Abstract
Purpose :
Recent advances in gene augmentation therapy with voretigene neparvovec have demonstrated significant improvements in the functional visual of patients with RPE65 mutation-associated inherited retinal dystrophy.
Whilst the novel primary endpoint from the phase III trial was the change in multi luminance mobility test (MLMT) score from baseline at 12 months, legal blindness status in many countries is based on an assessment of the patients' visual acuity (VA) and/or visual field (VF).
The aim of this analysis was therefore to evaluate the proportion of patients in the phase III trial that would have fulfilled the eligibility criteria for legal blindness in Germany, before and after treatment with voretigene neparvovec.
Methods :
Using VA and VF data from phase III trial, patients were classified as legally blind based on definitions of legal blindness in Germany:
Better seeing eye has a VA of 1/50 on the Snellen chart (1.7 LogMAR) or worse (independent of VF)
Either eye with a VF of 5° (120 total sum of degrees) or less (independent of VA)
The proportion of patients moving from legally blind to non-blind status after treatment with voretigene neparvovec was assessed up to 3 years of follow-up.
Results :
Of the 29 patients receiving voretigene neparvovec in the phase III study (original intervention and delayed intervention group), 11 (38%) were considered legally blind according to the German definition.
One year after receiving treatment, 8 (73%) patients no longer fulfilled the criteria for legal blindness. Only 3 patients remained legally blind.
The proportion of non-legally blind patients in the phase III trial increased from 62% at baseline to 90% at year 1, which was maintained up to year 3 (Figure 1).
At 1-year follow-up of the delayed intervention group (pre-intervention), one patient out of seven turned legally blind according to the German definition, and patients who were legally blind at screening, remained blind (n=2).
Conclusions :
According to the German definition of legal blindness, 73% of the patients in the phase III trial moved from blind to non-blind status, one year after treatment with voretigene neparvovec. These findings mirrored the improvements on patients’ functional vision in phase III trial, where 72% of patients achieved the maximum MLMT score
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.