OBJECTIVE
To determine the effects of escalating doses of AAV2(Y444,500,703F)-P1ND4v2 in patients with LHON caused by the G11778A mutation in mitochondrial DNA.
DESIGN
Prospective open-label, unilateral single-dose, intravitreal injection of AAV2(Y444,500,703F)-P1ND4v2 per subject in a phase I clinical trial study initiated in 2014.
PARTICIPANTS
Fourteen patients with visual loss and mutated G11778A mitochondrial DNA.
INTERVENTION
Intravitreal injection with the gene therapy vector AAV2(Y444,500,703F)-P1ND4v2 into one eye. Six participants with chronic bilateral visual loss greater than 12 months (Group I), 6 participants with bilateral visual loss less than 12 months (Group II) and 2 participants with unilateral visual loss (Group III) were treated. Nine patients had at least 12 months of follow-up. Clinical testing included ETDRS visual acuity, visual fields, OCT, PERG and neuro-ophthalmic examinations. GEE methods were used for longitudinal analyses.
PRIMARY OUTCOME MEASURE
Loss of visual acuity.
RESULTS
For Groups I and II, month 12 average acuity improvements with treatment relative to baseline were 0.24 logMAR. Fellow eyes had a 0.09 logMAR improvement. A post-hoc comparison found that at month 12, the difference between study eye minus fellow eye improvement in Group II patients of 0.53 logMAR was greater than that observed in our prior acute natural history patients of 0.21 logMAR (p=0.053). At month 18, the difference between study eye minus fellow eye improvement in our acute Group II gene therapy patients of 0.96 was greater than that observed in our prior acute natural history patients (0.17 logMAR) p<0.001. Two patients developed asymptomatic uveitis that resolved without treatment. OCT of treated eyes had an average temporal RNFL thickness of 54 μm prior to injection and 55 μm at month 12. For fellow eyes prior to injection it was 56 μm dropping to 50 μm at month 12, p = 0.013. GEE suggested that PERG amplitudes worsened more in treated eyes than in fellow eyes by about 0.05 uV (p exchangeable = 0.009). No difference between eyes in outcomes of other visual function measures was evident.
CONCLUSIONS
Allotopic gene therapy for LHON at low and medium doses appears safe and does not damage the temporal RNFL opening the door for testing of the high dose next.