A Clinical Trial of Retinal Gene Therapy for X-linked Retinitis Pigmentosa Using BIIB112 (XIRIUS)

DLTs are defined as any of the following events considered to be related to AAV8-RPGR: Sustained decrease in best-corrected visual acuity (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); Any clinically significant retinal damage observed that is not directly attributed to complications of surgery; Any clinically relevant suspected unexpected serious adverse reaction, with the exception of vision loss or vision threatening.

An AE is any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

MAIA microperimetry assessment was measured in dB using a 10-2 grid of 68 points. Each point was labeled as '< 0', '0', or a positive integer. The point labeled as '< 0' was assigned a value of '-1' by MAIA in the calculation. Improvement in Retinal Sensitivity in center grid was defined as an increase from baseline of 7 or more decibels in any 5 or more points out of the 16 central points.

An AE is any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

MAIA microperimetry assessment was measured in dB using a 10-2 grid of 68 points. Each point was labeled as '< 0', '0' or a positive integer. The point labeled as '< 0' was assigned a value of '-1' by MAIA in the calculation. Improvement in Retinal Sensitivity in center grid was defined as an increase from baseline of 7 or more decibels in any 5 or more points out of the 16 central points.

MAIA microperimetry assessment was measured in dB using a 10-2 grid of 68 points. Each point was labeled as '< 0', '0' or a positive integer. The point labeled as '< 0' was assigned a value of '-1' by MAIA in the calculation. Improvement in Retinal Sensitivity in whole grid was defined as an increase from baseline of 7 or more decibels in any 5 or more points of the grid as a whole (68 points).

MAIA microperimetry assessment was measured in dB using a 10-2 grid of 68 points. Each point was labeled as '< 0', '0' or a positive integer. The point labeled as '< 0' is assigned a value of '-1' by MAIA in the calculation. Improvement in Retinal Sensitivity in center grid was defined as an increase from baseline of 7 or more decibels in any 5 or more points out of the 16 central points. Here negative values indicate a decline in retinal sensitivity.

MAIA microperimetry assessment was measured in dB using a 10-2 grid of 68 points. Each point was labeled as '< 0', '0' or a positive integer. The point labeled as '< 0' is assigned a value of '-1' by MAIA in the calculation. Improvement in Retinal Sensitivity in whole grid was defined as an increase from baseline of 7 or more decibels in any 5 or more points of the grid as a whole (68 points). Here negative values indicate a decline in retinal sensitivity.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

BCVA was assessed using the ETDRS VA chart. Initially, letters were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. BCVA was to be reported as number of letters read correctly by the subject. An increase in the number of letters read correctly means that vision has improved.

LLVA was 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 were read at a distance of 4 meters from the chart. If <20 letters were read at 4 meters, testing at 1 meter was performed. LLVA was reported as number of letters read correctly by the subject.

Spectral Domain Optical Coherence Tomography (SD-OCT) was used to assess change in central ellipsoid area.

SD-OCT was used to assess change in central horizontal ellipsoid width. Here negative values indicate decline in central horizontal ellipsoid width.

Fundus Autofluorescence was used to assess change in total area of preserved autofluorescence and distance from foveal center (FC) to nearest border of preserved autofluorescence.

Fundus Autofluorescence was used to assess change in distance from foveal center (FC) to nearest border of preserved autofluorescence.

Visual field testing was performed to assess change in volume of 30-degree hill vision. Reliability Factor (RF)=number of false positive responses + number of false negative responses/number of false positive presentations + number of false negative presentations*100. If there are 0 responses, then RF value=0. RFpositive=number of false positive responses/number of false positive presentations*100. If RF≤ 20% measurement is considered reliable. If 20% < RF ≤ 25% and RFpositive ≤ 10% measurement is also considered reliable. Otherwise if 20% < RF ≤ 25% and RFpositive > 10%, or RF > 25%, measurement is not reliable.

Visual field testing was performed to assess change in volume of full field hill vision. Reliability Factor (RF)=number of false positive responses + number of false negative responses/number of false positive presentations + number of false negative presentations*100. If there are 0 responses, then RF value=0. RFpositive=number of false positive responses/number of false positive presentations*100. If RF≤ 20% measurement is considered reliable. If 20% < RF ≤ 25% and RFpositive ≤ 10% measurement is also considered reliable. Otherwise if 20% < RF ≤ 25% and RFpositive > 10%, or RF > 25%, measurement is not reliable.

Change in contrast sensitivity (CS) was assessed by Pelli-Robson chart which uses a single large letter size (20/60 optotype), with contrast varying across groups of letters. Chart uses letters (6 per line), arranged in groups whose contrast varies from high to low. Subjects read the letters, starting with the highest contrast, until they are unable to read two or three letters in a single group. Each group has three letters of the same contrast level, so there are three trials per contrast level. Subject is assigned a score based on the contrast of the last group in which two or three letters were correctly read. Score is a measure of the subject's log contrast sensitivity ranging from 0-2.25, with 0 being no letters read, and 2.25 being all letters read. Total CS score = [(total # letters correct - 3) x 0.05].

Visual field testing was performed to assess change in volume of 30-degree hill vision. Reliability Factor (RF)=number of false positive responses + number of false negative responses/number of false positive presentations + number of false negative presentations*100. If there are 0 responses, then RF value=0. RFpositive=number of false positive responses/number of false positive presentations*100. If RF≤ 20% measurement is considered reliable. If 20% < RF ≤ 25% and RFpositive ≤ 10% measurement is also considered reliable. Otherwise if 20% < RF ≤ 25% and RFpositive > 10%, or RF > 25%, measurement is not reliable. Here negative values indicate decline in the volume of 30-degree hill vision.

Visual field testing was performed to assess change in volume of full field hill vision. Reliability Factor (RF)=number of false positive responses + number of false negative responses/number of false positive presentations + number of false negative presentations*100. If there are 0 responses, then RF value=0. RFpositive=number of false positive responses/number of false positive presentations*100. If RF≤ 20% measurement is considered reliable. If 20% < RF ≤ 25% and RFpositive ≤ 10% measurement is also considered reliable. Otherwise if 20% < RF ≤ 25% and RFpositive > 10%, or RF > 25%, measurement is not reliable. Here negative values indicate decline in volume of full field hill vision.