XLRP is characterized by progressive deterioration of the visual field. Octopus 900 full-field static perimetry and MAIA microperimetry were employed to determine change in retinal sensitivity following intervention.Perimetry is a sensitive standard-of-care measure of retinal function that reproducibly determines retinal sensitivity both cross-sectionally and longitudinally, thereby accurately defining disease progression over time.At the nine-month analysis (Octopus 900 static perimetry), compared to baseline:
- Six out of seven patients in the low (n=3) and intermediate (n=4) dose cohorts demonstrated improvement or stability in retinal sensitivity in the treated eye
- Improvements in treated eyes compared to baseline were sustained or further improved compared to the six-month analysis in the low and intermediate dose cohorts
- In each of the low and intermediate dose cohorts, significant improvement was observed between treated and untreated eyes in retinal sensitivity
- At the six-month timepoint, improvements in retinal sensitivity were not observed in the high dose cohort. Perimetry assessment was not carried out in the high dose cohort at the nine-month timepoint due to protocol revision implemented to align with the dose-expansion cohort assessment schedule.
At nine-month analysis, compared to baseline:
- Five of six patients demonstrated improvement in walk time for the treated eye at lux levels 1, 4 or 16
- Significant improvement was observed between treated and untreated eyes in the low and intermediate dose cohorts (n=6) at 1 lux, -16.1 seconds (90% CI: 9.91, 22.1) and 4 lux, -3.71 seconds (90% CI: 2.83, 4.96); with the greatest improvement at the lowest light level (1 lux)
- Vision-guided mobility assessment was not carried out in the high dose cohort at the nine-month timepoint due to protocol revision implemented to align with the dose-expansion cohort assessment schedule
Safety data obtained to date continue to suggest AAV-RPGR is well-tolerated. No dose-limiting events occurred. As previously presented, signs of inflammation were observed in two out of three patients in the high dose cohort, which may have been associated with decreased activity of the AAV-RPGR treatment in these patients. Inflammation was effectively managed with an extended steroid protocol.Based on the safety and efficacy profile demonstrated to date, the low and intermediate doses are being evaluated in the ongoing randomized, controlled expansion portion of the Phase 1/2 study, which completed enrollment in the first half of 2020. As previously disclosed, MeiraGTx and development partner Janssen plan to advance AAV-RPGR into a Phase 3 pivotal study, called the Lumeos clinical trial.
