CI 
calculated using the method 
of Miettinen and Nurminen 
(Miettinen 1985).  
Change from baseline in mean 
sensitivity, in both the center 
grid and the entire grid, will 
be compared between study 
The Statistical 
Analysis Plan has 
since been 
finalized and 
therefore further 
details on the 
statistical 
analyses have 
been added to the 
protocol 

 
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arms using an ANCOVA 
model including baseline 
value and study arm (high 
dose, low-dose, and 
untreated) as covariates.  The 
difference in means between 
study arms, and its 95% CI, 
will be derived from the same 
ANCOVA model. 
Section 13.6.1 
Multiplicity 
Adjustment 
Page 61 
 
In Part II, an administrative 
IA is included to facilitate the 
planning of Phase 3 activities.  
As no early stopping for 
efficacy is allowed, no 
multiplicity adjustment is 
required for the administrative 
IA.  The final analysis will be 
conducted at 0.05 two-sided 
level for the primary 
endpoint. 
It is clarified that 
multiplicity 
adjustment is not 
needed in 
conducting the 
administrative IA 
because no early 
stopping for 
efficacy is 
allowed.  
Section 13.8 
Interim Analysis 
Page 62 
 
In Part II, after all subjects 
complete the 3-month visit, an 
administrative IA will be 
performed by an independent 
DMC.  The DMC will review 
the accrued safety and 
efficacy data.  A small group 
of unmasked Sponsor 
personnel, who will not be 
involved in the conduct of the 
study moving forward, will 
have access to unmasked data 
for this administrative IA to 
enable regulatory interactions 
and planning for phase 3 
initiation.   
The details of the roles and 
responsibilities of the Part II 
DMC are provided in the 
DMC charter, and the full 
details of masking are 
provided in the study Masking 
Plan.  
The study will continue as 
planned.  A final analysis will 
be conducted at the end of the 
study, i.e., after all subjects 
Details of the 
administrative IA 
are included for 
Part II.  

 
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complete the study.  The end 
of the study is defined as the 
date the last subject completes 
his final-visit assessments (or 
early termination [ET] 
assessments in the event of 
premature discontinuation) or 
the date of last data collection 
if the last subject is lost to 
follow-up. 
Section 14.1 
Informed Consent 
Page 64 
 
/legal guardian 
Legal guardian 
language is 
included 
throughout in the 
case of minors 
 
In the case of a female partner 
pregnancy fathered by a 
subject, a partner pregnancy 
informed consent form must 
be signed and dated before 
collecting information 
regarding the outcome of the 
pregnancy (birth or 
spontaneous abortion), as well 
as any incidents of congenital 
abnormality, birth defect or 
other medical problems. 
The requirement 
for pregnant 
partner informed 
consent prior to 
obtaining any 
information is 
included 
Section 14.2 
Ethical/Regulatory 
Review 
Page 64 
 
, in accordance with local 
requirements, 
Clarified that 
submission is 
necessary in 
accordance with 
local 
requirements only 
Section 14.3 
Regulatory 
Considerations 
Page 65 
 
The study will be conducted 
in accordance with the 
relevant articles of the 
Declaration of Helsinki, 
where permissible. 
In some regions, 
the Declaration of 
Helsinki cannot 
be adhered to. 
Section 15.2 
Data Handling and 
Records 
Management 
Page 66 
 
All study data will be entered 
on an encrypted EDC system 
with individual pass-codes 
known to all each 
investigators 
Clarified the 
process of data 
handling 

 
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Two reading centres are anticipated.    
Removed 
unnecessary 
detail 
Section 16 
References 
Page 68 
 
Berger R.L., Boos D.D. P 
values maximized over a 
confidence set for the 
nuisance parameter. Journal 
of the American Statistical 
Association 1994; 89: 1012-
1016 
Miettinen, O. S. and 
Nurminen, M. ‘Comparative 
analysis of two rates’, 
Statistics in Medicine, 4, 213-
226 (1985). 
Added reference 
related to the 
statistical tests 
used 
Table 3 
Page 73-76 
 
 
 
 
 
Reordered al footnote 
numbering 
 
Footnote l 
 
The final microperimetry 
assessment will be used to 
determine eligibility. 
Added a 
clarification on 
microperimetry 
that the final 
assessment 
should be used 
for baseline to 
determine 
eligibility 
Throughout 
Protocol 
 
 
Changed Years to 
months post-
treatment for 
consistency 

 
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A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene Therapy for X-
linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) Encoding Retinitis 
Pigmentosa GTPase Regulator (RPGR) 
Version 10.0 
Summary of Changes 
10 October 2019 
All Headers 
Version 9 
14 Aug 2019 
Version 10.0 
10 Oct 2019 
Upversion and 
date change, 
throughout 
document 
Title Page 
 
Version 10.0 
10 Oct 2019 
Added version 
and date to list of 
amendments 
Sponsor Approval 
Page, 3 
 
Version 10.0 
10 Oct 2019 
Added version 
and date to list of 
amendments 
Investigator’s 
Signature Page 
Page 4 
 
Version 10.0 
10 Oct 2019 
Added version 
and date to list of 
amendments 
Section 10.1 Visit 1 
(Screening/Baseline 
Period)  
Page 38 
The next study visit (Visit 2) is to be 
scheduled within 8 weeks of the 
Screening/Baseline Visit. 
The next study visit (Visit 2) 
is to be scheduled within 12 
weeks of the 
Screening/Baseline Visit. 
Window changed 
from 8 to 12 
weeks between 
screening and 
surgery to 
provide increased 
operational 
flexibility and 
decrease patient 
burden 
Table 3, Schedule 
of Study 
Procedures, 
Footnote a, Page 72 
The Screening/Baseline Visit must 
be performed within 8 weeks of 
Visit 2  
The Screening/Baseline Visit 
must be performed within 
12 weeks of Visit 2  
See above 
 

AAV8-RPGR 
 
Version 6 to Version 8 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 DEC 2018 
 
CONFIDENTIAL 
Page 1 of 44 
 
SUMMARY OF CHANGES FOR CLINICAL STUDY PROTOCOL  
NSR-RPGR-01  
Version 6.0 to Version 8.0 
 
AAV8-RPGR 
 
A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa GTPase Regulator (RPGR) 
Indication: 
X-Linked Retinitis Pigmentosa 
Study Phase: 
1/2/3 
Sponsor: 
NightstaRx Ltd 
2nd Floor 
10 Midford Place 
London W1T 5BJ, UK 
Telephone:  +44 (0) 020 7062 2777 
Summary of Changes: 
Protocol Version 6.0 to 8.0 
18 DEC 2018 
CONFIDENTIALITY STATEMENT 
This protocol is the property of NightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. 
Persons to whom the information is disclosed must be informed that the information is 
CONFIDENTIAL and may not be further disclosed by them. 
 
 

AAV8-RPGR 
 
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Summary of Changes: Protocol: NSR-RPGR-01 
 
18 DEC 2018 
 
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Overview / Rationale: Changes to the Part II Dose-Expansion Phase of the Study 
From NSR-RPGR-01 Version 6.0 to 7.0, the protocol amendment changes the doses to be 
expanded in Part II from the “MTD and 3-dose levels lower than MTD” to dose 3 and dose 5. 
Rationale for this change was provided by the DMC at the October 2018 meeting. Although no 
DLTs have been identified through cohort 6 treated with the highest dose, and therefore a true 
MTD has not been identified in this dose-escalation, the committee recommended to expand 
dose 5 and dose 3, as the doses most likely to define safety and efficacy of AAV8-RPGR. In 
addition, regulatory agencies have recommended adding a third untreated arm to better establish 
efficacy and safety of the gene therapy.  Thus, the subjects will be randomized in a 1:1:1 
allocation, with double masking to dose in the treated arms, and masked assessments of efficacy. 
The study duration has been shortened to 12 months of follow-up for Part II dose-expansion 
because a long-term follow-up study will be initiated to continue follow-up of all AAV8-RPGR 
subjects from 12 months to out to 5 years. Phase 1 subjects will still be followed for 24 months, 
and then also invited to participate in the long-term study.  
The endpoints and inclusion criteria are now separated by study Part to improve clarity.  
An efficacy endpoint, microperimetry at 3 months, has been added to Part II based on early 
efficacy signals observed during dose-escalation. Related to this, an inclusion range for 
microperimetry has been added to Part II in order to assure the inclusion of subjects with 
modifiable disease and to avoid inclusion of those with microperimetry values subject to ceiling 
effects.   
Additionally, to further our understanding of the effects of AAV8-RPGR, assessments of 
, 
 
 and quality of life questionnaires have been added, the former two only in sites with 
the available technology. Some assessments (reading test, color vision, and full-field threshold 
sensitivity [FST]) have been removed from the study assessments due to the excessive burden of 
study visits on the subjects, and the limited value of these assessments in understanding both the 
disease and the effects of the drug.  
To improve safety and to prevent potential inflammatory response to therapy, the steroid regimen 
has been modified.  A standardized adult starting dose of 60 mg has been selected (rather than 
the previous 1mg/kg starting dose) and the taper has been lengthened to include coverage out to 
approximately 2 months. A 2-month visit has been added to assess the subjects at the end of the 
steroid therapy.  
Information on the procedures related to unmasking has been added to comply with Good 
Clinical practices. Serious adverse event reporting has also been changed to immediately instead 
of within 7 days, per regional recommendations. 
From NSR-RPGR Version 7.0 to Version 7.1, this administrative protocol amendment clarifies 
the procedures and requirements for assessments done at each visit compared to the Schedule of 
Study Procedures.  Footnotes for BCVA assessment, Immunogenicity sampling, and 
corticosteroid review were added to the in-text footnotes and Schedule of Study Procedures.  In 
addition, Fundus photography was removed from Visit 6 and Visit 7, viral shedding was 
removed from Visit 6, and autofluorescence assessment was added to the Unscheduled Visit.  
Updates were made to the protocol to accommodate these changes. 

AAV8-RPGR 
 
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CONFIDENTIAL 
Page 4 of 44 
 
Page numbers on the following table of changes refer to the tracked changes version of the 
protocol amendment. 
From Version 7.1 to Version 8.0, the unmasking information has been modified in Section 12.2.5 
to adhere more closely to Good Clinical Practices. Also, the mobility test has been added to the 
Early termination Visit list of procedures, to be conducted if feasible.  
Updates noted in italics are those referring to Version 7.0 to Version 7.1.  
Updates noted in italics and bold, with grey shading, are those referring to Version 7.1 to 
Version 8.0. 
 

AAV8-RPGR 
 
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SUMMARY OF CHANGES  
PROTOCOL NSR-RPGR-01  
Version 8.0, 18 DEC 2018 
Section, Page 
Previous Text  
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Rationale 
Title Page 
A Dose Escalation, 
Phase 1/2 Clinical Trial 
of Retinal Gene Therapy 
for X-linked Retinitis 
Pigmentosa Using an 
Adeno-Associated Viral 
Vector (AAV8) Encoding 
Retinitis Pigmentosa 
GTPase Regulator 
(RPGR) 
A Dose Escalation (Phase 1), and 
Dose-Expansion (Phase 2/3) 
Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis 
Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
Added to title the 
dose-expansion and 
phase of the study 
has been specified 
for dose escalation 
to be Phase 1 and 
for dose expansion, 
to be Phase 2/3 
Title Page, 
Header 
 
Version 7.1 
07 Dec 
Updated Header 
Title Page, 
Header 
 
Version 8.0 
18 Dec 2018 
Updated Header 
Title Page, 
Pages 1, 5, 6, 22 
 
STUDY PHASE  1/2/3 
Added Phase 3 to 
Study Phase 
Title Page, 
Original Protocol 
Date 
 
VERSION 7.1 
07 Dec 2018 
Added Version 7.1 
Title Page, 
Original Protocol 
Date 
 
VERSION 8.0 18 Dec 2018 
Added Version 8.0 
Sponsor.   
Page 1 
Wellcome Gibbs 
Building, 215 Euston 
Road 
London NW1 2BE, UK 
207 611 2077 
 
2nd Floor 
10 Midford Place 
London W1T 5BJ UK 
020 7062 2777 
Change of address 
and telephone 
Sponsor Approval.   
Page 2 
 
 
, MD 
 
 
Personnel change 
16 Nov 
07 Dec 
Updated date for 
version 7.1 
 
18 Dec 2018 
Updated date for 
version 8.0 
Investigator’s 
Signature Page 
16 Nov 
07 Dec 
Updated date for 
version 7.1 
 
 
18 Dec 2018 
Updated date for 
version 8.0 
Contact 
Information.  
Pages 4 
 
Rx Ltdr 
Wellcome Gibbs Building, 
Euston Road 
London NW1 2BE, UK 
+44 (0) 207 611 2034 
 
The contact page 
within the protocol 
now includes only 
the 
pharmacovigilance 
contact and the 
responsible CRO. 
The complete study 
 
 

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NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
+44 (0) 207 611 2193 
contact list will be 
included in the 
study manual. 
The safety email 
remains the same 
and is listed. 
, MD 
NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
 
Email: 
 
+1-919-401-8003 
Change in 
personnel and 
contact information 
Contract Research 
Organization 
 
 UK 
 
 
 
 
 
 
 UK 
 
New address and 
phone  
 
 
NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
781-457-+44 (0) 207 611 
2271 
 
The contact sheet 
within the protocol 
now includes only 
the 
pharmacovigilance 
contact and the 
responsible CRO. 
The complete study 
contact list will be 
included in the 
study manual. 
The safety email 
remains the same 
and is listed. 
81 Hatrwell Avenue,  
Suite 100 
Lexington, MA 02421 
  
Synopsis 
Study Period 
(years) 
Page 5 
36 months 
Part I: 24 months 
Part II: 12 months 
Duration of study 
corrected from 
estimate last 
patient, last visit to 
actual duration for 
each subject in Part 
I 
Synopsis 
Inclusion Criteria  
Page 8 
Prior documentation… 
Documentation 
Clarified 
documentation 
requirement 
Synopsis   
Endpoints 
Page 5 
The primary safety 
endpoint is incidence of 
dose-limiting toxicities 
(DLTs) and treatment-
emergent adverse events 
Endpoints 
Part I 
Primary Endpoints:  
The primary safety endpoints are the 
incidence of dose-limiting toxicities 
(DLTs), and treatment-emergent 
Separated out Part I 

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(TEAEs) over a 24-month 
period. 
adverse events (TEAEs) over a 24-
month period.   
Secondary and Exploratory 
Endpoints: 
• Change from baseline in 
microperimetry at 3, 6, 12, 18 and 
24 months 
• Change from baseline in best-
corrected visual acuity (BCVA) at 
3, 6, 12, 18, and 24 months 
• Change from baseline in spectral 
domain optical coherence 
tomography (SD-OCT) at 3, 6,12, 
18 and 24 months 
• Change from baseline in 
autofluorescence at 3, 6, 12, 18 
and 24 months 
• Change from baseline in other 
anatomical and functional 
outcomes at 3, 6, 12 months, 18 
and 24 months 
Synopsis.   
Endpoints 
Pages 5-6 
 
Part II 
Primary Efficacy Endpoint: 
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
Safety Endpoint: 
The safety endpoint is incidence of 
TEAEs over a 12-month period. 
Separated out Part 
II  
Synopsis.   
Endpoints 
Pages 5-6 
• Change from baseline 
in microperimetry at 3, 
6, 9, 12 18 and 24 
months 
• Change from baseline 
in best-corrected visual 
acuity (BCVA) at 3, 6, 
12 18 and 24 months 
• Change from baseline 
in SD-OCT at 3, 6, 12 
18 and 24 months 
• Change from baseline 
in autofluorescence at 
3, 6, 12, 18 and 24 
months 
Secondary Endpoints: 
• 
Change from baseline in 
microperimetry at 1, 6, 9, and 
12 months 
• 
Change from baseline in best-
corrected visual acuity (BCVA) 
at 3, 6, and 12 months 
• 
Change from baseline in SD-
OCT at 3, 6, and 12 months 
• 
Change from baseline in 
autofluorescence at 3, 6, and 12 
months 
• 
Change from baseline in visual 
field assessed by Octopus 900 
at 3, 6, and 12 months 
Updated Part II 
endpoints 
• 
Change from baseline 
in other anatomical 
Exploratory Endpoints: 
 
• Updated Part II 
endpoints 

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Rationale 
and functional 
outcomes at 3, 6, 12, 
18 and 24 months 
• 
 
• 
 
• 
 
 
• 
 
 
Synopsis.   
Study Design  
Pages 6-7 
The study will be 
conducted in two parts: 
Part I is a dose escalation 
study, Part II is a 
Maximum Tolerated Dose 
(MTD) expansion study 
(as determined in Part I) 
This is a Phase 1/2/3… 
Part I is a dose-selection study; Part 
II is a dose-expansion study, with 2 
doses (2.5 × 10^11 gp [high dose], 5 
× 10^10 gp [low dose]) selected 
from Part I based on a benefit/risk 
assessment, and a third untreated 
group to allow for a controlled 
comparison of efficacy and safety.   
Study design 
description updated 
to include Part I 
and Part II. Part II 
now defines doses 
as high and low 
doses and not as 
MTD since the 
chosen high dose to 
be expanded has 
not been defined as 
MTD. 
The study will consist 
of visits over a 24-month 
evaluation period. 
 
At the 
Screening/Baseline Visit, 
each subject will be 
assessed for eligibility of 
both eyes. Only 1 eye 
will receive treatment 
(the “study eye”), and the 
untreated eye will be 
designated as the “fellow 
eye”.   
Part I consists of 12 visits over a 24-
month evaluation period. 
 
Part II consists of 10 visits over a 
12-month evaluation period. Only 1 
eye will be randomized (the “study 
eye”), and the other eye will be 
designated as the “fellow eye”.  
Selection of the “study eye” will be 
made on clinical grounds prior to 
randomization and will generally be 
the worse eye affected. 
Differentiates the 
visit number and 
duration for Parts I 
and II 
 
Subjects in the untreated control 
group will receive study-visit 
telephone calls to monitor 
AEs/SAEs and review concomitant 
medications on Visit 2 (Day 0) and 
on Visits 3 and 4 (post-operative 
Days 1 and 7). 
Information on 
conduct for 
untreated control 
subjects has been 
added regarding the 
surgery day and 
post-operative 
Days 1 and 7.  
To minimise 
inflammation resulting 
To minimise inflammation resulting 
from surgery and/or 
To improve safety 
and to prevent 

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from surgery and/or 
vector/transgene, all 
subjects will be given a 
21-day course of oral 
corticosteroid (e.g., 
prednisolone/prednisone) 
that will start 2 days 
before the planned date 
of surgery. 
vector/transgene, in Part I, all 
subjects will be given a 21-day 
course of oral corticosteroid (e.g., 
prednisolone/prednisone) that will 
start 2 days before the planned date 
of surgery. 
In Part II, all subjects will be treated 
at the time of surgery with up to 1 
mL of triamcinolone (40 mg/mL), 
placed behind the globe via a deep 
sub-Tenon approach.  All subjects 
will also be given a 9-week course 
of oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, 
followed by 6 weeks of tapering 
doses. The dose regimen is adjusted 
for pediatric subjects treated in Part 
II (see Section 9.8).   
potential 
inflammatory 
response to 
therapy, the steroid 
regimen has been 
modified.  A 
standardized adult 
starting dose of 60 
mg has been 
selected (rather 
than the previous 
1mg/kg starting 
dose) and the taper 
has been 
lengthened to 
include coverage 
out to 
approximately 2 
months. A 2-month 
visit has been 
added to assess the 
subjects at the end 
of the steroid 
therapy. 
 
At study completion, Part I subjects 
will be invited to participate in a 
separate long-term follow-up study 
that will collect efficacy and safety 
data up to 5 years from surgery. 
Added the 
extension of 
follow-up for Part I 
subjects 
Part II: MTD Expansion 
Study 
 
Part II: Dose Expansion  
In Part II, 45 subjects will be 
randomized 1:1:1 to a high-dose 
(2.5 × 10^11 gp), a low-dose 
(5 × 10^10 gp), and a third untreated 
group to allow for a controlled 
comparison of efficacy and safety. 
Study data will be collected for both 
eyes of each subject. Since treatment 
requires an invasive surgical 
procedure under general anaesthesia, 
the sponsor, investigator and the 
subject will be unmasked to the 
study procedure (i.e., vitrectomy and 
sub-retinal injection), however 
within the treated groups, the 
sponsor, investigator and subject 
will be masked to the assigned dose. 
To further minimise potential bias of 
the treated and non-treated eye 
evaluations, all subjective 
Clarified 
randomization for 
Part II Dose 
Expansion as 3-
armed study with 
untreated arm 
added, per general 
rationale above.  
Added language 
explaining the 
assessor masking. 

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SUMMARY OF CHANGES  
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ophthalmic assessments at the 
Screening/Baseline Visit (Visit 1) 
and from Month 1 (Visit 5) onwards 
will be conducted by a masked 
assessor. 
Once the MTD has been 
identified, up to 45 
additional subjects will be 
randomized, in a 2:1 
allocation ratio.  Subjects 
will receive AAV8-RPGR 
either at the MTD (MTD 
cohort), or at a low dose 
(active-control cohort), 
three dose-levels below 
the MTD (e.g., low dose = 
5 x 1010 gp if MTD = 
5x1011 gp).  Part II of the 
study will be randomized 
and double-masked to the 
assigned dose, and open-
label to the treatment 
administration. 
Subjects, sponsor, investigators and 
clinical assessors will be masked to 
the assigned dose.   
All Part II subjects will be followed 
for 12 months with the pre-specified 
visit schedule.  At study completion, 
Part II subjects will be invited to 
participate in a separate long-term 
follow-up study that will collect 
efficacy and safety data from Month 
12 through 5 years from surgery. 
Clarified 
randomization for 
Part II Dose 
Expansion as 3-
armed study with 
untreated arm 
added, per general 
rationale above. 
Synopsis 
Inclusion Criteria  
Page 7 
1. Subject / parent (if 
applicable) is willing 
and able to give 
informed consent for 
participation in the 
study 
 
Part I is only in 
adults so removed 
the language for 
minors 
Synopsis  
Inclusion Criteria 
Page 7 
2. Are male and able to 
comply and adequately 
perform all study 
assessments 
Part I:≥18 years of age 
Part II: ≥10 years of age 
Part I 
Are male, ≥18 years of age, and able 
to comply and adequately perform 
all study assessments. 
Clarified age 
inclusion criterion 
for Part I;  
separated Part I and 
Part II inclusion 
criteria to add 
clarity for 
investigators; 
Synopsis 
Inclusion Criteria 
Page 7 
5. BCVA in both eyes that 
meets the following 
criteria, based on the 
cohort level: 
Cohort 4-6 and study 
Part II: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better 
than or equal to 6/60 
or 20/200 Snellen 
acuity) 
5. BCVA in both eyes that meets the 
following criteria, based on the 
cohort level: 
Cohort 4-6: better than or 
equal to BCVA of 34 
ETDRS letters (equivalent 
to better than or equal to 
6/60 or 20/200 Snellen 
acuity) 
Removed Part II 
BCVA inclusion 
criterion because 
inclusion criteria 
are now 
separated for Part 
II to improve 
clarity 

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Rationale 
 
Synopsis 
Inclusion Criteria 
Part II 
Pages 8 
 
Part II 
Inclusion Criteria 
1. Subject / parent (if applicable) is 
willing and able to provide informed 
consent for participation in the study 
2. Are male, ≥10 years of age, and 
able to comply and adequately 
perform all study assessments 
3. Documentation of a non-
synonymous mutation in the RPGR 
gene 
4. Have active disease clinically 
visible within the macular region in 
the study eye and defined as follows: 
 ellipsoid zone (EZ) on SD-OCT at 
screening must be measurable, and 
within the nasal and temporal 
border of any B-scan, and not be 
visible on the most inferior and 
superior B-scan 
5.Have a BCVA in the study eye 
that meets the following criteria: 
•Better than or equal to BCVA of 34 
ETDRS letters (equivalent to better 
than or equal to 6/60 or 20/200 
Snellen acuity). 
6. Mean total retinal sensitivity in 
the study eye as assessed by 
microperimetry ≥0.1 dB and ≤8 dB  
• Added section for 
Part II inclusion 
criteria to clarify 
the differences 
between Parts I 
and II; 
• EZ zone must be 
measurable on 
screening in the 
study eye 
• BCVA is same for 
all subjects in Part 
II (no cohort 
differences); 
specifies criterion 
is for study eye 
only 
• Added mean total 
retinal sensitivity 
range in the study 
eye to ensure that 
subjects have 
modifiable 
microperimetry 
not subject to 
ceiling effects 
Synopsis, 
Exclusion Criteria 
Page 9 
 
Exclusion Criteria: Parts I and II 
Specifies that 
exclusion criteria 
are the same for 
both parts 
Synopsis 
Test Product, 
Dosage, and Mode 
of Administration 
Page 9 
 
Part I, Dose Escalation, Phase 1: 
All subjects will undergo vitrectomy 
and receive a single sub-retinal 
injection of AAV8-RPGR. Subjects 
will be assigned to 1 of the 
following AAV8-RPGR dose levels: 
5 × 10^9 gp, 1 × 10^10 gp, 
5 × 10^10 gp, 1 × 10^11 gp, 
2.5 × 10^11 gp, or 5 × 10^11 gp. 
 
Part II, Dose Expansion, Phase 2/3: 
Subjects will be assigned to 1 of the 
following: high-dose 
(2.5 × 10^11 gp), low-dose 
(5 × 10^10 gp), or an untreated 
control arm. 
Separated out Parts 
I and II for 
improved clarity 

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Synopsis.   
Reference Therapy 
Page 10 
In Part I, no Reference 
therapies will be 
administered. In Part II, a 
high dose and a low dose 
of AAV8-RPGR (active-
control cohort) the 
concentration of which 
will be three  dose-levels 
from MTD. 
In Part I, no Reference therapies will 
be administered. In Part II, 2 doses 
of AAV8-RPGR will be compared: a 
high-dose (2.5 × 10^11 gp) and a 
low-dose (5 × 10^10 gp).  An 
untreated control arm will also be 
added. 
Added comparator 
dosing and 
untreated arm to 
reference therapy 
Synopsis.   
Criteria for 
Evaluation 
Page 10 
Efficacy: The efficacy 
evaluation will be based 
on BCVA, SD-OCT, 
fundus autofluorescence, 
visual fields, 
microperimetry, contrast 
sensitivity, low luminance 
VA, full field stimulus 
threshold test, colour 
vision and reading test. 
Efficacy: The efficacy evaluation 
will be based on microperimetry 
(MAIA), BCVA, SD-OCT, 
, fundus 
autofluorescence, visual fields 
(Octopus 900 specified in Part II 
only), contrast sensitivity, LLVA, 
 
 
Efficacy evaluation 
updated to include 
MAIA 
microperimetry; for 
Part II only,
have been 
added; specifies 
Octopus 900 for 
visual field only in 
Part II 
Synopsis  
Statistical 
Methodology 
Page 10 
The primary objective is 
to evaluate… 
The primary objective of Part I is to 
evaluate… 
Differentiates Part I 
objective from Part 
II objective 
 
The primary objective of Part II is 
to evaluate the efficacy and safety 
of AAV8-RPGR in an expanded 
population of subjects. 
Differentiates Part I 
objective from Part 
II objective 
A sample size of 30 
subjects at the MTD dose 
ensures that events with 
an incidence ≥10% will 
be identified with a 95% 
probability. 
In Part II, subjects will be 
randomized 1:1:1 to the 2 doses of 
AAV8-RPGR: 2.5 × 10^11 gp and 
5 × 10^10 gp or an untreated 
control group.   
Randomization 
clarification for 
Part II, with 
addition of 
untreated control 
group 
 
Fisher’s exact test will be utilized 
for the comparisons of binary 
endpoints, and T-test will be 
employed for the comparisons of 
continuous endpoints. 
Statistical methods 
to include Fisher’s 
exact test and T-
tests 
Section 6  
Study Objectives 
and Endpoints 
Page 20 
The primary safety 
endpoint is incidence of 
dose-limiting toxicities 
(DLTs) and treatment-
emergent adverse events 
(TEAEs) over a 24-month 
period. 
Endpoints 
Part I 
Primary Endpoints:  
The primary safety endpoints are the 
incidence of dose-limiting toxicities 
(DLTs), and treatment-emergent 
adverse events (TEAEs) over a 24-
month period.   
Secondary and Exploratory 
Endpoints: 
Separated out Part I 

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Rationale 
• Change from baseline in 
microperimetry at 3, 6, 12, 18 and 
24 months 
• Change from baseline in best-
corrected visual acuity (BCVA) at 
3, 6, 12, 18, and 24 months 
• Change from baseline in spectral 
domain optical coherence 
tomography (SD-OCT) at 3, 6,12, 
18 and 24 months 
• Change from baseline in 
autofluorescence at 3, 6, 12, 18 
and 24 months 
• Change from baseline in other 
anatomical and functional 
outcomes at 3, 6, 12 months, 18 
and 24 months 
Section 6.2.2 Study 
Objectives and 
Endpoints 
Page 20 
 
Part II 
Primary Efficacy Endpoint: 
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
Safety Endpoint: 
The safety endpoint is incidence of 
TEAEs over a 12-month period. 
Separated out Part 
II  
Section 6.2.2.3  
Study Objectives 
and Endpoints 
Page 20-21 
• Change from baseline 
in microperimetry at 3, 
6, 9, 12 18 and 24 
months 
• Change from baseline 
in best-corrected visual 
acuity (BCVA) at 3, 6, 
12 18 and 24 months 
• Change from baseline 
in SD-OCT at 3, 6, 12 
18 and 24 months 
• Change from baseline 
in autofluorescence at 
3, 6, 12, 18 and 24 
months 
Secondary Endpoints: 
• 
Change from baseline in 
microperimetry at 1, 6, 9, and 
12 months 
• 
Change from baseline in best-
corrected visual acuity (BCVA) 
at 3, 6, and 12 months 
• 
Change from baseline in SD-
OCT at 3, 6, and 12 months 
• 
Change from baseline in 
autofluorescence at 3, 6, and 12 
months 
• 
Change from baseline in visual 
field assessed by Octopus 900 
at 3, 6, and 12 months 
Updated Part II 
endpoints 

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• Change from baseline 
in other anatomical and 
functional outcomes at 
3, 6, 12, 18 and 24 
months 
Exploratory Endpoints: 
 
 
 
 
 
 
 
 
 
 
 
Updated Part II 
endpoints 
Section 7.1.  
Overall Design 
Pages 22-25 
-   Part II is a Maximum 
Tolerated Dose (MTD) 
expansion study (as 
determined in Part I). 
This is a Phase 1/2/3… 
 
The study will be conducted in two 
parts: Part I is a dose escalation 
study, Part II is a dose-expansion 
study, with 2 doses selected from 
Part I based on safety and efficacy, 
and a third untreated group to allow 
for a controlled comparison of 
efficacy.  
Part I will identify the maximum 
tolerated dose (MTD) using a dose-
escalation scheme. Part II will 
expand 2 doses, allowing for a 
broader assessment of the safety and 
efficacy of AAV8-RPGR with a 
larger sample size, including 45 
subjects randomized 1:1:1 to the a 
high-dose, a low-dose, and an 
untreated arm.  Part I primarily 
evaluates safety, defined by 
incidence of DLTs and TEAEs over 
a 24-month period.  Phase II 
evaluates safety and efficacy, with 
inclusion of a primary efficacy 
endpoint, improvement from 
Baseline in microperimetry, 
evaluated at 3 months, and safety 
and secondary efficacy evaluated at 
1-, 6-, 9- and 12 -months post-
treatment. 
All Part II subjects treated under 
previous versions of the protocol 
Updated study 
design overview 
for Parts I and II to 
include expanded 
description of 
individual parts 

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will be followed for 12 months with 
the pre-specified visit schedule. 
At study completion, all subjects 
will be invited to participate in a 
separate long-term follow-up study 
that will collect efficacy and safety 
data up to 5 years from surgery. 
The study will consist of  
visits over a 24-month 
evaluation period.   
Part I consists of 12 visits over a 24-
month evaluation period.  Part II 
consists of 10 visits over a 12-month 
period 
Differentiated Part 
I and Part II visit 
number and 
duration  
 
To minimise inflammation resulting 
from surgery and/or 
vector/transgene, in Part I, all 
subjects will be given a 21-day 
course of oral corticosteroid. 
In Part II, all subjects will be treated 
at the time of surgery with up to 1 
mL of triamcinolone (40 mg/mL), 
placed behind the globe via a deep 
sub-Tenon approach.  Subjects will 
also be given a 9-week course of 
oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, 
followed by 6 weeks of tapering 
doses. The dose regimen is adjusted 
for pediatric subjects treated in Part 
II (see Section 9.8). 
Subjects in the untreated control 
group will receive study-visit 
telephone calls to monitor 
AEs/SAEs and review concomitant 
medications on Visit 2 (Day 0) and 
on Visit 3 and 4 (post-operative 
Days 1 and 7). 
• To improve 
safety and to 
prevent potential 
inflammatory 
response to 
therapy, the 
steroid regimen 
has been 
modified.  A 
standardized 
adult starting 
dose of 60 mg 
has been selected 
(rather than the 
previous 1mg/kg 
starting dose) 
and the taper has 
been lengthened 
to include 
coverage out to 
approximately 2 
months. A 2-
month visit has 
been added to 
assess the 
subjects at the 
end of the steroid 
therapy. 
• The treatment of 
untreated 
subjects at Visits 
2, 3 and 4 has 
been added 
The efficacy evaluation 
will be based on BCVA, 
SD-OCT, fundus 
autofluorescence, 
The efficacy evaluation will be 
based on microperimetry, BCVA, 
SD-OCT, fundus autofluorescence, 
visual fields (Octopus 900 specified 
• 
 
 
 

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microperimetry, visual 
fields, contrast sensitivity, 
low luminance visual 
acuity (LLVA), full-field 
stimulus threshold test 
(FST), colour vision, and 
reading test.  Any safety 
information collected as a 
result of the efficacy 
assessments (e.g., BCVA) 
will also be used in the 
overall safety evaluation, 
as applicable. 
Subjects who develop 
cataracts may undergo 
cataract surgery if deemed 
clinically necessary; if 
surgery is performed, it 
should be carried out at 
least 4 weeks before Visit 
1 (Year 1) or Visit 11 
(Year 2). 
A subject is considered to 
have completed the study 
if he completes the Year- 
2 assessments.  The end of 
the trial is the date the last 
subject completes his 
Year- 2 assessments (or 
early termination [ET] 
assessments in the event of 
premature discontinuation) 
or the date of last data 
collection if the last 
subject is lost to follow-
up. 
in Part II only), contrast sensitivity, 
low luminance visual acuity 
(LLVA), 
 and 
 
 
 
Subjects who develop cataracts may 
undergo cataract surgery if deemed 
clinically necessary; if surgery is 
performed, it should be carried out at 
least 4 weeks before their final visit.  
A Part I subject is considered to 
have completed the study if he 
completes the Month-24 
assessments.  A Part II subject is 
considered to have completed the 
study if he completes the Month 12 
assessments.  
The end of the trial is the date the 
last subject completes his final-visit 
assessments (or early termination 
[ET] assessments in the event of 
premature discontinuation) or the 
date of last data collection if the last 
subject is lost to follow-up. 
 
; 
 
• All above only in 
Part II 
• Specified 
Octopus 900 
only in Part II for 
visual field 
assessment 
• Removed 
assessments that 
have caused 
unnecessary 
study burden in 
subjects and that 
have not 
provided 
valuable 
information in 
Part I 
• Differentiated 
duration in Part I 
and Part II as 
well as definition 
of study 
completion 
Section 7.1.3.   
Dose Expansion 
Page 25 
Once the MTD has been 
identified, uUp to 45 
additional subjects will be 
randomized, in a 2:1 
allocation ratio^ ^ .  
Subjects will receive 
AAV8-RPGR either at the 
MTD (MTD cohort), or at 
a low dose (active-control 
cohort), three dose-levels 
below the MTD (e.g., low 
dose = 5 5 x x 1010 gp if 
MTD = 5x1011 gp).   
Up to 45 additional subjects will be 
randomized in a 1:1:1 allocation 
ratio to a high-dose group (2.5 × 
10^11 gp), a low-dose group (5 × 
10^10 gp), and an untreated group.   
 
Study data will be collected for both 
eyes of each subject. Since treatment 
requires an invasive surgical 
procedure under general anaesthesia, 
the sponsor, investigator and the 
subject will be unmasked to the 
study procedure (i.e., vitrectomy and 
sub-retinal injection), however 
Part II description 
now identifies 
treatments as dose 
5 and dose 3 and 
untreated arm 
added, per general 
rationale (see 
above).  
Description of 
assessor masking 
added 

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Part II of the study will be 
randomized and double-
masked to the assigned 
dose, and open-label to the 
treatment administration. 
within the treated groups, the 
sponsor, investigator and subject 
will be masked to the assigned dose. 
To further minimise potential bias of 
the treated and non-treated eye 
evaluations, all subjective 
ophthalmic assessments at the 
Screening/Baseline Visit (Visit 1) 
and from Month 1 (Visit 5) onwards 
will be conducted by a masked 
assessor. 
Section 7.3  
Discussion of Study 
Design and Dose 
Selection 
Page 25-27 
The planned sample size is 
consistent with a 3+3 
escalation scheme.  A 
prospective trial period of 
24 months is considered to 
be a sufficient period of 
time to monitor for any 
AEs related to the vector 
and/or 
transgene/administration 
procedure.   
The planned sample size in Part I is 
consistent with a 3+3 escalation 
scheme.  A prospective trial period 
of 24 months is considered to be a 
sufficient period of time to monitor 
for any AEs related to the vector 
and/or transgene/administration 
procedure.   
Specified Part I for 
dose escalation 
Section 7.3 
Discussion of Study 
Design and Dose 
Selection 
Pages 25-27 
Further details are 
provided in the 
Investigator’s Brochure., 
and a summary of the 
AAV8-RPGR doses in the 
toxicology species is 
presented in the table 
below.  The safety and 
efficacy findings from 
other pre-clinical and 
clinical studies with 
AAV8 vector for 
subretinal delivery are also 
included for comparison. 
Further details are provided in the 
Investigator’s Brochure.Given 
previous experience demonstrating 
the safety of higher subretinal doses 
of AAV8 vector 
(Vandenberghe 2011), and lacking 
safety signals at the lower range of 
doses, it should be possible to dose-
escalate to the high end of the dose 
range of AAV8-RPGR 
This information 
was removed as it 
is redundant with 
the IB. 
The added 
language clarified 
the overall 
meaning.  
Table 1: Toxicology 
Safety Margin for Clinical 
Trials 
 
Eliminated the 
table from the 
protocol as this is 
redundant with the 
IB.  
Once the MTD has been 
identified and the safety 
and tolerability of AAV8-
RPGR is demonstrated in 
adults, subjects ≥10 year 
age will be enrolled in Part 
II of the study.  The 10-
years of age cut-off 
safeguards… 
Once Part I dose-escalation has been 
completed, and the safety and 
tolerability of AAV8-RPGR is 
demonstrated in adults, subjects ≥10 
years of age will be enrolled in Part 
II of the study.  The 10-years of age 
cut-off safeguards… 
Clarified that dose 
escalation 
completion is 
trigger to Part II 

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In Part II, subjects will be 
randomized to ‘MTD 
cohort’ or the ‘active-
control  The active-control 
cohort will be three dose-
levels below the MTD. 
This assures a 1-1.5-log 
difference in dose between 
these two cohorts, and 
allows for identifying a 
dose response while 
mitigating the possibility 
of a subtherapeutic low 
dose. 
In Part II, subjects will be 
randomized to a high-dose (2.5 × 
10^11 gp), a low-dose (5 × 10^10 
gp), and an untreated group.   This 
allows for comparisons in a 
randomized and controlled fashion, 
as recommended by regulators for 
best practices in ophthalmic gene 
therapy studies (Human Gene 
Therapy for Retinal Disorders, Draft 
Guidance for Industry July 2018). 
The sponsor, investigator and the 
subject will be unmasked to the 
study procedure and treatment (i.e. 
vitrectomy and sub-retinal 
injection). However, within the 
treated groups, the sponsor, 
investigator and subject will be 
masked (i.e. double-masked) to the 
assigned dose. To further minimise 
potential bias of the treated and non-
treated eye evaluations, all 
subjective ophthalmic assessments at 
the Screening/Baseline Visit (Visit 
1) and from Month 1 (Visit 5) 
onwards will be conducted by a 
masked assessor. 
Part II description 
now identifies 
treatments as dose 
5 and dose 3 and 
untreated arm 
added, per general 
rationale (see 
above).  
 
Added description 
of masking 
procedures 
Section 8.0 
Selection and 
Withdrawal of 
Subjects 
Page 28 
 
8.1 Part I 
Differentiating Part 
I and Part II 
inclusion criteria to 
improve clarity 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Pages 28 
Subject / parent (if 
applicable) is willing and 
able to give informed 
consent for participation in 
the study 
 
• Part I is only in 
adults so removed 
the language for 
minors 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Page 28 
3. Are male and able to 
comply and adequately 
perform all study 
assessments 
Part I:≥18 years of age 
Part II: ≥10 years of age 
Part I 
Are male, ≥18 years of age, and able 
to comply and adequately perform 
all study assessments. 
Clarified age 
inclusion for Part I;  
• separated Part I 
and Part II 
inclusion to add 
clarity for 
investigators; 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Page 28 
5. BCVA in both eyes that 
meets the following 
criteria, based on the 
cohort level: 
5. BCVA in both eyes that meets the 
following criteria, based on the 
cohort level: 
Cohort 4-6: better than or equal to 
BCVA of 34 ETDRS letters 
• Removed Part II 
because inclusion 
criterion is now 
separated for Part 

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Cohort 4-6 and study 
Part II: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better 
than or equal to 6/60 
or 20/200 Snellen 
acuity) 
 
(equivalent to better than or equal to 
6/60 or 20/200 Snellen acuity) 
II to improve 
clarity 
Section 8.1.1 
Selection and 
Inclusion Criteria 
Page 28 
Prior documentation… 
Documentation 
• Clarified 
documentation 
requirement 
Section 8.2  
Part II 
Section 8.2.1 
Inclusion Criteria 
Page 28 
 
Part II 
• Differentiating 
Part I and Part II 
inclusion criteria 
to improve clarity 
Section 8.2  
Part II 
Section 8.2.1 
Inclusion Criteria 
Pages 28-29 
 
Part II 
Inclusion Criteria 
1. Subject / parent (if applicable) is 
willing and able to provide informed 
consent for participation in the study 
2. Are male, ≥10 years of age, and 
able to comply and adequately 
perform all study assessments 
3. Documentation of a non-
synonymous mutation in the RPGR 
gene 
4. Have active disease clinically 
visible within the macular region in 
the study eye and defined as follows: 
 ellipsoid zone (EZ) on SD-OCT at 
screening must be measurable, and 
within the nasal and temporal 
border of any B-scan, and not be 
visible on the most inferior and 
superior B-scan 
5.Have a BCVA in the study eye 
that meets the following criteria: 
•Better than or equal to BCVA of 34 
ETDRS letters (equivalent to better 
than or equal to 6/60 or 20/200 
Snellen acuity). 
6. Mean total retinal sensitivity in 
the study eye as assessed by 
microperimetry ≥0.1 dB and ≤8 dB  
• Added section for 
Part II inclusion 
criteria to clarify 
the differences 
between Parts I 
and II; 
• EZ zone must be 
measurable on 
screening in the 
study eye 
• BCVA is same for 
all subjects in Part 
II (no cohort 
differences); 
specifies criterion 
is for study eye 
only 
• Added mean total 
retinal sensitivity 
range in the study 
eye to ensure that 
subjects have 
modifiable 
microperimetry 
not subject to 
ceiling effects 

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Section 8.3.  
Exclusion Criteria: 
Parts I and II  
Page 29 
 
Parts I and II 
To clarify that 
exclusion criteria 
are the same for 
Parts I and II 
Section 9.1 
Treatments 
Administered 
Page 31 
At the Injection Day Visit 
(Visit 2, Day 0), subjects 
will undergo vitrectomy 
and retinal detachment in 
their study eye and then 
receive a single, sub-
retinal injection of AAV8-
RPGR (See Section 9.4 for 
details). 
Part I, Dose Escalation, Phase 1: all 
subjects will undergo vitrectomy and 
retinal detachment in their study eye 
and then receive a single, sub-retinal 
injection of AAV8-RPGR (See 
Section 9.4 for details). 
Part II, Dose Expansion, Phase 2/3: 
Subjects will be assigned to 1 of the 
following: high-dose (2.5 × 10^11 
gp), low-dose (5 × 10^10 gp), or an 
untreated control arm. 
Clarified the 
treatments in Part I 
and Part II 
Section 9.3.  
Packaging, 
Labeling, 
Preparation and 
Storage 
Page 31 
The Investigational 
Medicinal Product will be 
labelled in compliance 
with regulatory standards. 
(on either the primary or 
secondary container) and 
include the protocol study 
number, Sponsor’s name, 
product name, titre, vial 
and lot number, expiration 
date, (IMP labellied for 
Europe only) storage 
conditions and caution 
statement. 
The Investigational Medicinal 
Product (IMP) will be labelled in 
compliance with regulatory 
standards. 
Deleted label 
information. 
Section 9.4 
Vitrectomy 
Procedure and 
Injection of AAV8-
RPGR 
Pages 31 
 
The subretinal injection technique to 
be used in this study is similar to 
that developed in the sponsor’s 
choroideremia programme in 
Oxford… To date, over 150 subjects 
have been injected without 
complication by retinal surgeons 
using the technique described below. 
All subjects will be treated at the 
time of surgery with up to 1 mL of 
triamcinolone (40 mg/mL), placed 
behind the globe via a deep sub-
Tenon approach. 
Updated vitrectomy 
procedure 
background and 
added description 
of additional local 
steroid 
administration at 
the time of surgery 
Section 9.5 
Randomisation 
Page 33 
The dose-escalation 
portion of this study is not 
randomized. 
 
In Part II, after the study 
eye is assigned, subjects 
will be randomised a 2:1 
ratioAAV8-RPGR MTD 
Part I, the dose-escalation portion of 
this study, is not randomized. 
In Part II, after the study eye is 
assigned, subjects will be 
randomised to 1 of 3 groups with a 
1:1:1 allocation ratio: 1) treatment 
with AAV8-RPGR at a high dose 
(2.5 × 10^11 gp); 2) treatment with 
Part II 
randomization 
procedure added; 
doses identified as 
dose 5 and dose 3 
and untreated arm 
added, per 

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or a lower dose of AAV8-
RPGR, three dose-levels 
from MTD (e.g., low dose 
= 5 x 1010 gp if MTD = 
5x1011 gp) for the active-
control cohort.   
AAV8-RPGR at a low dose (5 × 
10^10 gp) or 3) no treatment.   
introductory 
general rationale.  
Section 9.6.   
Study Masking 
Page 33-34 
Part II is double-masked 
(subject, surgeon, 
investigator/site team, 
sponsor will be masked to 
the assigned dose, and 
open-label with respect to 
the treatment 
administration). 
In Part II, all ophthalmic 
assessments that are conducted at the 
Screening/Baseline Visit will be 
conducted by appropriately qualified 
masked assessors.  For the 
immediate post-operative visits, 
masking of the assessors will not be 
viable as clinical signs of surgery 
will be apparent (i.e. redness, 
swelling). Therefore, unmasked 
assessors will perform all 
ophthalmic assessments at Visit 3 
(Day 1) and Visit 4 (Day 7). For 
Visit 5 (Month 1) onwards, masked 
assessors will be used, as any signs 
of surgery will have dissipated and it 
will not be possible clinically to 
differentiate between those subjects 
that have not undergone surgery, and 
those subjects that have undergone 
surgery and received active 
treatment. 
Subjects randomised to the untreated 
Control group will not be required to 
attend the site at Visit 2, 3 or 4. As 
the key purpose of Visit 2 is surgery, 
and Visit 3 and 4, post-operative 
safety, there is limited utility in 
Control subjects attending. 
Therefore, to limit the study burden 
for Control subjects thereby 
potentially reducing the risk of 
subject withdrawal at this stage and 
reducing the possibility of further 
unmasking due to direct contact and 
communication with fellow 
participants, Control subjects are not 
scheduled to attend the clinic for 
study visits at these times. 
In order to minimise bias further, 
masked assessors will not have 
access to the subject’s medical 
records, source documentation or 
eCRF as data entries or notation 
Clarified masking 
procedure 

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(such as use of peri-operative 
corticosteroid) may be sources of 
unmasking. From Visit 5 (Month 1) 
onwards, the masked assessor will 
also read a pre-written statement to 
each subject, regardless of 
randomisation, reminding them of 
the masked nature of the study, and 
to avoid any reference to prior 
surgery/non-surgery, which eye may 
have received treatment or to allude 
to any information that may unmask 
the assessor as to which group the 
subject has been assigned to.  
Furthermore, it is anticipated that a 
subset of the subjects participating in 
the trial will be active on social 
media. Following appropriate 
approval by the Independent Ethics 
Committee (IEC)/Institutional 
Review Board (IRB), the patient 
information leaflet will request that 
subjects refrain from posting any 
details of study participation on 
social media, that may unmask the 
assessors to the group the subject 
has been assigned to. This request 
will be reiterated at subject visits by 
the investigator and within the pre-
written statement. 
Subjects randomised to the AAV8-
RPGR treatment groups, surgeons, 
the investigative team and the study 
sponsor will be masked to which 
dose of AAV8-RPGR the subject 
has been assigned to. Unmasked 
study site personnel will be assigned 
the responsibility of performing 
dilution, which will take place in a 
designated area remote from the 
investigative team to preserve 
masking of the treatment arm. 
Personnel delegated to perform the 
dilution will not be involved in any 
other aspect of the study (i.e., 
consent, safety/efficacy assessments, 
surgical procedure). 
Section 9.8 
Concomitant 
Therapy 
 
To minimise inflammation, at the 
time of surgery, all subjects will be 
• To improve 
safety and to 

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treated with a course of 
corticosteroid. 
In Part I, all subjects will also be 
prescribed a 21-day course of oral 
prednisone/prednisolone, following 
closely the 17-day protocol 
established in the Philadelphia AAV 
gene therapy clinical trial (Maguire 
et al., 2008), except allowing an 
extra 4 days for tapering the dose at 
the end of the course, i.e., 
1 mg/kg/day prednisone / 
prednisolone for a total of 10 days 
(beginning 2 days before the vector 
injection, on the day of injection, 
and then for 7 days); followed by 
0.5 mg/kg/day for 7 days; 
0.25 mg/kg/day for 2 days; and 
0.125 mg/kg/day for 2 days (21 days 
in total. 
 
In Part II, at the time of surgery, all 
subjects (adult and pediatric) will be 
treated with up to 1 mL of 
triamcinolone, 40 mg/mL solution, 
which must be placed behind the 
globe via a deep sub-Tenon 
approach.  In addition, all subjects 
will be prescribed a course of oral 
corticosteroids. 
For adults, 60 mg of oral prednisone 
/ prednisolone will be prescribed for 
the initial 21 days (starting 3 days 
prior to surgery), followed by a 
weekly taper as follows for a total of 
9 weeks of treatment: 
Day -3 through day 17 (21 days): 
60 mg by mouth once daily 
Day 18 through day 24 (7 days): 
50 mg by mouth once daily 
Day 25 through day 31 (7 days): 
40 mg by mouth once daily 
Day 32 through day 38 (7 days): 
40 mg by mouth once daily 
Day 39 through day 45 (7 days): 
20 mg by mouth once daily 
Day 46 through day 52 (7 days): 
10 mg by mouth once daily 
prevent potential 
inflammatory 
response to 
therapy, the 
steroid regimen 
has been 
modified.  A 
standardized 
adult starting 
dose of 60 mg 
has been selected 
(rather than the 
previous 1mg/kg 
starting dose) 
and the taper has 
been lengthened 
to include 
coverage out to 
approximately 2 
months. A 2-
month visit has 
been added to 
assess the 
subjects at the 
end of the steroid 
therapy. 
• A pediatric 
regimen has also 
been added 
• General safety 
information 
regarding the use 
of steroids has 
been added 

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Day 53 through day 59 (7 days): 5 
mg by mouth once daily.  
 
If at the Month-2 visit (Visit 5.9), 
inflammation is observed, 
corticosteroid therapy should be re-
initiated, via oral and/or intraocular 
route, based on the clinical condition 
of the subject, and the judgement of 
the investigator. 
For pediatric subjects, oral 
prednisolone/prednisone will also be 
started 3 days prior to surgery. The 
starting dose will be based on 
kilogram weight of the subject, up to 
a maximum of 60 mg starting dose 
(rounded to the nearest 1 mg). 
Subsequent doses will have 
multipliers to provide the 
appropriate taper over an additional 
6 weeks, for a total of 9 weeks of 
treatment.  See tapering regimen for 
pediatric subjects below: 
Day -3 through day 17 (21 days): 
Starting Dose (SD) 1 mg/kg by 
mouth once daily (maximum dose 
of 60 mg/once daily) 
Day 18 through day 24 (7 days): 
SD X 0.83 mg by mouth once 
daily 
Day 25 through day 31 (7 days): 
SD X 0.67 mg by mouth once 
daily 
Day 32 through day 38 (7 days): 
SD X 0.5 mg by mouth once daily 
Day 39 through day 45 (7 days): 
SD X 0.33 mg by mouth once 
daily 
Day 46 through day 52 (7 days): 
SD X 0.17 mg by mouth once 
daily 
Day 53 through day 59 (7 days): 
SD X 0.08 mg by mouth once 
daily 
If at the Month-2 visit (Visit 5.9), 
inflammation is observed, 
corticosteroid therapy should be 
reinitiated, via oral and/or 
intraocular route, based on the 
clinical condition of the subject, and 
the judgement of the investigator.  
The local pediatric team should be 
involved with all children 
undergoing gene therapy surgery 
and should be available to give 
advice on the steroid doses used in 

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each patient.  Modification of the 
protocol-defined steroid treatment 
are allowed based on 
recommendations of the pediatric 
team with approval from the 
Sponsor.  
For all subjects, while taking oral 
steroids, special note should be 
made to follow for potential side 
effects (e.g., increased IOP, 
cataracts, hypertension, elevated 
blood sugar, infections, 
gastritis/peptic ulcer disease, edema, 
electrolyte imbalance, mood 
changes, insomnia), and appropriate 
prophylaxis and/or therapy should 
be instituted as needed (e.g., 
treatment with proton pump 
inhibitors and/or valcyclovir; 
restriction of nonsteroidal anti-
inflammatory agents) 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Pages 37-38 
 
The subject or parent will sign and 
date one copy of the consent form in 
the presence of the investigator or 
his/her designee; where applicable, 
an assent form will be completed by 
the subject. 
• Moved for 
clarity 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Pages 38 
• For Part I, RPGR gene 
mutation screen (only if 
not conducted 
previously); for Part II, 
prior documentation of 
a non-synonymous 
mutation in the RPGR 
gene  
• Colour vision test  
• Speed reading test 
• FST  
Footnote: 
It is recommended to 
measure BCVA and 
LLVA twice on the first 
day and once on the 
second day (prior to pupil 
dilation).  All 3 BCVA 
and all 3 LLVA values 
must be recorded in the 
eCRF.  The highest BCVA 
score will be used to 
• For Part I, RPGR gene mutation 
screen (only if not conducted 
previously); for Part II, 
documentation of a non-
synonymous mutation in the 
RPGR gene  
• ETDRS BCVA1 
 
 
• Fundus autofluorescence 
• MAIA Microperimetry4 
• Fundus photography 
• Octopus 900 visual fields4,5 
• Contrast sensitivity test 
• 
AE and SAE monitoring 
 
 
 
 
• Randomisation3 
Footnotes: 
1. For Part I subjects, BCVA is 
performed in triplicate at baseline. 
For Part II subjects, if the BCVA 
• Includes 
specifics on 
genetic 
diagnosis 
criterion 
• Assessments at 
Visit 1 now 
include AO-
OCT,
 
 
• Specifies 
Octopus 900 
visual field 
• AE and SAE 
monitoring will 
occur from 
screening 
through end of 
study instead of 
SAE monitoring 
only 

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Version 8.0, 18 DEC 2018 
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define subject eligibility.  
LLVA should be 
conducted immediately 
after each BCVA 
assessment.   
value at Visit 1 
(Screening/Baseline) is ≥ ± 10 
letter gain or loss in the study eye 
compared to the previous 
XOLARIS study visit (if 
applicable), then BCVA must be 
repeated an additional 2 times, 
resulting in a total of 3 BCVA 
measures at Visit 1.  
For Part II subjects, if the BCVA 
value at Visit 1 
(Screening/Baseline) is < ± 10 
letter difference in the study eye 
compared to the previous 
XOLARIS study visit, then BCVA 
will be collected once and will not 
be repeated. 
If subject was not previously in 
XOLARIS study, BCVA 
assessments at baseline must be 
triplicate. 
For all subjects who require 
triplicate BCVA testing, to 
facilitate the additional BCVA 
measures, this visit should be 
conducted over 2 days, with 
BCVA measured twice on Day 1 
and once on Day 2 (prior to pupil 
dilation). All 3 BCVA values must 
be recorded in the eCRF. The 
highest score will be used to 
define subject eligibility. 
 
 
. 
3. Part II only. 
4. Assessments collected in 
triplicate.  To facilitate triplicate 
testing, the visit should be 
conducted over 2 days. Visual 
field and microperimetry outputs 
will be sent to a CRC for review.  
Data will be generated and 
collated within the CRC and 
exported to the Sponsor or 
designee for inclusion in the study 
database. 
• Removed 
reading test, 
colour vision 
and FST 
• Removed 
footnote 
information 
regarding 
BCVA and 
LLVA; added 
information in 
footnote related 
to Octopus 900 
and new 
assessments 
• Added new 
information 
regarding 
baseline BCVA 
assessment 
requirements 
• 
 
 
 
 
• Specified in 
footnote that 
Octopus 900 is 
only specified in 
Part II 
• Moved text for 
BCVA  timeline 

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SUMMARY OF CHANGES  
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5. Octopus 900 perimetry is 
specified for visual field assessments 
only in Part II.  
 
 
 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Page 38 
In Part II, subjects will be 
then randomised to one of 
the AAV8-RPGR 
treatment groups (MTD 
cohort or active-control 
cohort) and subjects 
receiving treatment will 
remain masked to the 
treatment dose.   
In Part II, subjects will be informed 
of the randomisation outcome (i.e., 
AAV8-RPGR treatment or the 
Control group) and instructed to not 
reveal their treatment group 
assignment to the masked assessors 
during the study. Subjects 
randomised to the AAV8-RPGR 
treatment groups (along with the 
Investigators and sponsor) will 
remain masked to the assigned dose. 
New randomization 
and treatments 
specified 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Page 38 
Subjects will be given a 
21-day course of oral 
prednisone/prednisolone 
Subjects will be given a 21-day 
course of oral 
prednisone/prednisolone and 
instructed to start taking the drug 2 
(Part I) or 3 (Part II) days before 
their next study visit (Visit 2). 
Steroid course is no 
longer 21 days for 
all subjects 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Page 38 
Footnote 1 
 
For Part II subjects, if… 
Clarified for Part II 
subjects 
For all subjects who require 
triplicate BCVA testing, to facilitate 
the additional BCVA measures, this 
visit should be conducted over 2 
days, with BCVA measured twice 
on Day 1 and once on Day 2 (prior 
to pupil dilation). All 3 BCVA 
values must be recorded in the 
eCRF. The highest score will be 
used to define subject eligibility. 
Added  text to 
specify subjects and 
added information 
moved from 
previous location 
, and 
Clarified grammar 
Section 10.2  
Visit 2 
(Day 0, 
Surgery/Injection 
Day Visit) 
Pages 38-39 
 
At Visit 2, all subjects in the AAV8-
RPGR groups will visit the surgical 
site, and the following assessments 
will be performed prior to surgery: 
• Full ophthalmic examination, 
including indirect ophthalmoscopy, 
slit lamp examination with IOP 
assessment, anterior chamber and 
vitreous inflammation grading, and 
LOCS III cataract grading 
 
• Ophthalmic exam 
has been added 
• Language added 
because one arm 
is untreated in 
Part II 
• Added language 
specifying that 
other non-study 
procedures may 
be necessary but 

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It may be necessary for subjects to 
undergo a pre-surgical workup 
according to local hospital 
procedures (e.g., blood draw for 
anesthetist) which are outside of the 
protocol-defined assessments. Any 
assessments performed outside of 
the protocol will not be collected as 
part of the study analyses. 
All subjects will be treated at the 
time of surgery with up to 1 mL of 
triamcinolone (40 mg/mL), placed 
behind the globe via a deep sub-
Tenon approach. 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time. 
Sites will conduct the following 
assessments during the telephone 
call: 
• 
AE/SAE monitoring 
• 
Concomitant medication 
review. 
will not be 
collected 
• Added new local 
steroid therapy 
added at time of 
surgery 
• Added how the 
untreated arm 
will be assessed 
through a 
telephone call at 
that visit. 
Section 10.2 Visit 2 
(Day 0/ 
Surgery/Injection 
Day Visit) 
Page 38-39 
Footnote 
 
• 
Corticosteroid compliance 
review1 
1.  Corticosteroid review is 
applicable only for treated subjects. 
• Added footnote 
that specifies 
corticosteroid 
review is only for 
treated subjects.  
Section 10.3  
Visit 3  
(Day 1 Post-
Operative Visit) 
Page 39 
 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time.  
Sites will conduct the following 
assessments during the telephone 
call: 
• 
AE/SAE monitoring 
• 
Concomitant medication 
review. 
Added how the 
untreated arm 
will be assessed 
through a 
telephone call at 
that visit. 
Section 10.3 Visit 3 
(Day 1 Post-
operative Visit) 
Page 39 
Footnote 
 
• 
Corticosteroid compliance 
review1 
1.  Corticosteroid review is 
applicable only for treated subjects. 
Added footnote 
that specifies 
corticosteroid 
review is only for 
treated subjects.  
Section 10.4 Visit 4 
(Day 7 Post-
Operative Visit) 
Page 40 
 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time.  
Sites will conduct the following 
Added how the 
untreated arm 
will be assessed 
through a 

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SUMMARY OF CHANGES  
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assessments during the telephone 
call: 
• 
AE/SAE monitoring 
• 
Concomitant medication 
review. 
telephone call at 
that visit. 
Section 10.4 Visit 4 
(Day 7 Post-
operative Visit) 
Page 40 
Footnote 
 
• 
Corticosteroid compliance 
review1 
1.  Corticosteroid review is 
applicable only for treated subjects. 
Added footnote 
that specifies 
corticosteroid 
review is only for 
treated subjects.  
Section 10.5   
Visit 5 (Month 1) 
Page 40-41 
 
• MAIA Microperimetry 
• Specified MAIA 
microperimetry  
Section 10.5 Visit 5 
(Month 1 Visit) 
Page 41 
Footnote 
 
• 
Corticosteroid compliance 
review1 
• 1.  Corticosteroid review is 
applicable only for treated 
subjects. 
• Added footnote 
that specifies 
corticosteroid 
review is only for 
treated subjects.  
Section 10.6   
Visit 5.9 (Month 2) 
Page 41 
 
At Visit 5.9, the following 
assessments will be performed: 
• Collection of safety blood samples 
(haematology and clinical 
chemistry) 
• Full ophthalmic examination, 
including indirect 
ophthalmoscopy, a slit-lamp 
examination, IOP, anterior 
chamber and vitreous 
inflammation grading and LOCS 
III cataract grading 
• ETDRS BCVA 
• SD-OCT 
• Fundus autofluorescence 
• MAIA Microperimetry 
• Viral shedding 
• Immunogenicity sampling 
• AE/SAE monitoring 
• Concomitant medication review 
• Corticosteroid compliance review 
New visit added to 
better monitor 
safety of subjects 
This visit is 
denoted as Visit 5.9 
in order to maintain 
the visit numbering 
in the EDC 
Section 10.6 Visit 6 
(Month 2 Visit) 
Page 41 
Footnote 
 
• 
Corticosteroid compliance 
review1 
• 1.  Corticosteroid review is 
applicable only for treated 
subjects. 
• Added footnote 
that specifies 
corticosteroid 
review is only 
for treated 
subjects.  

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Section 10.7   
Visit 6 (Month 3) 
Page 41-42 
• 
Colour vision test 
Footnote: 
It is recommended to 
measure BCVA and 
LLVA twice on the first 
day and once on the 
second day (prior to pupil 
dilation).  All 3  BCVA 
and all 3 LLVA values 
must be recorded in the 
eCRF.  LLVA should be 
conducted immediately 
after each BCVA 
assessment.    
• 
Fundus 
photography 
• 
Viral shedding 
• MAIA Microperimetry 
• Octopus 900 visual fields1 
 
 
Footnotes: 
 
1. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
 
 
• Month 3 added 
new 
assessments;  
• removed color 
vision test 
• specified MAIA 
microperimetry 
 
 
 
 
 
 
• Specified in 
footnote that 
Octopus 900 is 
only specified in 
Part II 
•  Removed 
footnote 
information in 
BCVA and 
LLVA 
• Removed 
assessments not 
done at visit 
Section 10.8. 
Visit 7 (Month 6) 
Pages 42 
• 
Colour vision test 
• 
Speed reading 
test 
• 
FST 
• 
Fundus 
photography 
 
 
• 
MAIA Microperimetry 
• 
Octopus 900 visual fields2 
 
 
Footnotes: 
 
 
 
2. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
• Removed color 
vision, speed 
reading, fundus 
photography, and 
FST; 
 
 
 
 
 
•  specifies MAIA 
microperimetry 
and Octopus 900 
visual field 
Section 10.9. 
Visit 8 (Month 9) 
Page 42-43 
• 
Fundus 
autofluorescence 
 
• MAIA Microperimetry 
• Removed 
autofluorescence; 
• MAIA 
microperimetry 
specified 

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Section 10.10. 
Visit 9 (Year 1) 
Pages 43 
• 
Colour vision test  
• 
Speed reading 
test 
• 
FST 
• 
BCVA1 
 
 
• 
MAIA Microperimetry 
• 
Octopus 900 visual fields3 
 
 
 
Footnote: 
1. (see below) 
 
 
 
 
3. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
 
 
Subjects who develop cataracts may 
undergo cataract surgery if deemed 
clinically necessary; if surgery is 
performed, it should be carried out at 
least 4 weeks before Visit 9 (Year 1) 
or Visit 11 (Year 2) for Part II and 
Part I subjects, respectively.   
• Removed color 
vision, reading 
and FST 
• Added 
 
  
• Specified MAIA 
microperimetry 
and Octopus 900 
visual field with 
associated 
footnotes 
• Differing times 
for Part I and 
Part II for 
window between 
potential cataract 
surgery and end 
of study visits 
 
 
 
 
 
 
• Specified in 
footnote that 
Octopus 900 is 
only specified in 
Part II 
ETDRS BCVA1 
Clarified  footnote 
for BCVA 
assessments in 7.1 
OCT1 
 
OCT2 
 
Updated footnote  
fields2 
fields3 
Updated footnote  
 
 
  
 
 
  
 
1. Part I subjects perform BCVA 
assessments in triplicate at 
Year  1.  To facilitate the 
additional BCVA measures, this 
visit should be conducted over 2 
days, with BCVA measured 
twice on Day 1 and once on 
Day 2 (prior to pupil dilation). 
Clarified  footnote 
for BCVA 
assessments for 
Part I subjects only 
in 7.1 

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All 3 BCVA values must be 
recorded in the eCRF. 
 
2, 3 
2., 3, 4 
Updated footnote 
numbers to 
accommodate new 
footnote 1 added. 
Section 10.11. 
Visit 10 (Month 18) 
Page 44 
 
(Part I Subjects Only) 
Specified that Visit 
11, Month 18 is 
only for subjects of 
Part I 
MAIA 
Added to 
Microperimetry 
Section 10.12. 
Visit 11 (Year 2) 
Page 44 
• 
Colour vision test  
• 
Speed reading test 
• 
FST  
(Part I Subjects Only) 
• Specified that 
Visit 12, Month 
24 is only for 
subjects of Part I 
• Removed 
assessments 
• 
MAIA 
• Added to 
Microperimetry 
• 
ETDRS BCVA1 
1. Part I subjects perform BCVA 
assessments in triplicate at Year 2.  
To facilitate the additional BCVA 
measures, this visit should be 
conducted over 2 days, with BCVA 
measured twice on Day 1 and once 
on Day 2 (prior to pupil dilation). 
All 3 BCVA values must be recorded 
in the eCRF. 
• Specified that 
BCVA 
assessments are 
performed in 
triplicate at 
years 2 and visit 
should be 
conducted over 2 
days. 
Section 10.13 
Early Termination 
(ET) Visit 
Page 45 
• Colour vision test  
• Speed reading test 
• FST 
 
 
• MAIA Microperimetry 
• Octopus 900 visual fields2 
 
 
 
Footnotes: 
 
 
2. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
3. Immunogenicity sampling at the 
ET Visit is to be conducted only if 
visit occurs prior to Year 1 visit. 
4. Part II only. 
• Added to ET 
visit, if possible, 
, MAIA 
Microperimetry, 
, and 
associated 
footnotes 
• Removed colour 
vision test, 
reading test, FST 
 
 
 
Section 10.13 
•  Immunogenicity sampling3 
• Added footnote 

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Early Termination 
(ET) Visit 
Page 45 
 
• 254 
• Updated footnote 
• Immunogenicity sampling at the 
ET Visit is to be conducted only if 
visit occurs prior to Year 1 visit. 
• Footnote added 
to clarify 
assessment 
requirements 
• 4., and 
• Updated footnote 
number, clarified 
grammar 
Section 10.14 
Unscheduled Visits 
Page 45-46 
 
• Autofluorescence 
• Added 
assessment to 
visit 
• MAIA 
• Added to 
Microperimetry 
• Microperimetry, if clinically 
feasible 
• Added 
microperimetry 
to unscheduled 
visit, if clinically 
feasible 
Section 11.1  
Best Corrected 
Visual Acuity 
Page 47 
BCVA will be performed 
in triplicate over a 2-day 
period at Visits 1,9 and 11  
(or ET Visit) for all 
subjects.  It is 
recommended that BCVA 
will be conducted twice on 
the first day and once on 
the second day. All values 
will be entered in the 
eCRF. 
For Part I subjects, BCVA will be 
performed in triplicate over a 2-day 
period at Visits 1, 9 and 11 (or ET 
Visit) for all subjects.  It is 
recommended that BCVA will be 
conducted twice on the first day and 
once on the second day. All values 
will be entered in the eCRF. 
 
For Part II subjects, if the BCVA 
value at Visit 1 
(Screening/Baseline) is ≥ ± 10 letter 
gain or loss in the study eye 
compared to the previous 
XOLARIS study visit (if 
applicable), then BCVA must be 
repeated an additional 2 times, 
resulting in a total of 3 BCVA 
measures at Visit 1. To facilitate the 
additional BCVA measures this visit 
should be conducted over 2 days, 
with BCVA measured twice on Day 
1 and once on Day 2 (prior to pupil 
dilation). All 3 BCVA values must 
be recorded in the eCRF. The 
highest score will be used to 
determine subject eligibility. 
If the BCVA value at Visit 1 
(Screening/Baseline) is < ± 10 letter 
difference in the study eye 
New instructions 
on BCVA 
triplicate 
requirement 

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compared to the previous 
XOLARIS study visit, then BCVA 
will be collected once and will not 
be repeated. 
If subject was not previously in 
XOLARIS study, BCVA 
assessments at baseline must be 
performed in triplicate. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
•
 
 
 
Section 11.5  
MAIA 
Microperimetry 
Page 48 
 
MAIA Microperimetry will be 
conducted for both eyes at the times 
indicated in Table 3, Section 17.1.  
Microperimetry will be performed 
on both eyes in triplicate over a 2-
day period at Visit 1 for all subjects. 
The final assessment should be used 
to determine subject eligibility.  
If at subsequent visits there are 
obvious technical challenges or the 
subject is not performing the 
assessment as expected from 
previous visits (e.g. distracted, large 
number of false positive responses, 
not maintaining fixation, etc), then 
the assessment may be repeated and 
the second assessment should be 
used for that study visit.  
Specifies that 
MAIA 
microperimetry 
will be performed 
in triplicate at Visit 
1 only or if there is 
an inconsistent 
reading at other 
visits  
Section 11.6  
Visual Fields 
Page 48 
 
In Part II, visual fields should be 
assessed using the Octopus 900 
perimeter. 
Specifies that 
Octopus 900 visual 
field will be 
conducted during 
Part II. 
Section 11.7. 
Contrast Sensitivity 
Page 49 
Contrast sensitivity will be 
measured prior to pupil 
dilation using a Pelli 
Robson chart. 
 
No longer specifies 
using the Peli-
Robson chart. 

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Section 11.8 
Low Luminance 
Visual Acuity 
Page 49 
The test should be 
performed after before 
BCVA testing and prior to 
pupil dilation. 
 
 
 
 
LLVA should be 
performed in triplicate 
over a 2-day period at 
Visit 1 and , Visit 9 8 
(Month 3) and Visit 11 (1 
Year) (or the ET Visit) for 
all subjects, if applicable.  
It is recommended that 
LLVA will be conducted 
twice on the first day and 
once on the second day. 
All values will be entered 
into the eCRF. 
The test should be performed before 
BCVA testing and pupil dilation. 
LLVA is no longer 
conducted in 
triplicate; it is now 
conducted prior to 
BCVA testing 
instead of after 
Full Field Stimulus 
Threshold Test 
Page 52 
FST will be measured for 
both eyes after a period of 
dark adaptation and at the 
times indicated in Table 3, 
Section 17.1 (Visit 1, 7, 9, 
11, ET) only at sites where 
the required FST 
equipment is available, as 
specified in the Study 
Operations Manual.  FST 
measurements will be 
taken by appropriately 
qualified technicians.  For 
complete technical 
specifications, refer to the 
Study Operations Manual. 
 
Removed 
assessment 
Colour Vision 
Page 52 
Colour vision will be 
tested for both eyes prior 
to pupil dilation, at the 
times indicated in Table 3, 
Section 17.1.  Eyes will be 
tested separately and in the 
same order at each 
assessment.  
For colour vision testing, 
assessors will be 
appropriately qualified for 
conducting the 
assessment.   
 
Removed 
assessment 

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Section, Page 
Previous Text  
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Reading Test 
Page 52 
Reading performance will 
be evaluated prior to pupil 
dilation for both eyes at 
the times indicated in 
Table 3, Section 17.1.  The 
reading test will be 
provided to each site by 
the Sponsor; for complete 
user instructions, refer to 
the Study Operations 
Manual.  
For the reading test, 
assessors will be 
appropriately qualified for 
conducting the 
assessment.   
 
Removed 
assessment 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
  
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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only in countries in which it is 
validated. 
Section 12.2.2 
Recording of 
Adverse Events 
Page 51 
 
AEs/SAEs… 
 
AEs/SAEs that the investigator 
becomes aware of, and which are 
deemed to have a relationship to the 
study drug should continue to be 
reported to NightstaRx following the 
completion of the study for a period 
of up to 5 years following surgery, 
until/unless the subject is enrolled in 
another NightstaRx study. 
AEs and SAEs will 
be collected from 
the time of 
informed consent 
to the end of study. 
 
New sentence 
added to mandate 
collection of AE 
information from 
subjects for up to 5 
years from the end 
of study 
Section 12.2.4 
Reporting of 
Serious Adverse 
Events and DLTs 
Page 51-52 
 
 
 
 
 
 
All cases that are fatal or 
life-threatening will be 
reported no later than 7 
days after the sponsor 
received the initial report 
from the Investigator. 
The sponsor may unmask any SAE 
reports that are serious, unexpected, 
and related to the study drug, as 
required, in accordance with safety 
reporting guidance and regulations. 
 
All cases that are fatal or life-
threatening will be reported 
immediately after the sponsor 
receives the initial report from the 
Investigator.   
Added language 
regarding 
unmasking per 
GCPs 
 
 
Shortened window 
for reporting SAEs 
per regional 
regulators 
Section 12.2.5  
Procedures for 
Unmasking 
Page 53 
Procedures for 
Unmasking 
The Investigator has the 
ability to unmask an 
individual subject’s 
treatment assignment, but 
this capability is restricted 
to medical emergencies in 
which knowledge of the 
subject’s treatment is 
critical to the 
Investigator’s ability to 
treat the subject. 
In such a case, the 
Investigator must first 
attempt to contact the 
Medical Monitor or 
backup to discuss the 
rationale for unmasking. 
If the Investigator 
determines that the 
conditions above are met, 
then s/he unmasks the 
Procedures for Unmasking 
The Investigator has the ability to 
unmask an individual subject’s 
treatment assignment, in order to 
provide emergency treatment. 
Unmasking is appropriate when 
knowledge of the subject’s dose 
would affect the medical 
management of the subject. 
If the Investigator determines 
unmasking is required, then s/he 
unmasks the subject through the 
Electronic Data Capture (EDC) 
system, files the resulting 
confirmation in a restricted file 
until the end of the study, and 
notifies the Medical Monitor within 
24 hours that the subject’s 
treatment assignment has been 
unmasked.  The Investigator will 
not communicate the treatment 
assignment to the Medical Monitor 
or to any sponsor or study team 
New section added 
per GCPs 
regarding 
unmasking 
procedures 
 
Changes to the 
unmasking 
procedure have 
been added to 
align more closely 
to GCP guidelines 
in Version 7.1 to 
Version 8.0. 

AAV8-RPGR 
 
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subject through the 
Electronic Data Capture 
(EDC) system, files the 
resulting confirmation in 
a restricted file until the 
end of the study, and 
notifies the Medical 
Monitor within 24 hours 
that the subject’s 
treatment assignment has 
been unmasked.  The 
Investigator will not 
communicate the 
treatment assignment to 
the Medical Monitor or to 
any sponsor or study team 
staff; nor should the 
treatment assignment be 
communicated to site staff 
other than those 
personnel who require 
that knowledge in order to 
treat the subject. 
The Investigator will 
ensure that the rationale, 
date, and time of 
unmasking is noted in the 
subject’s source 
documentation, but not 
the treatment assignment.  
The medical emergency 
that necessitated 
unmasking must also be 
recorded in the source 
documentation and the 
case report form per 
standard study 
procedures. 
staff; nor should the treatment 
assignment be communicated to site 
staff other than those personnel 
who require that knowledge in 
order to treat the subject. 
The Investigator will ensure that 
the rationale, date, and time of 
unmasking is noted in the subject’s 
source documentation, but not the 
treatment assignment.  The medical 
emergency that necessitated 
unmasking must also be recorded 
in the source documentation and 
the case report form per standard 
study procedures. 
Section 13.1  
Sample Size 
Page 56 
A sample size of 30 
subjects at the MTD dose 
ensures that events with an 
incidence ≥10% will be 
identified with a 95% 
probability.   
Due to the nature of the study design 
of Part I, no formal sample size 
computation was performed. 
In Part II, A a sample size of 45 
subjects, 15 in each of 3 groups 
(high-dose, low-dose and untreated), 
ensures 80% power at 0.05 
significance level assuming that the 
treated arm has 50% probability of 
achieving ≥7 dB improvement at ≥5 
loci at Month 3 vs. 5% in the 
untreated control arm. 
Specified Part I and 
Part II sample size 
rationale 
 
 

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Section 13.3.1 
Safety Analysis Set 
Page 56 
 
The Safety Analysis Set will consist 
of all subjects who receive study 
treatment (vitrectomy/AAV8-
RPGR) in Part I, and all subjects that 
are randomized in Part II. 
 
Section 13.3.2 Full 
Analysis Set 
Page 56 
The Full Analysis Set will 
include all subjects for 
whom data of at least 1 
post baseline efficacy 
assessment is available in 
at least one eye. 
The Full Analysis Set will include 
all subjects for whom data of at least 
1 post baseline efficacy assessment 
is available in the study eye. 
 
Section 13.4 
Descriptive 
Statistics 
Page 56 
 
No formal statistical comparison 
will be performed in Part I, and 
statistical tests will be conducted for 
the efficacy endpoints in Part II. 
 
Summaries will be 
generated by dose and 
overall, in Part I and, by 
group (MTD dose, and 
low-dose) in Part II. 
Summaries will be generated by 
dose and overall, in Part I and, by 
group (high-dose, low-dose, 
untreated) in Part II. 
Included untreated 
arm 
Section 13.5 
Demographics and 
Baseline 
Characteristics 
Page 57 
 
Demographics and baseline ocular 
characteristics will be summarised 
for the safety analysis set and the 
full analysis set for Part I and Part II 
separately. 
 
Section 13.6 
Efficacy Analyses 
Page 57 
Efficacy assessments are 
ocular in nature and 
therefore will be tabulated 
by eye (Study Eye and 
Fellow Eye).  Efficacy 
data will be summarised 
using descriptive statistics 
(described in Section 
13.4).  
Change from baseline in 
BCVA will be tabulated 
by visit and by eye. 
Efficacy assessments are ocular in 
nature and therefore will be 
tabulated by eye (Study Eye and 
Fellow Eye).  Efficacy data will be 
summarised using descriptive 
statistics (described in Section 13.4). 
This will be done for each cohort in 
Part I, and each arm in Part II. 
Improvement in retinal sensitivity 
and change from baseline in retinal 
sensitivity will be tabulated by visit 
and by eye in each Part, and be 
compared between the randomized 
groups in Part II by visit for the 
study eye. 
 
Section 13.6.1 
Multiplicity 
Adjustment 
Page 57 
Alpha adjustment is not 
applicable in this 
exploratory Phase 1/2 
study study. 
No multiplicity adjustment is 
planned in the study. Part I is the 
dose-escalation to identify the MTD 
based on the evaluation of benefit 
and risk without any formal 
statistical comparisons, and 
therefore no multiplicity adjustment 
is needed. In Part II, the analysis at 3 
months for the primary efficacy 
Specifies Part I and 
Part II multiplicity 
adjustment 
requirements 

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endpoint will determine whether the 
study is positive or not. Each dose 
will be compared with the untreated 
control separately by Fisher’s Exact 
Test at 0.05 level (two-sided).  
Section 13.8 
Interim Analyses 
Page 58 
In Part II, secondary 
endpoints will be analysed 
at 3, 6, 12, 18 and 24 
months with masking to 
treatment dose maintained. 
In Part II, the analysis after all 
subjects complete 3-month visit will 
evaluate the primary efficacy 
endpoint, and hence is not an interim 
analysis. The personnel who are 
involved in daily operation will 
continued to be masked of the 
treatment information until study 
completion to minimize any 
operational bias.  Additional analysis 
and a final analysis will be 
conducted for regulatory 
interactions. 
 
Section 14.1 
Informed Consent 
Page 59 
 
This is an assessor-masked study. 
All subjects will be informed at the 
time of randomisation whether they 
have been randomised to the AAV8-
RPGR or Control group. However, 
subjects in the AAV8-RPGR 
treatment groups will be masked to 
the assigned dose. 
Masking and 
randomization 
information have 
been added 
Section 15.2  
Data Handling and 
Records 
Management 
Page 61 
(by KCT Data). 
(by KCT Data). 
 
Removes 
specification for 
KCT Data 
Section 15.4  
Time and Schedule 
of the Study 
Page 62 
The expected overall study 
duration is 36 months. 
Part I includes 24 months of follow-
up for each subject enrolled and 
treated.  Part II includes 12 months 
of follow-up for each subject 
enrolled and treated. 
Duration changed 
to 24 months for 
overall study 
duration of Part 1. 
This has been 
corrected to define 
the actual duration 
per subject and not 
the estimated 
duration to last 
patient last visit. 
Part II is defined 
similarly, i.e., with 
12 months of 
follow-up for each 
subject.  

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Section 17.1 
Schedule of Study 
Procedures  
Page 68-71 
 
 
• Changes reflect 
changes in 
assessments 
detailed above 
under individual 
visits  
• Abbreviations 
updated 
• Footnotes 
updated 
Section 17.1 
Schedule of Study 
Procedures 
Page 68-71 
a. 
 Subjects will 
take 1 mg/kg/day 
prednisone/prednisolone 
for a total of 10 days 
(beginning 2 days before 
the vector injection, on the 
day of injection, and then 
for 7 days); followed by 
0.5 mg/kg/day for 7 days; 
0.25 mg/kg/day for 2 days; 
and 0.125 mg/kg/day for 2 
days (21 days in total). 
Footnotes 
Removed details on 
steroid regimen. 
This information 
can be found in 
body of protocol. 
Section 17.1 Schedule of Study Procedures  
Table 2, Pages 68-71 
Visit Number 
 
Visit 2e, Visit 3e, Visit 4e 
Added footnote to 
Visits 2-4 to clarify 
telephone call 
procedure 
Safety blood 
samples 
Samplese 
Samplesf 
Updated footnote 
reference 
RPGR mutation 
screen 
screenf 
Screeng 
Updated footnote 
reference 
Full ophthalmic 
examination 
examinationg 
examinationh 
Updated footnote 
reference 
Surgical 
procedure/dosing 
Dosingh 
Dosingi 
Updated footnote 
reference 
Dispensation of oral 
steroids 
Dispensation of oral steroidsi 
Dispensation of oral steroidsj 
Updated footnote 
reference 
EDTRS BCVA 
BCVAj 
BCVAk 
Updated footnote 
reference 

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LLVA 
X 
 
Deleted LLVA 
procedure at 
Visit  5.9, 
procedure not done. 
Fundus 
autofluorescence 
 
X 
Added Fundus 
autofluorescence to 
Visit 5 in table  
MAIA 
Microperimetry 
Microperimetryl 
Microperimetrym 
Updated footnote 
reference 
Fundus 
photography 
X 
 
Deleted Fundus 
photography from 
Visit 7, procedure 
not done 
Visual fields 
Visual fields (Octopus 900 in 
Part II)m 
Visual fields (Octopus 900 in Part 
II)n 
Updated footnote 
reference 
X 
X 
Added Visual 
Fields to Visit 6, 
deleted Visual 
Fields from Visit 
10 
 
 
 
 
 
 
 
 
 
 
 
Viral shedding 
sheddingn 
sheddingo 
Updated footnote 
reference 
Contrast sensitivity 
X 
 
Removed 
procedure from 
Visit 10 
Immunogenicity 
sampling 
samplingo 
samplingp 
Updated footnote 
reference 

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Xn 
Xp 
Updated footnote 
reference 
AE, SAE 
monitoring 
monitoringp 
monitoringq 
Updated footnote 
reference 
Corticosteriod 
compliance review 
 
reviewr 
Added footnote to 
clarify 
corticosteroid 
procedure 
Randomisation 
Randomisationq 
Randomisations 
Updated footnote 
reference 
 
 
 
 
 
Footnote d 
 
if clinically feasible 
Added to clarify 
assessment 
procedure 
Footnote e 
 
e.Visits 2, 3, and 4 will be a 
telephone call only for subjects 
randomized to the control, 
untreated group. AE/SAE 
monitoring and concomitant 
medication review will be 
assessed during the call. 
Added to clarify 
telephone call at 
Visits 2,3 and 4 
Footnote j 
 
in treated groups 
Clarified subjects 
Footnote k 
To facilitate the additional 
BCVA measures this visit 
should be conducted over 2 
days, with BCVA measured 
twice on Day 1 and once on 
Day 2 (prior to pupil 
dilation). All 3 BCVA values 
must be recorded in the 
eCRF. The highest score will 
be used to define subject 
eligibility. 
 
Moved text to end 
of footnote  
 
In Part II subjects, If … 
Clarified subjects 

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For all subjects who require 
triplicate BCVA testing, to 
facilitate the additional BCVA 
measures, this visit should be 
conducted over 2 days, with 
BCVA measured twice on Day 1 
and once on Day 2 (prior to pupil 
dilation). All 3 BCVA values 
must be recorded in the eCRF. At 
screening, The highest score will 
be used to define subject 
eligibility. 
Text moved from 
beginning of 
footnote 
Footnote m 
Triplicate at every visit for 
Part II subjects only. Part I s 
Subjects perform triplicate 
microperimetry only at baseline.  
Microperimetry should be 
conducted at unscheduled visits, 
if clinically feasible. 
 
Footnote q 
Non-serious AEs will be 
collected from Visit 2 
through Visit 10 (or ET Visit 
if applicable) 
AEs/SAEs will be collected from 
the time the subject provides 
written informed consent/assent 
through Visit 10 (or ET Visit if 
applicable).  
Added AEs to 
footnote and 
deleted collection 
of non-serious AEs 
Footnote r 
 
Corticosteroid review is 
applicable only for treated 
subjects. 
Footnote was 
added to clarify 
subjects for review 
Footnote t 
 
, and only 
Added to clarify 
procedure 
Footnotes f-j 
e., f., g., h., i., j., k., l., m., n., 
o., p., q., r., s. 
f., g., h., i., j., k., l., m., n., o., p., 
q., r., s., t. 
Updated footnote 
labels 
 

AAV8-RPGR 
 
Version 7 
Summary of Changes: Protocol: NSR-RPGR-01 
 
16 NOV 2018 
 
CONFIDENTIAL 
Page 1 of 37 
 
SUMMARY OF CHANGES FOR CLINICAL STUDY PROTOCOL  
NSR-RPGR-01  
 
AAV8-RPGR 
 
A Dose Escalation (Phase 1), and Dose Expansion (Phase 2/3) Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa GTPase Regulator (RPGR) 
Indication: 
X-Linked Retinitis Pigmentosa 
Study Phase: 
1/2/3 
Sponsor: 
NightstaRx Ltd 
2nd Floor 
10 Midford Place 
London W1T 5BJ, UK 
Telephone:  +44 (0) 020 7062 2777 
Summary of Changes: 
Protocol Version 7.0 
16 NOV 2018 
CONFIDENTIALITY STATEMENT 
This protocol is the property of NightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. 
Persons to whom the information is disclosed must be informed that the information is 
CONFIDENTIAL and may not be further disclosed by them. 
 
 

AAV8-RPGR 
 
Version 7 
Summary of Changes: Protocol: NSR-RPGR-01 
 
16 NOV 2018 
 
CONFIDENTIAL 
Page 3 of 37 
 
Overview / Rationale: Changes to the Part II Dose-Expansion Phase of the Study 
This protocol amendment changes the doses to be expanded in Part II from the “MTD and 3-dose 
levels lower than MTD” to dose 3 and dose 5. Rationale for this change was provided by the 
DMC at the October 2018 meeting. Although no DLTs have been identified through cohort 6 
treated with the highest dose, and therefore a true MTD has not been identified in this dose-
escalation, the committee recommended to expand dose 5 and dose 3, as the doses most likely to 
define safety and efficacy of AAV8-RPGR. In addition, regulatory agencies have recommended 
adding a third untreated arm to better establish efficacy and safety of the gene therapy.  Thus  the 
subjects will be randomized in a 1:1:1 allocation, with double masking to dose in the treated 
arms, and masked assessments of efficacy. 
The study duration has been shortened to 12 months of follow-up for Part II dose-expansion 
because a long-term follow-up study will be initiated to continue follow-up of all AAV8-RPGR 
subjects from 12 months to out to 5 years. Phase 1 subjects will still be followed for 24 months, 
and then also invited to participate in the long-term study.  
The endpoints and inclusion criteria are now separated by study Part to improve clarity.  
An efficacy endpoint, microperimetry at 3 months, has been added to Part II based on early 
efficacy signals observed during dose-escalation. Related to this, an inclusion range for 
microperimetry has been added to Part II in order to assure the inclusion of subjects with 
modifiable disease and to avoid inclusion of those with microperimetry values subject to ceiling 
effects.   
Additionally, to further our understanding of the effects of AAV8-RPGR, assessments of 
 
 
, and quality of life questionnaires have been added, the former two only in sites with 
the available technology. Some assessments (reading test, color vision, and full-field threshold 
sensitivity [FST]) have been removed from the study assessments due to the excessive burden of 
study visits on the subjects, and the limited value of these assessments in understanding both the 
disease and the effects of the drug.  
To improve safety and to prevent potential inflammatory response to therapy, the steroid regimen 
has been modified.  A standardized adult starting dose of 60 mg has been selected (rather than 
the previous 1mg/kg starting dose) and the taper has been lengthened to include coverage out to 
approximately 2 months. A 2-month visit has been added to assess the subjects at the end of the 
steroid therapy.  
Information on the procedures related to unmasking has been added to comply with Good 
Clinical practices. Serious adverse event reporting has also been changed to immediately instead 
of within 7 days, per regional recommendations. 
Page numbers on the following table of changes refer to the tracked changes version of the 
protocol amendment. 
 
 

AAV8-RPGR 
 
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SUMMARY OF CHANGES  
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Version 7.0, 16 NOV 2018 2018 
Section, Page 
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Title Page 
A Dose Escalation, 
Phase 1/2 Clinical Trial 
of Retinal Gene Therapy 
for X-linked Retinitis 
Pigmentosa Using an 
Adeno-Associated Viral 
Vector (AAV8) Encoding 
Retinitis Pigmentosa 
GTPase Regulator 
(RPGR) 
A Dose Escalation (Phase 1), and 
Dose-Expansion (Phase 2/3) 
Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis 
Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) 
Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
Added to title the 
dose-expansion and 
phase of the study 
has been specified 
for dose escalation 
to be Phase 1 and 
for dose expansion, 
to be Phase 2/3 
Title Page, 
Pages 1, 5, 6, 22 
 
STUDY PHASE  1/2/3 
Added Phase 3 to 
Study Phase 
Sponsor.   
Page 1 
Wellcome Gibbs 
Building, 215 Euston 
Road 
London NW1 2BE, UK 
207 611 2077 
 
2nd Floor 
10 Midford Place 
London W1T 5BJ UK 
020 7062 2777 
Change of address 
and telephone 
Sponsor Approval.   
Page 2 
 
 
, MD 
 
 
Personnel change 
Contact 
Information.  
Pages 4-5 
 
Rx Ltdr 
Wellcome Gibbs Building, 
Euston Road 
London NW1 2BE, UK 
+44 (0) 207 611 2034 
 
The contact page 
within the protocol 
now includes only 
the 
pharmacovigilance 
contact and the 
responsible CRO. 
The complete study 
contact list will be 
included in the 
study manual. 
The safety email 
remains the same 
and is listed. 
 
NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
+44 (0) 207 611 2193 
 
, MD 
NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
 
 
 
Email: 
 
 
Change in 
personnel and 
contact information 
Contract Research 
Organization 
 
 UK 
 
 
 
 
 
 
 UK 
New address and 
phone  

AAV8-RPGR 
 
Version 7 
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NightstaRx Ltd 
Wellcome Gibbs Building, 
215 Euston Road 
London NW1 2BE, UK 
781-457-+44 (0) 207 611 
2271 
 
The contact sheet 
within the protocol 
now includes only 
the 
pharmacovigilance 
contact and the 
responsible CRO. 
The complete study 
contact list will be 
included in the 
study manual. 
The safety email 
remains the same 
and is listed. 
81 Hatrwell Avenue,  
Suite 100 
Lexington, MA 02421 
  
Synopsis 
Study Period 
(years) 
Page 5 
36 months 
Part I: 24 months 
Part II: 12 months 
Duration of study 
corrected from 
estimate last 
patient, last visit to 
actual duration for 
each subject in Part 
I 
Synopsis   
Endpoints 
Page 5 
The primary safety 
endpoint is incidence of 
dose-limiting toxicities 
(DLTs) and treatment-
emergent adverse events 
(TEAEs) over a 24-month 
period. 
Endpoints 
Part I 
Primary Endpoints:  
The primary safety endpoints are the 
incidence of dose-limiting toxicities 
(DLTs), and treatment-emergent 
adverse events (TEAEs) over a 24-
month period.   
Secondary and Exploratory 
Endpoints: 
• Change from baseline in 
microperimetry at 3, 6, 12, 18 and 
24 months 
• Change from baseline in best-
corrected visual acuity (BCVA) at 
3, 6, 12, 18, and 24 months 
• Change from baseline in spectral 
domain optical coherence 
tomography (SD-OCT) at 3, 6,12, 
18 and 24 months 
• Change from baseline in 
autofluorescence at 3, 6, 12, 18 
and 24 months 
• Change from baseline in other 
anatomical and functional 
Separated out Part I 

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outcomes at 3, 6, 12 months, 18 
and 24 months 
Synopsis.   
Endpoints 
Pages 5-6 
 
Part II 
Primary Efficacy Endpoint: 
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
Safety Endpoint: 
The safety endpoint is incidence of 
TEAEs over a 12-month period. 
Separated out Part 
II  
Synopsis.   
Endpoints 
Pages 5-6 
• Change from baseline 
in microperimetry at 3, 
6, 9, 12 18 and 24 
months 
• Change from baseline 
in best-corrected visual 
acuity (BCVA) at 3, 6, 
12 18 and 24 months 
• Change from baseline 
in SD-OCT at 3, 6, 12 
18 and 24 months 
• Change from baseline 
in autofluorescence at 
3, 6, 12, 18 and 24 
months 
Secondary Endpoints: 
• 
Change from baseline in 
microperimetry at 1, 6, 9, and 
12 months 
• 
Change from baseline in best-
corrected visual acuity (BCVA) 
at 3, 6, and 12 months 
• 
Change from baseline in SD-
OCT at 3, 6, and 12 months 
• 
Change from baseline in 
autofluorescence at 3, 6, and 12 
months 
• 
Change from baseline in visual 
field assessed by Octopus 900 
at 3, 6, and 12 months 
Updated Part II 
endpoints 
• 
Change from baseline 
in other anatomical 
and functional 
outcomes at 3, 6, 12, 
18 and 24 months 
Exploratory Endpoints: 
 
• 
 
• 
Change from baseline in 
adaptive-optics (AO)-OCT at 6 
and 12 months 
• 
 
 
• 
Change from baseline in other 
anatomical and functional 
outcomes at 3, 6, and 12 months 
• Updated Part II 
endpoints 
Synopsis.   
Study Design  
Pages 6-8 
The study will be 
conducted in two parts: 
Part I is a dose escalation 
study, Part II is a 
Maximum Tolerated Dose 
(MTD) expansion study 
(as determined in Part I) 
This is a Phase 1/2/3… 
Part I is a dose-selection study; Part 
II is a dose-expansion study, with 2 
doses (2.5 × 10^11 gp [high dose], 5 
× 10^10 gp [low dose]) selected 
from Part I based on a benefit/risk 
assessment, and a third untreated 
Study design 
description updated 
to include Part I 
and Part II. Part II 
now defines doses 
as high and low 
doses and not as 

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group to allow for a controlled 
comparison of efficacy and safety.   
MTD since the 
chosen high dose to 
be expanded has 
not been defined as 
MTD. 
The study will consist 
of visits over a 24-month 
evaluation period. 
 
At the 
Screening/Baseline Visit, 
each subject will be 
assessed for eligibility of 
both eyes. Only 1 eye 
will receive treatment 
(the “study eye”), and the 
untreated eye will be 
designated as the “fellow 
eye”.   
Part I consists of 12 visits over a 24-
month evaluation period. 
 
Part II consists of 10 visits over a 
12-month evaluation period. Only 1 
eye will be randomized (the “study 
eye”), and the other eye will be 
designated as the “fellow eye”.  
Selection of the “study eye” will be 
made on clinical grounds prior to 
randomization and will generally be 
the worse eye affected. 
Differentiates the 
visit number and 
duration for Parts I 
and II 
 
Subjects in the untreated control 
group will receive study-visit 
telephone calls to monitor 
AEs/SAEs and review concomitant 
medications on Visit 2 (Day 0) and 
on Visits 3 and 4 (post-operative 
Days 1 and 7). 
Information on 
conduct for 
untreated control 
subjects has been 
added regarding the 
surgery day and 
post-operative 
Days 1 and 7.  
To minimise 
inflammation resulting 
from surgery and/or 
vector/transgene, all 
subjects will be given a 
21-day course of oral 
corticosteroid (e.g., 
prednisolone/prednisone) 
that will start 2 days 
before the planned date 
of surgery. 
To minimise inflammation resulting 
from surgery and/or 
vector/transgene, in Part I, all 
subjects will be given a 21-day 
course of oral corticosteroid (e.g., 
prednisolone/prednisone) that will 
start 2 days before the planned date 
of surgery. 
In Part II, all subjects will be treated 
at the time of surgery with up to 1 
mL of triamcinolone (40 mg/mL), 
placed behind the globe via a deep 
sub-Tenon approach.  All subjects 
will also be given a 9-week course 
of oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, 
followed by 6 weeks of tapering 
doses. The dose regimen is adjusted 
for pediatric subjects treated in Part 
II (see Section 9.8).   
To improve safety 
and to prevent 
potential 
inflammatory 
response to 
therapy, the steroid 
regimen has been 
modified.  A 
standardized adult 
starting dose of 60 
mg has been 
selected (rather 
than the previous 
1mg/kg starting 
dose) and the taper 
has been 
lengthened to 
include coverage 
out to 
approximately 2 
months. A 2-month 
visit has been 
added to assess the 

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subjects at the end 
of the steroid 
therapy. 
 
At study completion, Part I subjects 
will be invited to participate in a 
separate long-term follow-up study 
that will collect efficacy and safety 
data up to 5 years from surgery. 
Added the 
extension of 
follow-up for Part I 
subjects 
Part II: MTD Expansion 
Study 
 
Part II: Dose Expansion  
In Part II, 45 subjects will be 
randomized 1:1:1 to a high-dose 
(2.5 × 10^11 gp), a low-dose 
(5 × 10^10 gp), and a third untreated 
group to allow for a controlled 
comparison of efficacy and safety. 
Study data will be collected for both 
eyes of each subject. Since treatment 
requires an invasive surgical 
procedure under general anaesthesia, 
the sponsor, investigator and the 
subject will be unmasked to the 
study procedure (i.e., vitrectomy and 
sub-retinal injection), however 
within the treated groups, the 
sponsor, investigator and subject 
will be masked to the assigned dose. 
To further minimise potential bias of 
the treated and non-treated eye 
evaluations, all subjective 
ophthalmic assessments at the 
Screening/Baseline Visit (Visit 1) 
and from Month 1 (Visit 5) onwards 
will be conducted by a masked 
assessor. 
Clarified 
randomization for 
Part II Dose 
Expansion as 3-
armed study with 
untreated arm 
added, per general 
rationale above.  
Added language 
explaining the 
assessor masking. 
Once the MTD has been 
identified, up to 45 
additional subjects will be 
randomized, in a 2:1 
allocation ratio.  Subjects 
will receive AAV8-RPGR 
either at the MTD (MTD 
cohort), or at a low dose 
(active-control cohort), 
three dose-levels below 
the MTD (e.g., low dose = 
5 x 1010 gp if MTD = 
5x1011 gp).  Part II of the 
study will be randomized 
and double-masked to the 
assigned dose, and open-
Subjects, sponsor, investigators and 
clinical assessors will be masked to 
the assigned dose.   
All Part II subjects will be followed 
for 12 months with the pre-specified 
visit schedule.  At study completion, 
Part II subjects will be invited to 
participate in a separate long-term 
follow-up study that will collect 
efficacy and safety data from Month 
12 through 5 years from surgery. 
Clarified 
randomization for 
Part II Dose 
Expansion as 3-
armed study with 
untreated arm 
added, per general 
rationale above. 

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label to the treatment 
administration. 
Synopsis 
Inclusion Criteria  
Page 9 
1. Subject / parent (if 
applicable) is willing 
and able to give 
informed consent for 
participation in the 
study 
 
Part I is only in 
adults so removed 
the language for 
minors 
Synopsis  
Inclusion Criteria 
Page 9 
2. Are male and able to 
comply and adequately 
perform all study 
assessments 
Part I:≥18 years of age 
Part II: ≥10 years of age 
Part I 
Are male, ≥18 years of age, and able 
to comply and adequately perform 
all study assessments. 
Clarified age 
inclusion criterion 
for Part I;  
separated Part I and 
Part II inclusion 
criteria to add 
clarity for 
investigators; 
Synopsis 
Inclusion Criteria 
Page 9 
5. BCVA in both eyes that 
meets the following 
criteria, based on the 
cohort level: 
Cohort 4-6 and study 
Part II: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better 
than or equal to 6/60 
or 20/200 Snellen 
acuity) 
 
5. BCVA in both eyes that meets the 
following criteria, based on the 
cohort level: 
Cohort 4-6: better than or 
equal to BCVA of 34 
ETDRS letters (equivalent 
to better than or equal to 
6/60 or 20/200 Snellen 
acuity) 
Removed Part II 
BCVA inclusion 
criterion because 
inclusion criteria 
are now 
separated for Part 
II to improve 
clarity 
Synopsis 
Inclusion Criteria 
Part II 
Pages 9-10 
 
Part II 
Inclusion Criteria 
1. Subject / parent (if applicable) is 
willing and able to provide informed 
consent for participation in the study 
2. Are male, ≥10 years of age, and 
able to comply and adequately 
perform all study assessments 
3. Have a genetically confirmed 
diagnosis of XLRP (with RPGR 
mutation) 
4. Have active disease clinically 
visible within the macular region in 
the study eye and defined as follows: 
 ellipsoid zone (EZ) on SD-OCT at 
screening must be measurable, 
and within the nasal and temporal 
border of any B-scan, and not be 
visible on the most inferior and 
superior B-scan 
• Added section for 
Part II inclusion 
criteria to clarify 
the differences 
between Parts I 
and II; 
• EZ zone must be 
measurable on 
screening in the 
study eye 
• BCVA is same for 
all subjects in Part 
II (no cohort 
differences); 
specifies criterion 
is for study eye 
only 
• Added mean total 
retinal sensitivity 
range in the study 

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5.Have a BCVA in the study eye 
that meets the following criteria: 
•Better than or equal to BCVA of 34 
ETDRS letters (equivalent to better 
than or equal to 6/60 or 20/200 
Snellen acuity). 
6. Mean total retinal sensitivity in 
the study eye as assessed by 
microperimetry ≥0.1 dB and ≤8 dB  
eye to ensure that 
subjects have 
modifiable 
microperimetry 
not subject to 
ceiling effects 
Synopsis, 
Exclusion Criteria 
Page 10 
 
Exclusion Criteria: Parts I and II 
Specifies that 
exclusion criteria 
are the same for 
both parts 
Synopsis 
Test Product, 
Dosage, and Mode 
of Administration 
Page 10 
 
Part I, Dose Escalation, Phase 1: 
All subjects will undergo vitrectomy 
and receive a single sub-retinal 
injection of AAV8-RPGR. Subjects 
will be assigned to 1 of the 
following AAV8-RPGR dose levels: 
5 × 10^9 gp, 1 × 10^10 gp, 
5 × 10^10 gp, 1 × 10^11 gp, 
2.5 × 10^11 gp, or 5 × 10^11 gp. 
 
Part II, Dose Expansion, Phase 2/3: 
Subjects will be assigned to 1 of the 
following: high-dose 
(2.5 × 10^11 gp), low-dose 
(5 × 10^10 gp), or an untreated 
control arm. 
Separated out Parts 
I and II for 
improved clarity 
Synopsis.   
Reference Therapy 
Page 10 
In Part I, no Reference 
therapies will be 
administered. In Part II, a 
high dose and a low dose 
of AAV8-RPGR (active-
control cohort) the 
concentration of which 
will be three  dose-levels 
from MTD. 
In Part I, no Reference therapies will 
be administered. In Part II, 2 doses 
of AAV8-RPGR will be compared: a 
high-dose (2.5 × 10^11 gp) and a 
low-dose (5 × 10^10 gp).  An 
untreated control arm will also be 
added. 
Added comparator 
dosing and 
untreated arm to 
reference therapy 
Synopsis.   
Criteria for 
Evaluation 
Page 10 
Efficacy: The efficacy 
evaluation will be based 
on BCVA, SD-OCT, 
fundus autofluorescence, 
visual fields, 
microperimetry, contrast 
sensitivity, low luminance 
VA, full field stimulus 
threshold test, colour 
vision and reading test. 
Efficacy: The efficacy evaluation 
will be based on microperimetry 
(MAIA), BCVA, SD-OCT,
, fundus 
autofluorescence, visual fields 
(Octopus 900 specified in Part II 
only), contrast sensitivity, LLVA, 
 
 
Efficacy evaluation 
updated to include 
MAIA 
microperimetry; for 
Part II only, 
, 
 and 
 have been 
added; specifies 
Octopus 900 for 
visual field only in 
Part II 

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Synopsis  
Statistical 
Methodology 
Page 11 
The primary objective is 
to evaluate… 
The primary objective of Part I is to 
evaluate… 
Differentiates Part I 
objective from Part 
II objective 
 
The primary objective of Part II is 
to evaluate the efficacy and safety 
of AAV8-RPGR in an expanded 
population of subjects. 
Differentiates Part I 
objective from Part 
II objective 
A sample size of 30 
subjects at the MTD dose 
ensures that events with 
an incidence ≥10% will 
be identified with a 95% 
probability. 
In Part II, subjects will be 
randomized 1:1:1 to the 2 doses of 
AAV8-RPGR: 2.5 × 10^11 gp and 
5 × 10^10 gp or an untreated 
control group.   
Randomization 
clarification for 
Part II, with 
addition of 
untreated control 
group 
 
Fisher’s exact test will be utilized 
for the comparisons of binary 
endpoints, and T-test will be 
employed for the comparisons of 
continuous endpoints. 
Statistical methods 
to include Fisher’s 
exact test and T-
tests 
Section 6  
Study Objectives 
and Endpoints 
Page 22 
The primary safety 
endpoint is incidence of 
dose-limiting toxicities 
(DLTs) and treatment-
emergent adverse events 
(TEAEs) over a 24-month 
period. 
Endpoints 
Part I 
Primary Endpoints:  
The primary safety endpoints are the 
incidence of dose-limiting toxicities 
(DLTs), and treatment-emergent 
adverse events (TEAEs) over a 24-
month period.   
Secondary and Exploratory 
Endpoints: 
• Change from baseline in 
microperimetry at 3, 6, 12, 18 and 
24 months 
• Change from baseline in best-
corrected visual acuity (BCVA) at 
3, 6, 12, 18, and 24 months 
• Change from baseline in spectral 
domain optical coherence 
tomography (SD-OCT) at 3, 6,12, 
18 and 24 months 
• Change from baseline in 
autofluorescence at 3, 6, 12, 18 
and 24 months 
• Change from baseline in other 
anatomical and functional 
outcomes at 3, 6, 12 months, 18 
and 24 months 
Separated out Part I 
Section 6.2.2 Study 
Objectives and 
Endpoints 
 
Part II 
Primary Efficacy Endpoint: 
Separated out Part 
II  

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Page 22 
The primary efficacy endpoint is 
improvement from Baseline in 
microperimetry at 3 months. 
Safety Endpoint: 
The safety endpoint is incidence of 
TEAEs over a 12-month period. 
Section 6.2.2.3  
Study Objectives 
and Endpoints 
Page 19-20 
• Change from baseline 
in microperimetry at 3, 
6, 9, 12 18 and 24 
months 
• Change from baseline 
in best-corrected visual 
acuity (BCVA) at 3, 6, 
12 18 and 24 months 
• Change from baseline 
in SD-OCT at 3, 6, 12 
18 and 24 months 
• Change from baseline 
in autofluorescence at 
3, 6, 12, 18 and 24 
months 
Secondary Endpoints: 
• 
Change from baseline in 
microperimetry at 1, 6, 9, and 
12 months 
• 
Change from baseline in best-
corrected visual acuity (BCVA) 
at 3, 6, and 12 months 
• 
Change from baseline in SD-
OCT at 3, 6, and 12 months 
• 
Change from baseline in 
autofluorescence at 3, 6, and 12 
months 
• 
Change from baseline in visual 
field assessed by Octopus 900 
at 3, 6, and 12 months 
Updated Part II 
endpoints 
• 
 
 
 
 
Exploratory Endpoints: 
 
 
 
 
 
 
 
 
 
 
 
Updated Part II 
endpoints 
Section 7.1.  
Overall Design 
Pages 24-25 
-   Part II is a Maximum 
Tolerated Dose (MTD) 
expansion study (as 
determined in Part I). 
This is a Phase 1/2/3… 
 
The study will be conducted in two 
parts: Part I is a dose escalation 
study, Part II is a dose-expansion 
study, with 2 doses selected from 
Part I based on safety and efficacy, 
and a third untreated group to allow 
Updated study 
design overview 
for Parts I and II to 
include expanded 
description of 
individual parts 

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for a controlled comparison of 
efficacy.  
Part I will identify the maximum 
tolerated dose (MTD) using a dose-
escalation scheme. Part II will 
expand 2 doses, allowing for a 
broader assessment of the safety and 
efficacy of AAV8-RPGR with a 
larger sample size, including 45 
subjects randomized 1:1:1 to the a 
high-dose, a low-dose, and an 
untreated arm.  Part I primarily 
evaluates safety, defined by 
incidence of DLTs and TEAEs over 
a 24-month period.  Phase II 
evaluates safety and efficacy, with 
inclusion of a primary efficacy 
endpoint, improvement from 
Baseline in microperimetry, 
evaluated at 3 months, and safety 
and secondary efficacy evaluated at 
1-, 6-, 9- and 12 -months post-
treatment. 
All Part II subjects treated under 
previous versions of the protocol 
will be followed for 12 months with 
the pre-specified visit schedule. 
At study completion, all subjects 
will be invited to participate in a 
separate long-term follow-up study 
that will collect efficacy and safety 
data up to 5 years from surgery. 
The study will consist of  
visits over a 24-month 
evaluation period.   
Part I consists of 12 visits over a 24-
month evaluation period.  Part II 
consists of 10 visits over a 12-month 
period 
Differentiated Part 
I and Part II visit 
number and 
duration  
 
To minimise inflammation resulting 
from surgery and/or 
vector/transgene, in Part I, all 
subjects will be given a 21-day 
course of oral corticosteroid. 
In Part II, all subjects will be treated 
at the time of surgery with up to 1 
mL of triamcinolone (40 mg/mL), 
placed behind the globe via a deep 
sub-Tenon approach.  Subjects will 
also be given a 9-week course of 
oral corticosteroid starting 3 days 
before surgery: 21 days at 60 mg, 
followed by 6 weeks of tapering 
• To improve 
safety and to 
prevent potential 
inflammatory 
response to 
therapy, the 
steroid regimen 
has been 
modified.  A 
standardized 
adult starting 
dose of 60 mg 
has been selected 

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doses. The dose regimen is adjusted 
for pediatric subjects treated in Part 
II (see Section 9.8). 
Subjects in the untreated control 
group will receive study-visit 
telephone calls to monitor 
AEs/SAEs and review concomitant 
medications on Visit 2 (Day 0) and 
on Visit 3 and 4 (post-operative 
Days 1 and 7). 
(rather than the 
previous 1mg/kg 
starting dose) 
and the taper has 
been lengthened 
to include 
coverage out to 
approximately 2 
months. A 2-
month visit has 
been added to 
assess the 
subjects at the 
end of the steroid 
therapy. 
• The treatment of 
untreated 
subjects at Visits 
2, 3 and 4 has 
been added 
The efficacy evaluation 
will be based on BCVA, 
SD-OCT, fundus 
autofluorescence, 
microperimetry, visual 
fields, contrast sensitivity, 
low luminance visual 
acuity (LLVA), full-field 
stimulus threshold test 
(FST), colour vision, and 
reading test.  Any safety 
information collected as a 
result of the efficacy 
assessments (e.g., BCVA) 
will also be used in the 
overall safety evaluation, 
as applicable. 
Subjects who develop 
cataracts may undergo 
cataract surgery if deemed 
clinically necessary; if 
surgery is performed, it 
should be carried out at 
least 4 weeks before Visit 
1 (Year 1) or Visit 11 
(Year 2). 
A subject is considered to 
have completed the study 
if he completes the Year- 
The efficacy evaluation will be 
based on microperimetry, BCVA, 
SD-OCT, fundus autofluorescence, 
visual fields (Octopus 900 specified 
in Part II only), contrast sensitivity, 
low luminance visual acuity 
(LLVA), 
 and 
 
 
 
Subjects who develop cataracts may 
undergo cataract surgery if deemed 
clinically necessary; if surgery is 
performed, it should be carried out at 
least 4 weeks before their final visit.  
A Part I subject is considered to 
have completed the study if he 
completes the Month-24 
assessments.  A Part II subject is 
considered to have completed the 
study if he completes the Month 12 
assessments.  
The end of the trial is the date the 
last subject completes his final-visit 
assessments (or early termination 
[ET] assessments in the event of 
premature discontinuation) or the 
date of last data collection if the last 
subject is lost to follow-up. 
• Clarified efficacy 
evaluations; 
added 
 
 at 
sites with 
available 
technology; 
added 
 
• All above only in 
Part II 
• Specified 
Octopus 900 
only in Part II for 
visual field 
assessment 
• Removed 
assessments that 
have caused 
unnecessary 
study burden in 
subjects and that 
have not 
provided 
valuable 
information in 
Part I 
• Differentiated 
duration in Part I 

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2 assessments.  The end of 
the trial is the date the last 
subject completes his 
Year- 2 assessments (or 
early termination [ET] 
assessments in the event of 
premature discontinuation) 
or the date of last data 
collection if the last 
subject is lost to follow-
up. 
and Part II as 
well as definition 
of study 
completion 
Section 7.1.3.   
Dose Expansion 
Page 27 
Once the MTD has been 
identified, uUp to 45 
additional subjects will be 
randomized, in a 2:1 
allocation ratio^ ^ .  
Subjects will receive 
AAV8-RPGR either at the 
MTD (MTD cohort), or at 
a low dose (active-control 
cohort), three dose-levels 
below the MTD (e.g., low 
dose = 5 5 x x 1010 gp if 
MTD = 5x1011 gp).   
Part II of the study will be 
randomized and double-
masked to the assigned 
dose, and open-label to the 
treatment administration. 
Up to 45 additional subjects will be 
randomized in a 1:1:1 allocation 
ratio to a high-dose group (2.5 × 
10^11 gp), a low-dose group (5 × 
10^10 gp), and an untreated group.   
 
Study data will be collected for both 
eyes of each subject. Since treatment 
requires an invasive surgical 
procedure under general anaesthesia, 
the sponsor, investigator and the 
subject will be unmasked to the 
study procedure (i.e., vitrectomy and 
sub-retinal injection), however 
within the treated groups, the 
sponsor, investigator and subject 
will be masked to the assigned dose. 
To further minimise potential bias of 
the treated and non-treated eye 
evaluations, all subjective 
ophthalmic assessments at the 
Screening/Baseline Visit (Visit 1) 
and from Month 1 (Visit 5) onwards 
will be conducted by a masked 
assessor. 
Part II description 
now identifies 
treatments as dose 
5 and dose 3 and 
untreated arm 
added, per general 
rationale (see 
above).  
Description of 
assessor masking 
added 
Section 7.3  
Discussion of Study 
Design and Dose 
Selection 
Page 28 
The planned sample size is 
consistent with a 3+3 
escalation scheme.  A 
prospective trial period of 
24 months is considered to 
be a sufficient period of 
time to monitor for any 
AEs related to the vector 
and/or 
transgene/administration 
procedure.   
The planned sample size in Part I is 
consistent with a 3+3 escalation 
scheme.  A prospective trial period 
of 24 months is considered to be a 
sufficient period of time to monitor 
for any AEs related to the vector 
and/or transgene/administration 
procedure.   
Specified Part I for 
dose escalation 
Section 7.3 
Discussion of Study 
Further details are 
provided in the 
Investigator’s Brochure., 
Further details are provided in the 
Investigator’s Brochure.Given 
previous experience demonstrating 
This information 
was removed as it 

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Design and Dose 
Selection 
Pages 27-30 
and a summary of the 
AAV8-RPGR doses in the 
toxicology species is 
presented in the table 
below.  The safety and 
efficacy findings from 
other pre-clinical and 
clinical studies with 
AAV8 vector for 
subretinal delivery are also 
included for comparison. 
the safety of higher subretinal doses 
of AAV8 vector 
(Vandenberghe 2011), and lacking 
safety signals at the lower range of 
doses, it should be possible to dose-
escalate to the high end of the dose 
range of AAV8-RPGR 
is redundant with 
the IB. 
The added 
language clarified 
the overall 
meaning.  
Table 1: Toxicology 
Safety Margin for Clinical 
Trials 
 
Eliminated the 
table from the 
protocol as this is 
redundant with the 
IB.  
Once the MTD has been 
identified and the safety 
and tolerability of AAV8-
RPGR is demonstrated in 
adults, subjects ≥10 year 
age will be enrolled in Part 
II of the study.  The 10-
years of age cut-off 
safeguards… 
Once Part I dose-escalation has been 
completed, and the safety and 
tolerability of AAV8-RPGR is 
demonstrated in adults, subjects ≥10 
years of age will be enrolled in Part 
II of the study.  The 10-years of age 
cut-off safeguards… 
Clarified that dose 
escalation 
completion is 
trigger to Part II 
In Part II, subjects will be 
randomized to ‘MTD 
cohort’ or the ‘active-
control  The active-control 
cohort will be three dose-
levels below the MTD. 
This assures a 1-1.5-log 
difference in dose between 
these two cohorts, and 
allows for identifying a 
dose response while 
mitigating the possibility 
of a subtherapeutic low 
dose. 
In Part II, subjects will be 
randomized to a high-dose (2.5 × 
10^11 gp), a low-dose (5 × 10^10 
gp), and an untreated group.   This 
allows for comparisons in a 
randomized and controlled fashion, 
as recommended by regulators for 
best practices in ophthalmic gene 
therapy studies (Human Gene 
Therapy for Retinal Disorders, Draft 
Guidance for Industry July 2018). 
The sponsor, investigator and the 
subject will be unmasked to the 
study procedure and treatment (i.e. 
vitrectomy and sub-retinal 
injection). However, within the 
treated groups, the sponsor, 
investigator and subject will be 
masked (i.e. double-masked) to the 
assigned dose. To further minimise 
potential bias of the treated and non-
treated eye evaluations, all 
subjective ophthalmic assessments at 
the Screening/Baseline Visit (Visit 
1) and from Month 1 (Visit 5) 
Part II description 
now identifies 
treatments as dose 
5 and dose 3 and 
untreated arm 
added, per general 
rationale (see 
above).  
 
Added description 
of masking 
procedures 

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onwards will be conducted by a 
masked assessor. 
Section 8.0 
Selection and 
Withdrawal of 
Subjects 
Page 31 
 
8.1 Part I 
Differentiating Part 
I and Part II 
inclusion criteria to 
improve clarity 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Page 31 
Subject / parent (if 
applicable) is willing and 
able to give informed 
consent for participation in 
the study 
 
• Part I is only in 
adults so removed 
the language for 
minors 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Page 31 
3. Are male and able to 
comply and adequately 
perform all study 
assessments 
Part I:≥18 years of age 
Part II: ≥10 years of age 
Part I 
Are male, ≥18 years of age, and able 
to comply and adequately perform 
all study assessments. 
Clarified age 
inclusion for Part I;  
• separated Part I 
and Part II 
inclusion to add 
clarity for 
investigators; 
Section 8.1 Part I 
Section 8.1.1  
Inclusion Criteria 
Page 31 
5. BCVA in both eyes that 
meets the following 
criteria, based on the 
cohort level: 
Cohort 4-6 and study 
Part II: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better 
than or equal to 6/60 
or 20/200 Snellen 
acuity) 
 
5. BCVA in both eyes that meets the 
following criteria, based on the 
cohort level: 
Cohort 4-6: better than or equal to 
BCVA of 34 ETDRS letters 
(equivalent to better than or equal to 
6/60 or 20/200 Snellen acuity) 
• Removed Part II 
because inclusion 
criterion is now 
separated for Part 
II to improve 
clarity 
Section 8.2  
Part II 
Section 8.2.1 
Inclusion Criteria 
Page 31 
 
Part II 
• Differentiating 
Part I and Part II 
inclusion criteria 
to improve clarity 

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Section 8.2  
Part II 
Section 8.2.1 
Inclusion Criteria 
Pages 31-32 
 
Part II 
Inclusion Criteria 
1. Subject / parent (if applicable) is 
willing and able to provide informed 
consent for participation in the study 
2. Are male, ≥10 years of age, and 
able to comply and adequately 
perform all study assessments 
3. Have a genetically confirmed 
diagnosis of XLRP (with RPGR 
mutation) 
4. Have active disease clinically 
visible within the macular region in 
the study eye and defined as follows: 
 ellipsoid zone (EZ) on SD-OCT at 
screening must be measurable, 
and within the nasal and temporal 
border of any B-scan, and not be 
visible on the most inferior and 
superior B-scan 
5.Have a BCVA in the study eye 
that meets the following criteria: 
•Better than or equal to BCVA of 34 
ETDRS letters (equivalent to better 
than or equal to 6/60 or 20/200 
Snellen acuity). 
6. Mean total retinal sensitivity in 
the study eye as assessed by 
microperimetry ≥0.1 dB and ≤8 dB  
• Added section for 
Part II inclusion 
criteria to clarify 
the differences 
between Parts I 
and II; 
• EZ zone must be 
measurable on 
screening in the 
study eye 
• BCVA is same for 
all subjects in Part 
II (no cohort 
differences); 
specifies criterion 
is for study eye 
only 
• Added mean total 
retinal sensitivity 
range in the study 
eye to ensure that 
subjects have 
modifiable 
microperimetry 
not subject to 
ceiling effects 
Section 8.3.  
Exclusion Criteria: 
Parts I and II  
Page 32 
 
Parts I and II 
To clarify that 
exclusion criteria 
are the same for 
Parts I and II 
Section 9.1 
Treatments 
Administered 
Page 34 
At the Injection Day Visit 
(Visit 2, Day 0), subjects 
will undergo vitrectomy 
and retinal detachment in 
their study eye and then 
receive a single, sub-
retinal injection of AAV8-
RPGR (See Section 9.4 for 
details). 
Part I, Dose Escalation, Phase 1: all 
subjects will undergo vitrectomy and 
retinal detachment in their study eye 
and then receive a single, sub-retinal 
injection of AAV8-RPGR (See 
Section 9.4 for details). 
Part II, Dose Expansion, Phase 2/3: 
Subjects will be assigned to 1 of the 
following: high-dose (2.5 × 10^11 
gp), low-dose (5 × 10^10 gp), or an 
untreated control arm. 
Clarified the 
treatments in Part I 
and Part II 
Section 9.3.  
Packaging, 
Labeling, 
Preparation and 
Storage 
Page 34 
The Investigational 
Medicinal Product will be 
labelled in compliance 
with regulatory standards. 
(on either the primary or 
secondary container) and 
The Investigational Medicinal 
Product (IMP) will be labelled in 
compliance with regulatory 
standards. 
Deleted label 
information. 

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include the protocol study 
number, Sponsor’s name, 
product name, titre, vial 
and lot number, expiration 
date, (IMP labellied for 
Europe only) storage 
conditions and caution 
statement. 
Section 9.4 
Vitrectomy 
Procedure and 
Injection of AAV8-
RPGR 
Pages 34-35 
 
The subretinal injection technique to 
be used in this study is similar to 
that developed in the sponsor’s 
choroideremia programme in 
Oxford… To date, over 150 subjects 
have been injected without 
complication by retinal surgeons 
using the technique described below. 
All subjects will be treated at the 
time of surgery with up to 1 mL of 
triamcinolone (40 mg/mL), placed 
behind the globe via a deep sub-
Tenon approach. 
Updated vitrectomy 
procedure 
background and 
added description 
of additional local 
steroid 
administration at 
the time of surgery 
Section 9.5 
Randomisation 
Page 36 
The dose-escalation 
portion of this study is not 
randomized. 
 
In Part II, after the study 
eye is assigned, subjects 
will be randomised a 2:1 
ratioAAV8-RPGR MTD 
or a lower dose of AAV8-
RPGR, three dose-levels 
from MTD (e.g., low dose 
= 5 x 1010 gp if MTD = 
5x1011 gp) for the active-
control cohort.   
Part I, the dose-escalation portion of 
this study, is not randomized. 
In Part II, after the study eye is 
assigned, subjects will be 
randomised to 1 of 3 groups with a 
1:1:1 allocation ratio: 1) treatment 
with AAV8-RPGR at a high dose 
(2.5 × 10^11 gp); 2) treatment with 
AAV8-RPGR at a low dose (5 × 
10^10 gp) or 3) no treatment.   
Part II 
randomization 
procedure added; 
doses identified as 
dose 5 and dose 3 
and untreated arm 
added, per 
introductory 
general rationale.  
Section 9.6.   
Study Masking 
Page 36-37 
Part II is double-masked 
(subject, surgeon, 
investigator/site team, 
sponsor will be masked to 
the assigned dose, and 
open-label with respect to 
the treatment 
administration). 
In Part II, all ophthalmic 
assessments that are conducted at the 
Screening/Baseline Visit will be 
conducted by appropriately qualified 
masked assessors.  For the 
immediate post-operative visits, 
masking of the assessors will not be 
viable as clinical signs of surgery 
will be apparent (i.e. redness, 
swelling). Therefore, unmasked 
assessors will perform all 
ophthalmic assessments at Visit 3 
(Day 1) and Visit 4 (Day 7). For 
Visit 5 (Month 1) onwards, masked 
assessors will be used, as any signs 
Clarified masking 
procedure 

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of surgery will have dissipated and it 
will not be possible clinically to 
differentiate between those subjects 
that have not undergone surgery, and 
those subjects that have undergone 
surgery and received active 
treatment. 
Subjects randomised to the untreated 
Control group will not be required to 
attend the site at Visit 2, 3 or 4. As 
the key purpose of Visit 2 is surgery, 
and Visit 3 and 4, post-operative 
safety, there is limited utility in 
Control subjects attending. 
Therefore, to limit the study burden 
for Control subjects thereby 
potentially reducing the risk of 
subject withdrawal at this stage and 
reducing the possibility of further 
unmasking due to direct contact and 
communication with fellow 
participants, Control subjects are not 
scheduled to attend the clinic for 
study visits at these times. 
In order to minimise bias further, 
masked assessors will not have 
access to the subject’s medical 
records, source documentation or 
eCRF as data entries or notation 
(such as use of peri-operative 
corticosteroid) may be sources of 
unmasking. From Visit 5 (Month 1) 
onwards, the masked assessor will 
also read a pre-written statement to 
each subject, regardless of 
randomisation, reminding them of 
the masked nature of the study, and 
to avoid any reference to prior 
surgery/non-surgery, which eye may 
have received treatment or to allude 
to any information that may unmask 
the assessor as to which group the 
subject has been assigned to.  
Furthermore, it is anticipated that a 
subset of the subjects participating in 
the trial will be active on social 
media. Following appropriate 
approval by the Independent Ethics 
Committee (IEC)/Institutional 
Review Board (IRB), the patient 
information leaflet will request that 
subjects refrain from posting any 
details of study participation on 
social media, that may unmask the 
assessors to the group the subject 
has been assigned to. This request 

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will be reiterated at subject visits by 
the investigator and within the pre-
written statement. 
Subjects randomised to the AAV8-
RPGR treatment groups, surgeons, 
the investigative team and the study 
sponsor will be masked to which 
dose of AAV8-RPGR the subject 
has been assigned to. Unmasked 
study site personnel will be assigned 
the responsibility of performing 
dilution, which will take place in a 
designated area remote from the 
investigative team to preserve 
masking of the treatment arm. 
Personnel delegated to perform the 
dilution will not be involved in any 
other aspect of the study (i.e., 
consent, safety/efficacy assessments, 
surgical procedure). 
Section 9.8 
Concomitant 
Therapy 
Pages 37-39 
 
To minimise inflammation, at the 
time of surgery, all subjects will be 
treated with a course of 
corticosteroid. 
In Part I, all subjects will also be 
prescribed a 21-day course of oral 
prednisone/prednisolone, following 
closely the 17-day protocol 
established in the Philadelphia AAV 
gene therapy clinical trial (Maguire 
et al., 2008), except allowing an 
extra 4 days for tapering the dose at 
the end of the course, i.e., 
1 mg/kg/day prednisone / 
prednisolone for a total of 10 days 
(beginning 2 days before the vector 
injection, on the day of injection, 
and then for 7 days); followed by 
0.5 mg/kg/day for 7 days; 
0.25 mg/kg/day for 2 days; and 
0.125 mg/kg/day for 2 days (21 days 
in total. 
 
In Part II, at the time of surgery, all 
subjects (adult and pediatric) will be 
treated with up to 1 mL of 
triamcinolone, 40 mg/mL solution, 
which must be placed behind the 
globe via a deep sub-Tenon 
approach.  In addition, all subjects 
• To improve 
safety and to 
prevent potential 
inflammatory 
response to 
therapy, the 
steroid regimen 
has been 
modified.  A 
standardized 
adult starting 
dose of 60 mg 
has been selected 
(rather than the 
previous 1mg/kg 
starting dose) 
and the taper has 
been lengthened 
to include 
coverage out to 
approximately 2 
months. A 2-
month visit has 
been added to 
assess the 
subjects at the 
end of the steroid 
therapy. 

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will be prescribed a course of oral 
corticosteroids. 
For adults, 60 mg of oral prednisone 
/ prednisolone will be prescribed for 
the initial 21 days (starting 3 days 
prior to surgery), followed by a 
weekly taper as follows for a total of 
9 weeks of treatment: 
Day -3 through day 17 (21 days): 
60 mg by mouth once daily 
Day 18 through day 24 (7 days): 
50 mg by mouth once daily 
Day 25 through day 31 (7 days): 
40 mg by mouth once daily 
Day 32 through day 38 (7 days): 
40 mg by mouth once daily 
Day 39 through day 45 (7 days): 
20 mg by mouth once daily 
Day 46 through day 52 (7 days): 
10 mg by mouth once daily 
Day 53 through day 59 (7 days): 5 
mg by mouth once daily.  
 
If at the Month-2 visit (Visit 5.9), 
inflammation is observed, 
corticosteroid therapy should be re-
initiated, via oral and/or intraocular 
route, based on the clinical condition 
of the subject, and the judgement of 
the investigator. 
For pediatric subjects, oral 
prednisolone/prednisone will also be 
started 3 days prior to surgery. The 
starting dose will be based on 
kilogram weight of the subject, up to 
a maximum of 60 mg starting dose 
(rounded to the nearest 1 mg). 
Subsequent doses will have 
multipliers to provide the 
appropriate taper over an additional 
6 weeks, for a total of 9 weeks of 
treatment.  See tapering regimen for 
pediatric subjects below: 
Day -3 through day 17 (21 days): 
Starting Dose (SD) 1 mg/kg by 
mouth once daily (maximum dose 
of 60 mg/once daily) 
Day 18 through day 24 (7 days): 
SD X 0.83 mg by mouth once 
daily 
Day 25 through day 31 (7 days): 
SD X 0.67 mg by mouth once 
daily 
Day 32 through day 38 (7 days): 
SD X 0.5 mg by mouth once daily 
• A pediatric 
regimen has also 
been added 
• General safety 
information 
regarding the use 
of steroids has 
been added 

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Day 39 through day 45 (7 days): 
SD X 0.33 mg by mouth once 
daily 
Day 46 through day 52 (7 days): 
SD X 0.17 mg by mouth once 
daily 
Day 53 through day 59 (7 days): 
SD X 0.08 mg by mouth once 
daily 
If at the Month-2 visit (Visit 5.9), 
inflammation is observed, 
corticosteroid therapy should be 
reinitiated, via oral and/or 
intraocular route, based on the 
clinical condition of the subject, and 
the judgement of the investigator.  
The local pediatric team should be 
involved with all children 
undergoing gene therapy surgery 
and should be available to give 
advice on the steroid doses used in 
each patient.  Modification of the 
protocol-defined steroid treatment 
are allowed based on 
recommendations of the pediatric 
team with approval from the 
Sponsor.  
For all subjects, while taking oral 
steroids, special note should be 
made to follow for potential side 
effects (e.g., increased IOP, 
cataracts, hypertension, elevated 
blood sugar, infections, 
gastritis/peptic ulcer disease, edema, 
electrolyte imbalance, mood 
changes, insomnia), and appropriate 
prophylaxis and/or therapy should 
be instituted as needed (e.g., 
treatment with proton pump 
inhibitors and/or valcyclovir; 
restriction of nonsteroidal anti-
inflammatory agents) 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Pages 38-39 
 
The subject or parent will sign and 
date one copy of the consent form in 
the presence of the investigator or 
his/her designee; where applicable, 
an assent form will be completed by 
the subject. 
• Moved for 
clarity 

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Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Pages 40-41 
• RPGR mutation screen 
(only if not conducted 
previously) 
• Colour vision test  
• Speed reading test 
• FST  
Footnote: 
It is recommended to 
measure BCVA and 
LLVA twice on the first 
day and once on the 
second day (prior to pupil 
dilation).  All 3 BCVA 
and all 3 LLVA values 
must be recorded in the 
eCRF.  The highest BCVA 
score will be used to 
define subject eligibility.  
LLVA should be 
conducted immediately 
after each BCVA 
assessment.   
• For Part I, RPGR gene mutation 
screen (only if not conducted 
previously); for Part II, prior 
documentation of a non-
synonymous mutation in the 
RPGR gene  
• ETDRS BCVA1 
• 
 
• Fundus autofluorescence 
• MAIA Microperimetry4 
• Fundus photography 
• Octopus 900 visual fields4,5 
• Contrast sensitivity test 
• 
AE and SAE monitoring 
•  
• 
 
• 
 
• Randomisation3 
Footnotes: 
1. For Part I subjects, BCVA is 
performed in triplicate at baseline. 
For Part II subjects, if the BCVA 
value at Visit 1 
(Screening/Baseline) is ≥ ± 10 
letter gain or loss in the study eye 
compared to the previous 
XOLARIS study visit (if 
applicable), then BCVA must be 
repeated an additional 2 times, 
resulting in a total of 3 BCVA 
measures at Visit 1. To facilitate 
the additional BCVA measures 
this visit should be conducted over 
2 days, with BCVA measured 
twice on Day 1 and once on Day 2 
(prior to pupil dilation). All 3 
BCVA values must be recorded in 
the eCRF. The highest score will 
be used to define subject 
eligibility. 
If the BCVA value at Visit 1 
(Screening/Baseline) is < ± 10 
letter difference in the study eye 
compared to the previous 
XOLARIS study visit, then 
BCVA will be collected once and 
will not be repeated. 
• Includes 
specifics on 
genetic 
diagnosis 
criterion 
• Assessments at 
Visit 1 now 
include 
,
 
 
• Specifies 
Octopus 900 
visual field 
• AE and SAE 
monitoring will 
occur from 
screening 
through end of 
study instead of 
SAE monitoring 
only 
• Removed 
reading test, 
colour vision 
and FST 
• Removed 
footnote 
information 
regarding 
BCVA and 
LLVA; added 
information in 
footnote related 
to Octopus 900 
and new 
assessments 
• Added new 
information 
regarding 
baseline BCVA 
assessment 
requirements 
 
 
 
 

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If subject was not previously in 
XOLARIS study, BCVA 
assessments at baseline must be 
triplicate. 
2. Only at sites with available 
technology. To facilitate testing of 
 and 
, the visit 
can be conducted over 2 days. 
3. 
 
 
4. Assessments collected in 
triplicate.  To facilitate triplicate 
testing, the visit should be 
conducted over 2 days. Visual 
field and microperimetry outputs 
will be sent to a CRC for review.  
Data will be generated and 
collated within the CRC and 
exported to the Sponsor or 
designee for inclusion in the study 
database. 
5. Octopus 900 perimetry is 
specified for visual field assessments 
only in Part II.  
 
 
 
 
• Specified in 
footnote that 
Octopus 900 is 
only specified in 
Part II 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Page 41 
In Part II, subjects will be 
then randomised to one of 
the AAV8-RPGR 
treatment groups (MTD 
cohort or active-control 
cohort) and subjects 
receiving treatment will 
remain masked to the 
treatment dose.   
In Part II, subjects will be informed 
of the randomisation outcome (i.e., 
AAV8-RPGR treatment or the 
Control group) and instructed to not 
reveal their treatment group 
assignment to the masked assessors 
during the study. Subjects 
randomised to the AAV8-RPGR 
treatment groups (along with the 
Investigators and sponsor) will 
remain masked to the assigned dose. 
New randomization 
and treatments 
specified 
Section 10.1  
Visit 1 
(Screening/Baseline 
Visit) 
Page 41 
Subjects will be given a 
21-day course of oral 
prednisone/prednisolone 
Subjects will be given a 21-day 
course of oral 
prednisone/prednisolone and 
instructed to start taking the drug 2 
(Part I) or 3 (Part II) days before 
their next study visit (Visit 2). 
Steroid course is no 
longer 21 days for 
all subjects 
Section 10.2  
 
At Visit 2, all subjects in the AAV8-
RPGR groups will visit the surgical 
• Ophthalmic exam 
has been added 

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(Day 0, 
Surgery/Injection 
Day Visit) 
Pages 41-42 
site, and the following assessments 
will be performed prior to surgery: 
• Full ophthalmic examination, 
including indirect ophthalmoscopy, 
slit lamp examination with IOP 
assessment, anterior chamber and 
vitreous inflammation grading, and 
LOCS III cataract grading 
 
It may be necessary for subjects to 
undergo a pre-surgical workup 
according to local hospital 
procedures (e.g., blood draw for 
anesthetist) which are outside of the 
protocol-defined assessments. Any 
assessments performed outside of 
the protocol will not be collected as 
part of the study analyses. 
All subjects will be treated at the 
time of surgery with up to 1 mL of 
triamcinolone (40 mg/mL), placed 
behind the globe via a deep sub-
Tenon approach. 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time. 
Sites will conduct the following 
assessments during the telephone 
call: 
• 
AE/SAE monitoring 
• 
Concomitant medication 
review. 
• Language added 
because one arm 
is untreated in 
Part II 
• Added language 
specifying that 
other non-study 
procedures may 
be necessary but 
will not be 
collected 
• Added new local 
steroid therapy 
added at time of 
surgery 
• Added how the 
untreated arm 
will be assessed 
through a 
telephone call at 
that visit. 
Section 10.3  
Visit 3  
(Day 1 Post-
Operative Visit) 
Page 42-43 
 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time.  
Sites will conduct the following 
assessments during the telephone 
call: 
• 
AE/SAE monitoring 
• 
Concomitant medication 
review. 
Added how the 
untreated arm 
will be assessed 
through a 
telephone call at 
that visit. 
Section 10.4 Visit 4 
(Day 7 Post-
Operative Visit) 
Page 43 
 
Subjects in the Control group will 
receive a study visit Telephone Call 
at the agreed upon date and time.  
Sites will conduct the following 
assessments during the telephone 
call: 
• 
AE/SAE monitoring 
Added how the 
untreated arm 
will be assessed 
through a 
telephone call at 
that visit. 

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• 
Concomitant medication 
review. 
Section 10.5   
Visit 5 (Month 1) 
Page 43 
 
• MAIA Microperimetry 
• Specified MAIA 
microperimetry  
Section 10.6   
Visit 5.9 (Month 2) 
Page 42 
 
At Visit 5.9, the following 
assessments will be performed: 
• Collection of safety blood samples 
(haematology and clinical 
chemistry) 
• Full ophthalmic examination, 
including indirect 
ophthalmoscopy, a slit-lamp 
examination, IOP, anterior 
chamber and vitreous 
inflammation grading and LOCS 
III cataract grading 
• ETDRS BCVA 
• SD-OCT 
• Fundus autofluorescence 
• MAIA Microperimetry 
• Viral shedding 
• Immunogenicity sampling 
• AE/SAE monitoring 
• Concomitant medication review 
• Corticosteroid compliance review 
New visit added to 
better monitor 
safety of subjects 
This visit is 
denoted as Visit 5.9 
in order to maintain 
the visit numbering 
in the EDC 
Section 10.7   
Visit 6 (Month 3) 
Page 42-43 
• 
Colour vision test 
Footnote: 
It is recommended to 
measure BCVA and 
LLVA twice on the first 
day and once on the 
second day (prior to pupil 
dilation).  All 3  BCVA 
and all 3 LLVA values 
must be recorded in the 
eCRF.  LLVA should be 
conducted immediately 
after each BCVA 
assessment.    
• MAIA Microperimetry 
• Octopus 900 visual fields1 
 
 
Footnotes: 
 
1. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
 
 
• Month 3 added 
new 
assessments;  
• removed color 
vision test 
• specified MAIA 
microperimetry 
• 
 
 
 
 
 
• Specified in 
footnote that 
Octopus 900 is 
only specified in 
Part II 
•  Removed 
footnote 

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information in 
BCVA and 
LLVA 
Section 10.8. 
Visit 7 (Month 6) 
Pages 45-46 
• 
Colour vision test 
• 
Speed reading 
test 
• 
FST 
• 
 
• 
MAIA Microperimetry 
• 
Octopus 900 visual fields2 
• 
 
Footnotes: 
 
 
 
2. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
• Removed color 
vision, speed 
reading, and 
FST; 
• 
 
 
•  specifies MAIA 
microperimetry 
and Octopus 900 
visual field 
Section 10.9. 
Visit 8 (Month 9) 
Page 46 
• 
Fundus 
autofluorescence 
 
• MAIA Microperimetry 
 
• Removed 
autofluorescence; 
• MAIA 
microperimetry 
specified 
Section 10.10. 
Visit 9 (Year 1) 
Pages 46-47 
• 
Colour vision test  
• 
Speed reading 
test 
• 
FST 
• 
 
• 
MAIA Microperimetry 
• 
Octopus 900 visual fields2,3 
• 
1 
• 
 
Footnote: 
 
 
 
 
2. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
 
 
Subjects who develop cataracts may 
undergo cataract surgery if deemed 
clinically necessary; if surgery is 
performed, it should be carried out at 
least 4 weeks before Visit 9 (Year 1) 
or Visit 11 (Year 2) for Part II and 
Part I subjects, respectively.   
• Removed color 
vision, reading 
and FST 
• 
, 
,  
• Specified MAIA 
microperimetry 
and Octopus 900 
visual field with 
associated 
footnotes 
• Differing times 
for Part I and 
Part II for 
window between 
potential cataract 
surgery and end 
of study visits 
• 
 
 
 
 
 
• Specified in 
footnote that 

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Octopus 900 is 
only specified in 
Part II 
Section 10.11. 
Visit 10 (Month 18) 
Page 47 
 
(Part I Subjects Only) 
Specified that Visit 
11, Month 18 is 
only for subjects of 
Part I 
Section 10.12. 
Visit 11 (Year 2) 
Page 47-48 
• 
Colour vision test  
• 
Speed reading test 
• 
FST  
(Part I Subjects Only) 
• Specified that 
Visit 12, Month 
24 is only for 
subjects of Part I 
• Removed 
assessments 
Section 10.13 
Early Termination 
(ET) Visit 
Page 48 
• Colour vision test  
• Speed reading test 
• FST 
 
 
• MAIA Microperimetry 
• Octopus 900 visual fields2,3 
•
 
Footnotes: 
 
 
2. Octopus 900 perimetry is 
specified for visual field 
assessments only in Part II.  
3. Part II only. 
• Added to ET 
visit, if possible, 
 MAIA 
Microperimetry, 
, and 
associated 
footnotes 
• Removed colour 
vision test, 
reading test, FST 
Section 10.14 
Unscheduled Visits 
Page 49 
 
• Microperimetry, if clinically 
feasible 
• Added 
microperimetry 
to unscheduled 
visit, if clinically 
feasible 
Section 11.1  
Best Corrected 
Visual Acuity 
Page 50 
BCVA will be performed 
in triplicate over a 2-day 
period at Visits 1,9 and 11  
(or ET Visit) for all 
subjects.  It is 
recommended that BCVA 
will be conducted twice on 
the first day and once on 
the second day. All values 
will be entered in the 
eCRF. 
For Part I subjects, BCVA will be 
performed in triplicate over a 2-day 
period at Visits 1, 9 and 11 (or ET 
Visit) for all subjects.  It is 
recommended that BCVA will be 
conducted twice on the first day and 
once on the second day. All values 
will be entered in the eCRF. 
 
For Part II subjects, if the BCVA 
value at Visit 1 
(Screening/Baseline) is ≥ ± 10 letter 
gain or loss in the study eye 
compared to the previous 
XOLARIS study visit (if 
applicable), then BCVA must be 
repeated an additional 2 times, 
resulting in a total of 3 BCVA 
measures at Visit 1. To facilitate the 
New instructions 
on BCVA 
triplicate 
requirement 

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additional BCVA measures this 
visit should be conducted over 2 
days, with BCVA measured twice 
on Day 1 and once on Day 2 (prior 
to pupil dilation). All 3 BCVA 
values must be recorded in the 
eCRF. The highest score will be 
used to determine subject eligibility. 
If the BCVA value at Visit 1 
(Screening/Baseline) is < ± 10 letter 
difference in the study eye 
compared to the previous 
XOLARIS study visit, then BCVA 
will be collected once and will not 
be repeated. 
If subject was not previously in 
XOLARIS study, BCVA 
assessments at baseline must be 
performed in triplicate. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Section 11.5  
MAIA 
Microperimetry 
Page 51 
 
MAIA Microperimetry will be 
conducted for both eyes at the times 
indicated in Table 3, Section 17.1.  
Microperimetry will be performed 
on both eyes in triplicate over a 2-
day period at Visit 1 for all subjects. 
The final assessment should be used 
to determine subject eligibility.  
If at subsequent visits there are 
obvious technical challenges or the 
subject is not performing the 
assessment as expected from 
previous visits (e.g. distracted, large 
number of false positive responses, 
not maintaining fixation, etc), then 
the assessment may be repeated and 
Specifies that 
MAIA 
microperimetry 
will be performed 
in triplicate at Visit 
1 only or if there is 
an inconsistent 
reading at other 
visits  

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the second assessment should be 
used for that study visit.  
Section 11.6  
Visual Fields 
Page 51 
 
In Part II, visual fields should be 
assessed using the Octopus 900 
perimeter. 
Specifies that 
Octopus 900 visual 
field will be 
conducted during 
Part II. 
Section 11.7. 
Contrast Sensitivity 
Page 52 
Contrast sensitivity will be 
measured prior to pupil 
dilation using a Pelli 
Robson chart. 
 
No longer specifies 
using the Peli-
Robson chart. 
Section 11.8 
Low Luminance 
Visual Acuity 
Page 52 
The test should be 
performed after before 
BCVA testing and prior to 
pupil dilation. 
 
 
 
 
LLVA should be 
performed in triplicate 
over a 2-day period at 
Visit 1 and , Visit 9 8 
(Month 3) and Visit 11 (1 
Year) (or the ET Visit) for 
all subjects, if applicable.  
It is recommended that 
LLVA will be conducted 
twice on the first day and 
once on the second day. 
All values will be entered 
into the eCRF. 
The test should be performed before 
BCVA testing and pupil dilation. 
LLVA is no longer 
conducted in 
triplicate; it is now 
conducted prior to 
BCVA testing 
instead of after 
Full Field Stimulus 
Threshold Test 
Page 52 
FST will be measured for 
both eyes after a period of 
dark adaptation and at the 
times indicated in Table 3, 
Section 17.1 (Visit 1, 7, 9, 
11, ET) only at sites where 
the required FST 
equipment is available, as 
specified in the Study 
Operations Manual.  FST 
measurements will be 
taken by appropriately 
qualified technicians.  For 
complete technical 
specifications, refer to the 
Study Operations Manual. 
 
Removed 
assessment 

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Colour Vision 
Page 52 
Colour vision will be 
tested for both eyes prior 
to pupil dilation, at the 
times indicated in Table 3, 
Section 17.1.  Eyes will be 
tested separately and in the 
same order at each 
assessment.  
For colour vision testing, 
assessors will be 
appropriately qualified for 
conducting the 
assessment.   
 
Removed 
assessment 
Reading Test 
Page 52 
Reading performance will 
be evaluated prior to pupil 
dilation for both eyes at 
the times indicated in 
Table 3, Section 17.1.  The 
reading test will be 
provided to each site by 
the Sponsor; for complete 
user instructions, refer to 
the Study Operations 
Manual.  
For the reading test, 
assessors will be 
appropriately qualified for 
conducting the 
assessment.   
 
Removed 
assessment 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 

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Section 12.2.2 
Recording of 
Adverse Events 
Page 57 
 
AEs/SAEs… 
 
AEs/SAEs that the investigator 
becomes aware of, and which are 
deemed to have a relationship to the 
study drug should continue to be 
reported to NightstaRx following the 
completion of the study for a period 
of up to 5 years following surgery, 
until/unless the subject is enrolled in 
another NightstaRx study. 
AEs and SAEs will 
be collected from 
the time of 
informed consent 
to the end of study. 
 
New sentence 
added to mandate 
collection of AE 
information from 
subjects for up to 5 
years from the end 
of study 
Section 12.2.4 
Reporting of 
Serious Adverse 
Events and DLTs 
Page 57 
 
 
 
 
 
 
All cases that are fatal or 
life-threatening will be 
reported no later than 7 
days after the sponsor 
received the initial report 
from the Investigator. 
The sponsor may unmask any SAE 
reports that are serious, unexpected, 
and related to the study drug, as 
required, in accordance with safety 
reporting guidance and regulations. 
 
All cases that are fatal or life-
threatening will be reported 
immediately after the sponsor 
receives the initial report from the 
Investigator.   
Added language 
regarding 
unmasking per 
GCPs 
 
 
Shortened window 
for reporting SAEs 
per regional 
regulators 
Section 12.2.5  
Procedures for 
Unmasking 
Page 57 
 
Procedures for Unmasking 
The Investigator has the ability to 
unmask an individual subject’s 
treatment assignment, but this 
capability is restricted to medical 
emergencies in which knowledge of 
the subject’s treatment is critical to 
the Investigator’s ability to treat the 
subject. 
In such a case, the Investigator must 
first attempt to contact the Medical 
Monitor or backup to discuss the 
rationale for unmasking. 
If the Investigator determines that 
the conditions above are met, then 
s/he unmasks the subject through the 
New section added 
per GCPs regarding 
unmasking 
procedures 

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Electronic Data Capture (EDC) 
system, files the resulting 
confirmation in a restricted file until 
the end of the study, and notifies the 
Medical Monitor within 24 hours 
that the subject’s treatment 
assignment has been unmasked.  The 
Investigator will not communicate 
the treatment assignment to the 
Medical Monitor or to any sponsor 
or study team staff; nor should the 
treatment assignment be 
communicated to site staff other than 
those personnel who require that 
knowledge in order to treat the 
subject. 
The Investigator will ensure that the 
rationale, date, and time of 
unmasking is noted in the subject’s 
source documentation, but not the 
treatment assignment.  The medical 
emergency that necessitated 
unmasking must also be recorded in 
the source documentation and the 
case report form per standard study 
procedures. 
Section 13.1  
Sample Size 
Page 60 
A sample size of 30 
subjects at the MTD dose 
ensures that events with an 
incidence ≥10% will be 
identified with a 95% 
probability.   
Due to the nature of the study design 
of Part I, no formal sample size 
computation was performed. 
In Part II, A a sample size of 45 
subjects, 15 in each of 3 groups 
(high-dose, low-dose and untreated), 
ensures 80% power at 0.05 
significance level assuming that the 
treated arm has 50% probability of 
achieving ≥7 dB improvement at ≥5 
loci at Month 3 vs. 5% in the 
untreated control arm. 
Specified Part I and 
Part II sample size 
rationale 
 
 
Section 13.3.1 
Safety Analysis Set 
Page 60 
 
The Safety Analysis Set will consist 
of all subjects who receive study 
treatment (vitrectomy/AAV8-
RPGR) in Part I, and all subjects that 
are randomized in Part II. 
 
Section 13.3.2 Full 
Analysis Set 
Page 60 
The Full Analysis Set will 
include all subjects for 
whom data of at least 1 
post baseline efficacy 
assessment is available in 
at least one eye. 
The Full Analysis Set will include 
all subjects for whom data of at least 
1 post baseline efficacy assessment 
is available in the study eye. 
 

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Section 13.4 
Descriptive 
Statistics 
Page 60 
 
No formal statistical comparison 
will be performed in Part I, and 
statistical tests will be conducted for 
the efficacy endpoints in Part II. 
 
Summaries will be 
generated by dose and 
overall, in Part I and, by 
group (MTD dose, and 
low-dose) in Part II. 
Summaries will be generated by 
dose and overall, in Part I and, by 
group (high-dose, low-dose, 
untreated) in Part II. 
Included untreated 
arm 
Section 13.5 
Demographics and 
Baseline 
Characteristics 
Page 61 
 
Demographics and baseline ocular 
characteristics will be summarised 
for the safety analysis set and the 
full analysis set for Part I and Part II 
separately. 
 
Section 13.6 
Efficacy Analyses 
Page 61 
Efficacy assessments are 
ocular in nature and 
therefore will be tabulated 
by eye (Study Eye and 
Fellow Eye).  Efficacy 
data will be summarised 
using descriptive statistics 
(described in Section 
13.4).  
Change from baseline in 
BCVA will be tabulated 
by visit and by eye. 
Efficacy assessments are ocular in 
nature and therefore will be 
tabulated by eye (Study Eye and 
Fellow Eye).  Efficacy data will be 
summarised using descriptive 
statistics (described in Section 13.4). 
This will be done for each cohort in 
Part I, and each arm in Part II. 
Improvement in retinal sensitivity 
and change from baseline in retinal 
sensitivity will be tabulated by visit 
and by eye in each Part, and be 
compared between the randomized 
groups in Part II by visit for the 
study eye. 
 
Section 13.6.1 
Multiplicity 
Adjustment 
Page 61 
Alpha adjustment is not 
applicable in this 
exploratory Phase 1/2 
study study. 
No multiplicity adjustment is 
planned in the study. Part I is the 
dose-escalation to identify the MTD 
based on the evaluation of benefit 
and risk without any formal 
statistical comparisons, and 
therefore no multiplicity adjustment 
is needed. In Part II, the analysis at 3 
months for the primary efficacy 
endpoint will determine whether the 
study is positive or not. Each dose 
will be compared with the untreated 
control separately by Fisher’s Exact 
Test at 0.05 level (two-sided).  
Specifies Part I and 
Part II multiplicity 
adjustment 
requirements 
Section 13.8 
Interim Analyses 
Page 62 
In Part II, secondary 
endpoints will be analysed 
at 3, 6, 12, 18 and 24 
months with masking to 
treatment dose maintained. 
In Part II, the analysis after all 
subjects complete 3-month visit will 
evaluate the primary efficacy 
endpoint, and hence is not an interim 
analysis. The personnel who are 
involved in daily operation will 
 

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continued to be masked of the 
treatment information until study 
completion to minimize any 
operational bias.  Additional analysis 
and a final analysis will be 
conducted for regulatory 
interactions. 
Section 14.1 
Informed Consent 
Page 63 
 
This is an assessor-masked study. 
All subjects will be informed at the 
time of randomisation whether they 
have been randomised to the AAV8-
RPGR or Control group. However, 
subjects in the AAV8-RPGR 
treatment groups will be masked to 
the assigned dose. 
Masking and 
randomization 
information have 
been added 
Section 15.2  
Data Handling and 
Records 
Management 
Page 65 
(by KCT Data). 
(by KCT Data). 
 
Removes 
specification for 
KCT Data 
Section 15.4  
Time and Schedule 
of the Study 
Page 66 
The expected overall study 
duration is 36 months. 
Part I includes 24 months of follow-
up for each subject enrolled and 
treated.  Part II includes 12 months 
of follow-up for each subject 
enrolled and treated. 
Duration changed 
to 24 months for 
overall study 
duration of Part 1. 
This has been 
corrected to define 
the actual duration 
per subject and not 
the estimated 
duration to last 
patient last visit. 
Part II is defined 
similarly, i.e., with 
12 months of 
follow-up for each 
subject.  
Section 17.1 
Schedule of Study 
Procedures  
Page 69-71 
 
 
• Changes reflect 
changes in 
assessments 
detailed above 
under individual 
visits  
• Abbreviations 
updated 
• Footnotes 
updated 

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Section 17.1 
Schedule of Study 
Procedures 
Page 72-75 
a. 
 Subjects will 
take 1 mg/kg/day 
prednisone/prednisolone 
for a total of 10 days 
(beginning 2 days before 
the vector injection, on the 
day of injection, and then 
for 7 days); followed by 
0.5 mg/kg/day for 7 days; 
0.25 mg/kg/day for 2 days; 
and 0.125 mg/kg/day for 2 
days (21 days in total). 
Footnotes 
Removed details on 
steroid regimen. 
This information 
can be found in 
body of protocol. 
 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
Page 1 of 20 
 
SUMMARY OF CHANGES FOR CLINICAL STUDY PROTOCOL  
NSR-RPGR-01  
 
AAV8-RPGR 
 
A Dose Escalation, Phase 1/2 Clinical Trial of Retinal Gene Therapy for X-linked Retinitis 
Pigmentosa Using an Adeno-Associated Viral Vector (AAV8) Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
Indication: 
X-Linked Retinitis Pigmentosa 
Study Phase: 
1/2 
Sponsor: 
NightstaRx Ltd 
Wellcome Gibbs Building, 215 Euston Road 
London NW1 2BE, UK 
Telephone:  +44 (0) 207 611 2077 
Summary of Changes: 
Protocol Version 6.0 
18 MAY 2018 
CONFIDENTIALITY STATEMENT 
This protocol is the property of NightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. 
Persons to whom the information is disclosed must be informed that the information is 
CONFIDENTIAL and may not be further disclosed by them. 
 
 

AAV8-RPGR 
 
Version 6 
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18 MAY 2018 
 
Page 3 of 20 
 
Overview / Rationale 
This protocol amendment allowed for an expansion of an active-control cohort of subjects to 
occur concurrently with the expansion of the MTD cohort in a randomized, double-masked 
fashion. This change provides greater efficacy information through a comparison of low- and 
high-dose outcomes. The amendment also clarifies the consent procedures for subjects less under 
10 years of age, and removes assessments of low luminance best-corrected visual acuity, blood 
pressure, pulse, and safety blood sampling at various visits. The primary endpoint has been 
clarified regarding the incidence of dose-limiting toxicities (DLTs) and adverse events, and the 
secondary endpoints have been specified temporally.  Lastly, cohorts 5 and 6, which originally 
were optional, are now protocol-defined due to a lack of DLTs observed in the ongoing study in 
cohorts 1-4. Per the protocol, if DLTs are observed at cohort 5, no escalation to cohort 6 will 
occur. 
 
SUMMARY OF CHANGES  
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Sponsor Approval 
Page 2 
 MD 
 
, MD 
 
Designated Sponsor 
approval has changed 
Contact 
Information 
Page 4 
  
 
Personnel change 
---- 
 
PhD 
New personnel added 
Synopsis  
Primary Endpoint 
Page 5 
The primary endpoint is the 
assessment of safety and 
tolerability of a single sub-
retinal injection of AAV8 
RPGR in subjects with a 
genetically confirmed XLRP, 
due to retinitis pigmentosa 
GTPase regulator (RPGR) 
mutation, over a 24-month 
period. 
The primary safety endpoint 
is incidence of dose-limiting 
toxicities (DLTs) and 
treatment-emergent adverse 
events (TEAEs) over a 24-
month period.  
Clarified endpoint of 
analysis 
Synopsis 
Secondary 
Endpoints Page 5 
• Changes from baseline in 
spectral domain optical 
coherence tomography (SD-
OCT) 
• Changes from baseline in 
best corrected visual acuity 
(BCVA)  
• Changes from baseline in 
autofluorescence 
• Changes from baseline in 
microperimetry 
• Changes from baseline in 
microperimetry at 3, 6, 12, 
18 and 24 months 
• Changes from baseline in 
best-corrected visual acuity 
(BCVA) at 3, 6, 12, 18, and 
24 months 
• Changes from baseline in 
spectral domain optical 
coherence tomography (SD-
OCT) at 3, 6, 12, 18 and 24 
months 
Added time points for 
precision of analyses; 
changed order 

AAV8-RPGR 
 
Version 6 
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Page 4 of 20 
 
SUMMARY OF CHANGES  
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Version 6.0, 18 MAY 2018 
Section, Page 
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• Changes from baseline in 
autofluorescence at 3, 6, 12, 
18 and 24 months 
Synopsis 
Exploratory 
Endpoint Page 5 
 
 
 
 
 
Synopsis Study 
Design Page 5-6 
This is a multi-centre, open-
label, single ascending dose 
interventional study of 
AAV8-RPGR in adult male 
subjects with genetically 
confirmed XLRP. 
This is a Phase 1/2, first-in-
human, multi-centre, dose-
escalation interventional study 
of AAV8-RPGR in male 
subjects with genetically 
confirmed XLRP. The study 
will be conducted in two 
parts: Part I is a dose 
escalation study, Part II is a 
Maximum Tolerated Dose 
(MTD) expansion study (as 
determined in Part I). 
The study design 
description now 
includes Part I and 
Part II 
Only 1 eye will receive 
treatment (the “study eye”), 
with the contra-lateral eye 
serving as the control (the 
“control eye”) 
Only 1 eye will receive 
treatment (the “study eye”), 
and the untreated eye will be 
designated as the “fellow 
eye”. 
More clarity around 
the definition of the 
fellow eye 
The study will use a 3+3 
escalation scheme (Storer, 
1989) for administration of 
AAV8-RPGR. Initially, the 
study will involve up to 4 
dose cohorts, with AAV8-
RPGR doses of 5 × 109 
genome particles (gp) 
(Cohort 1), 1 × 1010 gp 
(Cohort 2), 5 × 1010 gp 
(Cohort 3) and 1 x 1011 gp 
(Cohort 4). 
Part I: Dose-Escalation Study 
Dose escalation part of the 
study will use a 3+3 
escalation scheme (Storer, 
1989) and will involve up to 6 
AAV8-RPGR dose cohorts: 5 
× 109 genome particles (gp) 
(Cohort 1), 1 × 1010 gp 
(Cohort 2), 5 × 1010 gp 
(Cohort 3), 1 x 1011 gp 
(Cohort 4), 2.5 x 1011 gp 
(Cohort 5), and 5 x 1011 gp 
(Cohort 6). 
Cohorts 5 and 6 have 
been added to the 
dose-escalation 
scheme; 
Dose limiting toxicities 
(DLTs) are defined as any of 
the following events 
considered to be related to 
AAV8-RPGR: 
• Sustained decrease in 
BCVA of ≥30 letters on the 
Early Treatment of 
Diabetic Retinopathy Study 
Same text moved to the sixth 
paragraph of Study Design. 
To clarify the two 
parts of the study, 
DMC and DLT 
definitions have been 
moved to the end of 
the Study Design 
description 

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(ETDRS) chart compared 
to baseline. Sustained is 
defined as lasting 48 hours 
or more until recovery, 
with recovery defined as 
visual acuity (VA) 
returning to within 10 
letters of baseline VA. An 
exception is made for 
surgery-related events 
occurring in close temporal 
association (within <24 
hours) of the surgery. 
• Vitreous inflammation, 
vitritis (>Grade 3 using 
standardised Nussenblatt 
vitreous inflammation scale 
grading) (Nussenblatt et al., 
1985).  
• Any clinically significant 
retinal damage observed 
(e.g., retinal atrophy) that is 
not directly attributed to 
complications of surgery.  
Any clinically relevant 
suspected unexpected serious 
adverse reaction (as defined 
in the Investigator’s 
Brochure), with the 
exception of vision loss or 
vision-threatening events (as 
defined in Section 12.2.1.2). 
Synopsis Study 
Design 
Page 6 
An independent Data 
Monitoring Committee 
(DMC) will review safety data 
before confirming whether 
escalation to a higher dose 
level can occur. There is a 
potential for surgical 
complications resulting in 
safety events that meet the 
criteria for a DLT. In such 
cases, the DMC will make the 
final adjudication as to 
whether the event is a DLT.  
The DMC will review safety 
data for each cohort when at 
Same text moved to the fifth 
paragraph of Study Design 
To clarify the two 
parts of the study, 
DMC and DLT 
definitions have been 
moved to the end of 
the Study Design 
description. 

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least 3 subjects have been 
dosed at a particular level. 
However, if 2 subjects within 
a cohort have a DLT(s), 
dosing will not proceed to 
subsequent subjects until 
safety data are reviewed by 
the DMC. For the purpose of 
making decisions regarding 
dose escalation, the DMC will 
review safety data collected 
for at least 4 weeks from each 
subject in the last dosed 
cohort. In addition, the DMC 
will review cumulative safety 
data collected from all 
previously-dosed cohorts and 
take these findings into 
consideration when making 
decisions on dose escalation.  
Synopsis Study 
Design Page 6 
If ≥2 subjects within a cohort 
(3 or 6 subjects) have a 
DLT(s), then the maximum 
tolerated dose (MTD) will be 
identified as the previous 
(lower) dose, and 15 to 30 
additional subjects will be 
treated at the MTD (MTD 
cohort) 
If ≥2 subjects within a cohort 
(3 or 6 subjects) have a 
DLT(s), then the maximum 
tolerated dose (MTD) will be 
identified as the previous 
(lower) dose. 
Addition of Part II 
description provides 
this information in 
more detail with 
active-control cohort. 
If subjects in Cohorts 1-4 
tolerate treatment, the sponsor 
and DMC will review all 
cumulative safety data and 
determine if further dose 
escalation (2.5 x 1011 gp 
[Cohort 5], and subsequently 5 
x 1011 gp [Cohort 6]) is 
acceptable. If dose escalation 
is considered to be feasible the 
same procedure described 
above for Cohorts 1-4 will be 
followed. If dose escalation is 
not deemed feasible, then  15 
to 30 additional subjects will 
be treated at the defined MTD. 
 
Text removed. 
Cohorts 5 and 6 are 
now protocol-
specified. Expansion 
is now described in 
Part II. 
 
Part II: MTD Expansion 
Study 
New text describes 
Part II. 

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Once the MTD has been 
identified, up to 45 additional 
subjects will be randomized, 
in a 2:1 allocation ratio.  
Subjects will receive AAV8-
RPGR either at the MTD 
(MTD cohort), or at a low 
dose (active-control cohort), 
three dose-levels below the 
MTD ( e.g., low dose = 5 x 
1010 gp if MTD = 5x1011 
gp).  Part II of the study will 
be randomized and double-
masked to the assigned dose, 
and open-label to the 
treatment administration. 
Synopsis,  
Number of 
Subjects Page 6 
In a 4-cohort trial, it is 
anticipated that up to 42 
subjects will be enrolled, 
dependent on toxicity 
observed. 
Overall, the study is expected 
to enroll approximately 63 
subjects: 18 in Part I and 45 in 
Part II. 
Numbers are 
increased for Cohorts 
5 and 6 in Part I and 
for expansion with 
active-control cohort 
in Part II. 
Synopsis,  
Diagnosis and 
Inclusion Criteria 
Page 7 
Are willing and able to give 
informed consent for 
participation in the study 
Subject / parent is Are 
willing and able to give 
informed consent for 
participation in the study 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects. 
Are male and able to comply 
and adequately perform all 
study assessments 
• Cohorts 1-4 (5 and 6, if 
applicable): ≥18 years of 
age 
• MTD cohort: ≥10 years of 
age 
Are male and able to comply 
and adequately perform all 
study assessments 
• 
Study Part I: ≥18 years 
of age 
• 
Study Part II: ≥10 years 
of age 
States more clearly 
the two parts of the 
study with age cut-
offs 
Have active disease clinically 
visible within the macular 
region.  
Have active disease clinically 
visible within the macular 
region in both eyes and 
defined as follows: 
 ellipsoid zone (EZ) on 
SD-OCT measured at 
screening, must be within 
the nasal and temporal 
border of any B-scan, and 
not be visible on the most 
inferior and superior B-
scan 
Allows for a more 
specific definition of 
the disease in at least 
one eye, with 
anatomical 
characteristics that 
might demonstrate 
improvement with 
interventions 

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BCVA in both eyes that 
meets the following criteria, 
based on the cohort level: 
o 
Cohort 4 (5 and 6, if 
applicable) and MTD 
cohort: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better than 
or equal to 6/60 or 
20/200 Snellen acuity) 
BCVA in both eyes that 
meets the following criteria, 
based on the cohort level: 
o 
Cohort 4-6 and study 
part II: better than or 
equal to BCVA of 34 
ETDRS letters 
(equivalent to better than 
or equal to 6/60 or 
20/200 Snellen acuity) 
 
Synopsis, Exclusion 
Criteria 
Page 8 
Are unwilling to use barrier 
contraception methods for a 
period of 3 months following 
treatment with AAV8-RPGR 
Are unwilling to use barrier 
contraception methods (if 
applicable), for a period of 3 
months following treatment 
with AAV8-RPGR 
Inclusion of pediatric 
subjects 
Synopsis, Test 
Product, Dosage, 
and Mode of 
Administration 
Page 8 
Subjects will be assigned to 1 
of the following potential 
cohorts: 
• Cohort 1: 5 × 109 gp/0.1 mL 
• Cohort 2: 1 × 1010 
gp/0.1 mL 
• Cohort 3: 5 × 1010 
gp/0.1 mL 
• Cohort 4: 1 x 1011 gp/0.1 
mL 
MTD: As identified from 
Cohorts 1-4. 
Subjects will be assigned to 1 
of the following AAV8-RPGR 
dose cohorts: 5 × 109 gp/mL, 
1 × 1010 gp/mL, 5 × 1010 
gp/mL, 1 x 1011 gp/ mL, 2.5 x 
1011 gp/mL, or 5 x 1011 
gp/mL.  
 
Addition of cohorts 5 
and 6; 
Addition of cohorts 5 
and 6 to protocol 
specified instead of 
optional if no DLTs 
are observed; error 
corrected in 
concentration / mL 
Synopsis, 
Reference Therapy 
The contralateral eye will 
serve as a comparator for 
efficacy in this study. The 
contralateral eye will not 
undergo surgery or receive 
any study treatment. 
In Part I, no Reference 
therapies will be administered. 
In Part II, a low dose of 
AAV8-RPGR (active-control 
cohort) will be the Reference 
therapy, the concentration of 
which will be three dose 
levels from MTD. 
Separation of Part I 
and II as there is an 
active-control cohort 
in Part II 
Synopsis, 
Statistical 
Methodology 
Summaries will be generated 
by dose and overall. 
AEs will be summarised by 
system organ class and 
preferred term. Both the 
number of eyes/subjects 
experiencing an AE and the 
number of events will be 
summarised. Similar 
The primary objective of the 
study is to evaluate the safety 
profile of AAV8-RPGR. The 
primary safety endpoint is 
incidence of DLTs and 
TEAEs over a 24-month 
period. The analysis 
population for the safety 
analysis will include all 
Statistical 
methodology is 
specified.  

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summaries will be produced 
for study drug/procedure-
related AEs, AEs leading to 
discontinuation, and serious 
AEs. AEs will also be 
summarised by maximum 
severity, relationship to study 
drug/procedure, and time to 
onset. Separate summaries 
will be generated for ocular 
and systemic AEs. 
Summary statistics will be 
presented for both eyes (Study 
Eyes versus Control Eyes).  
patients enrolled in the study 
who received AAV8-RPGR 
treatment.  
A sample size of 30 subjects 
at the MTD dose ensures that 
events with an incidence 
≥10% will be identified with a 
95% probability. 
 
 
 
 
 
Summary statistics will be 
presented for both eyes (Study 
Eye and Fellow Eye).  
(text continues unchanged) 
A by-subject listing of SAEs 
and DLTs will be provided. 
Section 6 
6.2.1 Primary 
Endpoint 
The primary endpoint is the 
assessment of safety and 
tolerability of a single sub-
retinal injection of AAV8-
RPGR in subjects with 
genetically confirmed XLRP, 
due to an RPGR mutation, 
over a 24-month period.  
The primary safety endpoint is 
incidence of dose-limiting 
toxicities (DLTs) and 
treatment-emergent adverse 
events (TEAEs) over a 24-
month period.  
Clarified the endpoint  
6.2.2 Secondary 
Endpoints 
• Changes from baseline in 
spectral domain optical 
coherence tomography 
(SD-OCT) 
• Changes from baseline in 
best-corrected visual acuity 
(BCVA) 
• Changes from baseline in 
autofluorescence   
• Changes from baseline in 
microperimetry. 
• Changes from baseline in 
other anatomic and 
functional outcomes. 
 
 
• Changes from baseline in 
microperimetry at 3, 6, 12, 
18, and 24 months 
• Changes from baseline in 
best-corrected visual 
acuity (BCVA) at 3, 6, 12, 
18, and 24 months 
• Changes from baseline in 
spectral domain optical 
coherence tomography 
(SD-OCT) at 3, 6, 12, 18, 
and 24 months 
• Changes from baseline in 
autofluorescence at 3, 6, 
12, 18, and 24 months 
• Changes from baseline in 
other anatomic and 
Added specific time 
points for analyses; 
changed order 

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functional outcomes at 3, 
6, 12, 18 and 24 months 
7.1 Overall Study 
Design 
This is a multi-centre, open-
label, single ascending dose 
interventional study of AAV8-
RPGR in adult male subjects 
with genetically confirmed 
XLRP.  
 
This is a Phase 1/2, first-in-
human, multi-centre, dose-
escalation interventional study 
of AAV8-RPGR in male 
subjects with genetically 
confirmed XLRP. The study 
will be conducted in two 
parts: Part I is a dose 
escalation study, Part II is a 
Maximum Tolerated Dose 
(MTD) expansion study (as 
determined in Part I). 
 
7.1 Overall Study 
Design 
Only 1 eye will receive 
treatment (the “study eye”), 
with the contra-lateral eye 
serving as the control (the 
“control eye”).   
Only one eye will receive 
treatment (the “study eye”), 
and the untreated eye will be 
designated as the “fellow 
eye.”   
Clearer definition of 
untreated eye 
7.2 Dose-Limiting 
Toxicities 
…. 
In the event that a DLT occurs 
at any time during the study, 
the site is to report the event to 
the sponsor within 24 hours of 
occurrence. 
When triplicate BCVA 
assessments are performed at 
screening, the median BCVA 
result will be used for change-
from-baseline BCVA 
computation. 
In the event that a DLT occurs 
at any time during the 
study,… 
Clarified change from 
baseline computation 
for DLTs when 
triplicate assessments 
are performed 
7.3 Dose Escalation 
7.3 Dose Escalation Scheme 
 
7.3 Part I: Dose-Escalation 
Study 
Changed Header to 
reflect Part I of study 
Initially, the study will involve 
up to 4 dose cohorts, with 
AAV8-RPGR doses of 5 × 109 
gp (Cohort 1), 1 × 1010 gp 
(Cohort 2), 5 × 1010 gp 
(Cohort 3), and 1 x 1011 gp 
(Cohort 4).   
The study will involve up to 6 
dose cohorts, with AAV8-
RPGR doses of 5 × 109 gp 
(Cohort 1), 1 × 1010 gp 
(Cohort 2), 5 × 1010 gp 
(Cohort 3), and 1 x 1011 gp 
(Cohort 4), 2.5 x 1011 gp 
(Cohort 5), and 5 x 1011 gp 
(Cohort 6). 
Addition of cohorts 5 
and 6 to protocol 
specified instead of 
optional if no DLTs 
are observed 
If ≥2 subjects within a cohort 
(3 or 6 subjects) have a 
DLT(s), then the maximum 
tolerated dose (MTD) will be 
identified as the previous 
(lower) dose, and an 
additional 15 to 30 subjects 
If ≥2 subjects within a cohort 
(3 or 6 subjects) have a 
DLT(s), then the maximum 
tolerated dose (MTD) will be 
identified as the previous 
(lower) dose. 
 

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will be treated at the MTD 
(MTD cohort). 
7.4 Part II: MTD 
Expansion Study 
 
PART II: MTD EXPANSION 
STUDY 
Once the MTD has been 
identified, up to 45 additional 
subjects will be randomized, 
in a 2:1 allocation ratio. 
Subjects will receive AAV8-
RPGR either at the MTD 
(MTD cohort), or at a low 
dose (active-control cohort), 
three dose-levels below the 
MTD (e.g., low dose = 5 x 
1010 gp if MTD = 5x1011 
gp).  Part II of the study will 
be randomized and double-
masked to the assigned dose, 
and open-label to the 
treatment administration. 
 
7.5 Number of 
Subjects 
In a 4-cohort trial, it is 
anticipated that up to 42 
subjects will be enrolled, 
dependent on toxicity 
observed. 
Overall, the study is expected 
to enroll approximately 63 
subjects: 18 in Part I and 45 in 
Part II. See Section 13.1 for 
rationale.  
 
7.6 Discussion of 
Study Design and 
Dose Selection  
Once the safety and 
tolerability of AAV8-RPGR is 
demonstrated in adults, 
subjects ≥10 years of age will 
be enrolled in the MTD 
cohort. 
Once the MTD has been 
identified and the safety and 
tolerability of AAV8-RPGR is 
demonstrated in adults, 
subjects ≥10 years of age will 
be enrolled in Part II of the 
study. 
 
7.6 Discussion of 
Study Design and 
Dose Selection  
 
In Part II, subjects will be 
randomized to the ‘MTD 
cohort’ or the ‘low-dose 
active-control cohort’.  This 
allows for a parallel, active-
control group and masking of 
the treatment dose, which will 
enhance the robustness of the 
efficacy and safety outcomes.  
The active-control cohort will 
be three dose-levels below the 
MTD. This assures a 1-1.5-log 
difference in dose between 
these two cohorts, and allows 
for identifying a dose 
 

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response while mitigating the 
possibility of a subtherapeutic 
low dose. 
8.1 Inclusion 
Criteria 
1. Are willing and able to 
provide informed consent for 
participation in the study 
 
1. Subject / parent is willing 
and able to provide informed 
consent for participation in the 
study 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
2.  
• 
Cohorts 1-4 (5 and 6, if 
applicable): ≥18 years of 
age 
• 
MTD cohort: ≥10 years 
of age 
2. 
• 
Part I: ≥18 years of age 
• 
Part II: ≥10 years of age 
 
5.  
Cohort 4 (5 and 6, if 
applicable) and MTD cohort: 
5.  
Cohort 4-6 and Part II: 
 
8.2 Exclusion 
Criteria  
2.  
Are unwilling to use barrier 
contraception methods, for a 
period of 3 months following 
treatment with AAV8-RPGR 
2. 
Are unwilling to use barrier 
contraception methods (if 
applicable), for a period of 3 
months following treatment 
with AAV8-RPGR 
 
8.3 Subject 
Withdrawal 
Criteria 
For subjects who withdraw 
consent, data will be collected 
through their last available 
study visit. 
For subjects who withdraw 
consent/assent, data will be 
collected through their last 
available study visit. 
Assent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
9.1 Treatments 
Administered 
Subjects will receive either a 
dose of 5 × 109 gp (Cohort 1), 
1 × 1010 gp (Cohort 2), 5 × 
1010 gp (Cohort 3) or 1 x 1011 
gp (Cohort 4) AAV8-RPGR.  
In applicable, additional 
cohorts 5 (2.5 × 1011 gp ) and 
6 (5 x10 11 gp) may be added 
depending on observed 
toxicity (see Section 7.3 for 
details). 
Subjects will receive an 
AAV8-RPGR dose of 5 × 109 
gp (Cohort 1), 1 × 1010 gp 
(Cohort 2), 5 × 1010 gp 
(Cohort 3), 1 x 1011 gp 
(Cohort 4), 2.5 × 1011 gp 
(Cohort 5), or 5 x 1011 gp 
(Cohort 6). (see Section 7.3 
for details). 
 
9.5 Randomisation 
Not applicable for this study. 
The dose-escalation portion of 
this study is not randomized.  
In Part II, after the study eye 
is assigned, subjects will be 
randomised in a 2:1 ratio to 
receive either AAV8-RPGR 
MTD or a lower dose of 
AAV8-RPGR, three dose-
 

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levels from MTD (e.g., low 
dose = 5 x 1010 gp if MTD = 5 
x 1011 gp) for the active-
control cohort.  
Randomisation will be 
generated using a validated 
system that automates the 
random assignment of 
treatment groups to 
randomisation numbers. Once 
a subject is deemed eligible, 
the investigative site (or 
authorised designee) will 
access the system, and the 
subject will be randomised 
using a standard blocked 
randomisation. The 
randomisation number will 
include the centre number and 
subject number. 
9.6 Study Masking 
Due to the invasiveness of the 
vitrectomy and sub-retinal 
injection, both the investigator 
and the subject will be 
unmasked to the study 
procedure. 
 
Part I of the study is open-
label. 
Part II is double masked 
(subject, surgeon, 
investigator/site team, sponsor 
will be masked to the assigned 
dose, and open-label with 
respect to the treatment 
administration). 
 
10.1 Visit 1 
(Screening 
/Baseline Visit) 
The subject will sign and date 
one copy of the consent form 
in the presence of the 
investigator or his/her 
designee. The original signed 
form will be retained at the 
study site and an additional 
copy will remain in the 
subject’s medical records; a 
copy will also be given to the 
subject. 
The subject or parent will sign 
and date one copy of the 
consent form in the presence 
of the investigator or his/her 
designee. The original signed 
form will be retained at the 
study site and an additional 
copy will remain in the 
subject’s medical records; a 
copy will also be given to the 
subject or parent. Where 
applicable, an assent form will 
be completed by the subject. 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
Screening procedures will 
consist of the following: 
 
Screening assessments will be 
considered baseline 
measurements and will consist 
of the following: 
 

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• 
Randomisation** 
**Randomisation for Part II 
only. 
 
Subjects who meet all of the 
inclusion criteria and none of 
the exclusion criteria will be 
enrolled into the study and 
assigned a subject number. 
Subjects who meet all of the 
inclusion criteria and none of 
the exclusion criteria will 
have a study eye assigned and 
be enrolled into the study.  In 
Part II, subjects will be then 
randomised to the AAV8-
RPGR treatment groups 
(MTD cohort or active-control 
cohort), and will remain 
masked to the treatment dose. 
See Section 9.5 for details on 
randomisation and assignment 
of subject numbers. 
 
LLVA 
 
Low luminance visual 
acuity testing 
removed; no rationale 
on first post-op day 
10.3 Visit 3 (Day 1 
Post-Operative 
Visit) 
Subjects will be reminded of 
the requirement to use barrier 
contraception for a period of 3 
months from the time of 
treatment. 
 
Where applicable, subjects 
will be reminded of the 
requirement to use barrier 
contraception for a period of 3 
months from the time of 
treatment. 
Inclusion of pediatric 
patients 
LLVA 
 
Low luminance visual 
acuity testing 
removed; no rationale 
on first post-op day 
Visit 4 (Day 7 Post-
Operative Visit) 
Blood pressure and pulse 
 
 
No rationale for vitals 
on month 1, increases 
study burden on site 
Visit 5 (Month 1) 
Blood pressure and pulse 
 
 
No rationale for vitals 
on month 1, increases 
study burden on site 
Visit 9 (Year 1) 
10.10 Visits 10 (Month 18  ± 
14 Days) and 11 (Year 2 ± 14 
Days, End of Study Visit) 
 
10.10 Visit 10 (Month 18 ± 14 
Days) 
The procedures are no 
longer identical on 
these two visits so 
they have been 
separated 

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10.10 Visits 10 
(Month 18  ± 14 
Days) and 11 (Year 
2 ± 14 Days, End of 
Study Visit) 
Visual fields 
Contrast sensitivity test 
 
 
These procedures 
have been removed 
from the visit to 
lessen the burden on 
the site. 
10.10 Visit 10 
(Month 18) 
• ETDRS BCVA* 
• LLVA* 
*Assessments collected in 
triplicate at Visit 11 (Year 2). 
To facilitate triplicate testing, 
the visit should be conducted 
over 2 days. It is 
recommended to measure 
BCVA and LLVA twice on 
the first day and once on the 
second day (prior to pupil 
dilation). All 3 BCVA and all 
3 LLVA values must be 
recorded in the eCRF. LLVA 
should be conducted 
immediately after each BCVA 
assessment.   
 
• 
ETDRS BCVA 
LLVA 
These assessments are 
no longer done in 
triplicate on this visit 
to lessen the burden 
on the site. 
 
10.11 Visit 11 (Year 2 ± 14 
Days, End of Study Visit) 
At Visits 11 the following 
ocular assessments will be 
performed: 
• Full ophthalmic 
examination, including 
indirect ophthalmoscopy, a 
slit-lamp examination, 
IOP, anterior chamber and 
vitreous inflammation 
grading and LOCS III 
cataract grading 
• ETDRS BCVA* 
• SD-OCT 
• LLVA* 
• Fundus autofluorescence 
• Microperimetry 
• Fundus photography 
• Visual Fields  
• Contrast sensitivity test 
 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
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Version 6.0, 18 MAY 2018 
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• Colour vision test  
• Speed reading test 
• FST  
• AE/SAE monitoring 
• Concomitant medication 
review 
• 
* Assessments 
collected in triplicate. 
To facilitate triplicate 
testing, the visit 
should be conducted 
over 2 days. It is 
recommended to 
measure BCVA and 
LLVA twice on the 
first day and once on 
the second day (prior 
to pupil dilation). All 
3 BCVA and all 3 
LLVA values must 
be recorded in the 
eCRF. LLVA should 
be conducted 
immediately after 
each BCVA 
assessment.   
10.11 Visit 11 
(Year 2) 
• 
Blood pressure and pulse 
Collection of safety blood 
samples (haematology and 
clinical chemistry) 
 
These have been 
removed as there was 
no rationale and 
lessened burden on 
the site. 
10.12 Early 
Termination Visit 
Details of the statistical 
analyses will be described 
separately in the Statistical 
Analysis Plan. 
• 
Summaries will be 
generated by dose and 
overall. 
For full details of the 
statistical analyses, please 
refer to the XIRIUS Statistical 
Analysis Plan (SAP). 
 
12.2.2 Recording of 
Adverse Events 
SAEs will be collected from 
the time the subject provides 
written informed consent 
through Visit 11 (or ET Visit 
or Unscheduled Visits, if 
applicable). 
SAEs will be collected from 
the time the subject or parent 
(where applicable) provides 
written informed consent 
through Visit 11 (or ET Visit 
or Unscheduled Visits, if 
applicable). 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
Page 17 of 20 
 
SUMMARY OF CHANGES  
PROTOCOL NSR-RPGR-01  
Version 6.0, 18 MAY 2018 
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12.2.3 Follow-up of 
Adverse Events 
Subjects who are withdrawn 
from the study as a result of a 
drug-related AE will be 
followed up until the event has 
resolved, subsided, stabilised 
or the subject withdraws 
consent or is lost to follow-up.   
All SAEs, regardless of 
attribution to study medication 
or the surgical procedure, 
should be followed-up until 
the event has resolved, 
subsided, stabilised or the 
subject withdraws consent or 
is lost to follow-up. 
Subjects who are withdrawn 
from the study as a result of a 
drug-related AE will be 
followed up until the event 
has resolved, subsided, 
stabilised or the subject or 
parent (where applicable) 
withdraws consent or is lost to 
follow-up.   
All SAEs, regardless of 
attribution to study medication 
or the surgical procedure, 
should be followed-up until 
the event has resolved, 
subsided, stabilised or the 
subject or parent (where 
applicable) withdraws consent 
or is lost to follow-up. 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
13.0 Statistical 
Considerations  
Due to the nature of the study 
design, no formal sample size 
computation was performed. 
 
Due to the nature of the study 
design, no formal sample size 
computation was performed. 
A sample size of 30 subjects 
at the MTD dose ensures that 
events with an incidence 
≥10% will be identified with a 
95% probability. 
Added sample size 
calculation 
13.1 Sample Size 
(Study Eyes versus Control 
Eyes) 
(Study Eyes versus Fellow 
Eyes). 
Clarified the 
definition of the 
untreated eye. 
13.4 Descriptive 
Statistics 
 
No formal statistical 
comparison will be 
performed (no p-value will 
be computed). 
 
Clarification 
Continuous data will be 
summarised over time using 
mean, standard deviation, 
median, minimum and 
maximum. 
 
Continuous data will be 
summarised over time using 
mean, and its 95% CI, 
standard deviation, median, 
minimum and maximum. 95% 
CIs will be 2-sided. 
Summaries will be generated 
by dose and overall, in Part I 
and, by group (MTD dose and 
low-dose) in Part II. 
Clarification 
Demographics will be 
summarised by subject and; 
Demographics and baseline 
ocular characteristics will be 
summarised for the safety 
Clarification 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
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Version 6.0, 18 MAY 2018 
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baseline ocular characteristics 
will be summarised by eye. 
 
analysis set and the full 
analysis set. 
13.5 Demographics 
and Baseline 
Characteristics 
(Study Eyes versus Control 
Eyes) 
(Study Eyes versus Fellow 
Eyes). 
Clarification 
13.6 Safety 
Analysis 
 
 
No formal statistical testing 
will be performed for safety 
analyses. Safety analyses will 
be performed on the Safety 
Analysis Set. 
Clarification 
13.7.1 Alpha 
Adjustment 
Alpha adjustment is not 
applicable in this study as no 
formal comparison will be 
performed. 
Alpha adjustment is not 
applicable in this exploratory 
Phase 1/2 study as no formal 
comparison will be 
performed. 
Clarification 
13.7 Interim 
Analysis 
 
 
 
 
 
 
 
Interim analysis 
added. 
13.8 Interim 
Analysis 
Subjects must personally sign 
and date the latest 
Independent Ethics 
Committee (IEC)/Institutional 
Review Board (IRB) approved 
version of the informed 
consent form before any 
study-specific procedures are 
performed. 
Subjects or parent (where 
applicable) must personally 
sign and date the latest IEC/ 
IRB approved version of the 
informed consent form before 
any study-specific procedures 
are performed. Where 
applicable a subject assent 
form will be obtained. 
Assent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
14.1 Informed 
Consent 
Written and verbal versions of 
the subject information and 
informed consent will be 
presented to the subjects 
detailing no less than 
Written and verbal versions of 
the subject information and 
informed consent will be 
presented to the subject or 
parents (where applicable) 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
The subject will be allowed as 
much time as needed to 
consider the information and 
the opportunity to question the 
investigator, 
The subject or parent (where 
applicable) will be allowed as 
much time as needed to 
consider the information and 
the opportunity to question the 
investigator, 
Parent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
Written informed consent will 
then be obtained by means of 
Written informed consent will 
then be obtained by means of 
Parent is included in 
all informed consent 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
Page 19 of 20 
 
SUMMARY OF CHANGES  
PROTOCOL NSR-RPGR-01  
Version 6.0, 18 MAY 2018 
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subject dated signature and 
dated signature of the person 
who presented and obtained 
the informed consent. The 
person who obtained the 
consent must be suitably 
qualified and experienced and 
have been authorised to do so 
by the investigator. A copy of 
the signed informed consent 
will be given to each subject. 
subject or parent (where 
applicable) dated signature 
and dated signature of the 
person who presented and 
obtained the informed 
consent. Where applicable, a 
subject assent form will be 
obtained. The person who 
obtained the consent/assent 
must be suitably qualified and 
experienced and have been 
authorised to do so by the 
investigator. A copy of the 
signed informed consent will 
be given to each subject or 
parent. 
language for inclusion 
of pediatric subjects 
The protocol, informed 
consent form, 
The protocol, informed 
consent/assent form, 
Assent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
14.2 
Ethical/Regulatory 
Review 
The study will be conducted in 
accordance with the relevant 
articles of the Declaration of 
Helsinki as adopted by the 
18th World Medical Assembly 
in 1964 and as revised in 
Tokyo (1975), Venice (1983), 
Hong Kong (1989), South 
Africa (1996), Scotland 
(2000), Washington (2002), 
Tokyo (2004), Seoul (2008), 
and Brazil (2013). 
The study will be conducted 
in accordance with the 
relevant articles of the 
Declaration of Helsinki. 
Unnecessary 
14.3 Regulatory 
Considerations 
Informed consent 
Informed consent/assent 
Assent is included in 
all informed consent 
language for inclusion 
of pediatric subjects 
Table 3 
Blood pressure and pulse 
 
Removed from Visit 
5, 9, ET; These have 
been removed as there 
was no rationale and 
lessened burden on 
the site. 
Collection of safety blood 
samples 
 
Removed from Visit 
ET; These have been 
removed as there was 
no rationale and 

AAV8-RPGR 
 
Version 6 
Summary of Changes: Protocol: NSR-RPGR-01 
 
18 MAY 2018 
 
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SUMMARY OF CHANGES  
PROTOCOL NSR-RPGR-01  
Version 6.0, 18 MAY 2018 
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lessened burden on 
the site. 
BCVA and LLVA 
 
Not in triplicate at 
Visit 10; there was no 
rationale and lessened 
burden on the site. 
 
Corticosteroid compliance 
review 
Added at Visits 2, 3, 
4, 5 
 
Randomisationn 
nPart II only 
Added at Visit 1 
LLVA 
 
Removed from Visits 
3, 4; there was no 
rationale and lessened 
burden on the site. 
 

AAV8-RPGR 
Protocol: NSR-RPGR-01
Protocol Version 4.0 
15 Dec 2017
 
CONFIDENTIAL
Page 1 of 5
 
 
1. 
TITLE PA 
SUMMARY OF CHANGES FOR  
CLINICAL STUDY PROTOCOL  
NSR-RPGR-01  
 
A Dose Escalation, Phase 1/2 Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
 
XIRIUS STUDY  
INDICATION: 
 
 
X-linked retinitis pigmentosa  
STUDY PHASE:  
 
1/2 
EUDRACT NUMBER:  
2016-003852-60 
SPONSOR: 
NightstaRx Ltd 
Wellcome Gibbs Building, 215 Euston Road 
London NW1 2BE, UK 
Telephone:  +44 (0) 207 611 2077 
 
SUMMARY OF CHANGES: Protocol Version 4.0  
 
 
 
 
 
15 Dec 2017 
 
CONFIDENTIALITY STATEMENT 
This protocol is the property of NightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. Persons 
to whom the information is disclosed must be informed that the information is CONFIDENTIAL 
and may not be further disclosed by them. 
 

AAV8-RPGR 
Protocol: NSR-RPGR-01
Protocol Version 4.0 
15 Dec 2017
 
CONFIDENTIAL
Page 2 of 5
 
 
SUMMARY OF CHANGES SPONSOR APPROVAL PAGE 
 
Clinical Study Protocol Number:  
 
NSR-RPGR-01 
Protocol Title: 
A Dose Escalation, Phase 1/2 Clinical Trial 
of Retinal Gene Therapy for X-linked 
Retinitis Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) Encoding 
Retinitis Pigmentosa GTPase Regulator 
(RPGR) 
Summary of changes for Protocol:  
 
Version 4.0 
15 Dec 2017 
 
Approved By: 
 
The person listed below is authorised to sign the summary of changes on behalf of NightstaRx 
Ltd. 
 
 
Signed:
Date:
15 DEC 2017
, MD  
 
 
 
 
 
 

AAV8-RPGR 
Protocol: NSR-RPGR-01
Protocol Version 4.0 
15 Dec 2017
 
CONFIDENTIAL
Page 3 of 5
 
 
Amendment 3.0, 15 Dec 2017 
Amendment:  
Updated study design to confirm assessment of Cohort 4 (1 x 1011 gp) as standard, and 
potential Cohorts 5 (2.5 x 1011 gp) and 6 (5 x 1011 gp). 
Rationale: 
To allow wider dose exploration, if appropriate.  
Sections: 
 Protocol synopsis 
 7.3 Dose escalation scheme 
Amendment:  
Updated study design to include additional Visits 10 (Month 18) and 11 (Year 2). 
Rationale: 
To allow longer duration of post-treatment follow-up (24 months in total), in line with 
feedback received from regulatory agencies.  
Sections: 
 Protocol synopsis 
 7.1 Overall study design 
 10.10 Visit 10 and 11 
 17.1 Schedule of study procedures 
Amendment:  
Updated Maximum Tolerated Dose (MTD) cohort eligibility criteria to include patients 
≥10 years of age. 
Rationale: 
To allow inclusion of a wider study population in the MTD cohort, after safety and 
tolerability is first demonstrated in adults, considering X-linked Retinitis Pigmentosa is 
associated with early-onset of symptoms in childhood, and some children as young as 10 
years of age can have significant disease affecting the central macula (i.e. potential 
candidates for gene therapy).  

AAV8-RPGR 
Protocol: NSR-RPGR-01
Protocol Version 4.0 
15 Dec 2017
 
CONFIDENTIAL
Page 4 of 5
 
 
Sections: 
 Protocol synopsis 
 7.5 Discussion of study design and dose selection 
 8.1 Inclusion criteria 
Amendment:  
Updated eligibility criteria to specify that ellipsoid zone at screening must be within the 
borders of the SD-OCT scan.  
Rationale: 
To ensure that participating patients have active disease within the macular region. 
Otherwise, the central reading centre is unable to adequately grade the SD-OCT images, 
which would negatively impact secondary study endpoints. 
Sections: 
 Protocol synopsis 
 8.1 Inclusion criteria 
Amendment:  
Updated Dose Limiting Toxicity (DLT) definition to exclude events related to the surgical 
procedure.  
Rationale: 
From the literature, it is known that the vitrectomy almost always leads to a transient, but 
significant, drop in visual acuity immediately post-operatively. This can be confused with a 
DLT event and therefore clarification is provided in the protocol to ensure only genuine 
cases of DLTs are identified and reported. 
Sections: 
 Protocol synopsis 
 7.2 Dose limiting toxicity 
Amendment:  
Removed several study assessments from specific visits, e.g.:  
 Blood pressure & pulse (Visits 5, 9 and ET) 
 Viral shedding (Visit 6) 

AAV8-RPGR 
Protocol: NSR-RPGR-01
Protocol Version 4.0 
15 Dec 2017
 
CONFIDENTIAL
Page 5 of 5
 
 
 FAF (Visit 4) 
 Triplicate MP and VF (Visits 9 and ET) 
Rationale: 
Following feedback from the central reading center, and several study sites, the utility of 
above assessment at these specific time-points is considered low. 
Sections: 
 10.4-10.6, 10.9 and 10.11 (Visits 4-6, 9 and ET) 
 17.1 Schedule of study procedures  
Amendment: 
Other minor changes throughout document. 
Rationale: 
To improve clarity or correct typographical errors. 
Sections: 
Throughout protocol. 
 

 Phase 1/2 Study of AAV8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 3.0 (amendment 2.0) 
26 May 2017 
 
CONFIDENTIAL 
Page 1 of 5 
 
 
1. 
TITLE PA 
SUMMARY OF CHANGES FOR  
CLINICAL STUDY PROTOCOL  
NSR-RPGR-01  
 
A Dose Escalation, Phase 1/2 Clinical Trial of Retinal Gene 
Therapy for X-linked Retinitis Pigmentosa Using an Adeno-
Associated Viral Vector (AAV8) Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
 
XIRIUS STUDY  
INDICATION: 
 
 
X-linked retinitis pigmentosa  
STUDY PHASE:  
 
1/2 
EUDRACT NUMBER:  
2016-003852-60 
SPONSOR: 
NightstaRx Ltd 
Wellcome Gibbs Building, 215 Euston Road 
London NW1 2BE, UK 
Telephone:  +44 (0) 207 611 2077 
 
SUMMARY OF CHANGES: Protocol Version 3.0 (amendment 2.0) 
 
 
 
 
 
26 May 2017 
 
CONFIDENTIALITY STATEMENT 
This protocol is the property of NightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. Persons 
to whom the information is disclosed must be informed that the information is CONFIDENTIAL 
and may not be further disclosed by them. 
 

 Phase 1/2 Study of AAV8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 3.0 (amendment 2.0) 
26 May 2017 
 
CONFIDENTIAL 
Page 3 of 5 
 
 
Amendment 2.0, 26 May 2017 
Amendment:  
Update inclusion criterion for BCVA in MTD cohort.  
Rationale: 
To allow inclusion of a wider study population into the MTD cohort.  
Sections: 
• Protocol synopsis 
• 7.3 Dose escalation scheme 
• 8.1 Inclusion criteria 
Amendment:  
Low luminance visual acuity assessment and full field stimulus threshold have been added 
as additional assessments. LLVA will be conducted at the same timepoints as EDTRS 
BCVA, FST will be conducted at baseline/screening, month 6, year 1 and Early 
termination visit 
Rationale: 
LLVA and FST tests have a potential to provide additional data to measure changes in 
disease progression over time.  
Sections: 
LLVA 
• Protocol Synopsis 
• 7.1 Overall Study Design 
• 10.1 Visit 1 (Screening/Baseline Visit) 
• 10.3 Visit 3 
• 10.4 Visit 4 
• 10.5 Visit 5 
• 10.6 Visit 6 
• 10.7 Visit 7 
• 10.8 Visit 8 
• 10.9 Visit 9 
• 10.10 Early Termination visit 
• 11.7 Low Luminance Visual Acuity  

 Phase 1/2 Study of AAV8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 3.0 (amendment 2.0) 
26 May 2017 
 
CONFIDENTIAL 
Page 4 of 5 
 
 
• 17.1 Schedule of Procedures 
FST 
• Protocol synopsis 
• 7.1 Overall study design 
• 10.1 Visit 1 (Screening/Baseline Visit) 
• 10.7 Visit 7 
• 10.9 Visit 9 
• 10.10 Early Termination Visit 
• 11.8 Full Field Stimulus Threshold Test  
• 17.1 Schedule of Procedures 
Amendment: 
Remove microperimetry assessment at visit 4.  
Rationale: 
The utility of microperimetry at visit 4 (Day 7 post-op) is expected to be low. 
Sections: 
• 10.4 Visit 4 
• 17.1 Schedule of Procedures 
Amendment: 
Update schedule of procedures to include triplicate testing at screening/baseline, year 1 and 
early termination visit for: EDTRS BCVA, LLVA, microperimetry and visual fields.  
Rationale: 
Following feedback from the central reading center, and several study sites, triplicates will 
improve data quality by mitigating potential learning effects and providing a measure of 
test-retest variability. 
Sections: 
• 10.1 Visit 1 (Screening/Baseline Visit) 
• 10.9 Visit 9 
• 10.10 Early Termination Visit 
• 17.1 Schedule of Procedures 
Amendment: 
Adding corticosteroid compliance review 

 Phase 1/2 Study of AAV8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 3.0 (amendment 2.0) 
26 May 2017 
 
CONFIDENTIAL 
Page 5 of 5 
 
 
Rationale: 
To clarify that corticosteroid compliance will be monitored. 
Sections: 
• 10.2 Visit 2 
• 10.3 Visit 3 
• 10.4 Visit 4 
• 10.5 Visit 5 
Amendment: 
Screening/baseline visit timing changed, from within 4 weeks of Visit 2 (±2 weeks), to 
within 8 weeks of Visit 2 (±2 weeks). 
Rationale: 
To provide more flexibility in scheduling subsequent visits. 
Sections: 
• 10.1 Visit 1 (Screening/Baseline Visit) 
• 17.1 Schedule of Procedures 
Amendment: 
Other minor changes throughout document. 
Rationale: 
To improve clarity or correct typographical errors. 
Sections: 
Throughout protocol. 
 

Phase 1/2 Study of AA V8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 2.0 (amendment 1.0) 
01 Dec 2016 
SUMMARY OF CHANGES FOR 
CLINICAL STUDY PROTOCOL 
NSR-RPGR-01 
A Dose Escalation, Phase 1/2 Clinical Trial of Retinal Gene 
Therapy for X -linked Retinitis Pigmentosa Using an Adeno-
"-
Associated Viral Vector (AA V8) Encoding Retinitis Pigmentosa 
GTPase Regulator (RPGR) 
INDICATION: 
STUDY PHASE: 
EUDRACT NUMBER: 
SPONSOR: 
XIRIUS STUDY 
X-linked retinitis pigmentosa 
112 
2016-003852-60 
NightstaRx Ltd 
Wellcome Gibbs Building, 215 Euston Road 
London NW1 2BE, UK 
Telephone: +44 (0) 207 611 2077 
SUMMARY OF CHANGES: Protocol Version 2.0 (amendment 1.0) 
01 Dec 2016 
CONFIDENTIALITY STATEMENT 
This protocol is the property ofNightstaRx Ltd. It is not to be transmitted, copied or published 
without written permission from NightstaRx and must be kept in a confidential manner. Persons 
to whom the information is disclosed must be informed that the information is CONFIDENTIAL 
and may not be further disclosed by them. 
CONFIDENTIAL 
Page 1 of3 

Phase 112 Study of AA V8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 2.0 (amendment 1.0) 
01 Dec 2016 
SUMMARY OF CHANGES SPONSOR APPROVAL PAGE 
Clinical Study Protocol Number: 
Protocol Title: 
Summary of changes for Protocol: 
Approved By: 
NSR-RPGR-01 
A Dose Escalation, Phase 1/2 Clinical Trial 
ofRetinal Gene Therapy for X-linked 
Retinitis Pigmentosa Using an Adena-
Associated Viral Vector (AA V8) Encoding 
Retinitis Pigmentosa GTPase Regulator 
(RPGR) 
Version 2.0 (amendment 1.0) 
01 Dec2016 
The person listed below is authorised to sign the summary of changes on behalf ofNightstaRx 
Ltd. 
Signed: 
, MD 
 
CONFIDENTIAL 
Date: 
Page 2 of3 

Phase 112 Study of AAV8-RPGR 
Clinical Study Protocol NSR-RPGR-01 
Protocol Version 2.0 (amendment 1.0) 
01 Dec 2016 
Amendment 1.0, 01 Dec 2016 
Amendment: 
Update exclusion criterion 2 to include time frame (3 months), within which subjects are to 
be compliant with the use of barrier contraception. 
Rationale 
To clarify both the time frame (3 months) and that the requirement applies from the time 
subjects receive AA V8-RPGR. 
Sections: 
• 2. Protocol Synopsis 
• 8.2. Exclusion Criteria 
• 1 0.1. Visit 1 (Screening/Baseline Visit) 
• 10.3. Visit 3 (Day 1 Post-Operative Visit) 
CONFIDENTIAL 
Page 3 of3