We present the results of a Phase 2a randomized controlled trial investigating the safety, and secondary endpoints of subretinal rAAV.sFLT-1 gene therapy in patients with active wet age-related macular degeneration (wAMD).
All patients (n = 32), ( ClinicalTrials.gov; NCT01494805), received ranibizumab injections at baseline and week 4, and thereafter according to prespecified criteria. Patients in the gene therapy group (n = 21) received rAAV.sFLT-1 (1 × 10 11 vg). All patients were assessed every 4 weeks to the week 52 primary endpoint.
Ocular adverse events (AEs) in the rAAV.sFLT-1 group were mainly procedure related and self-resolved. All 11 phakic patients in the rAAV.sFLT-1 group showed progression of cataract following vitrectomy. No systemic safety signals were observed and none of the serious AEs were associated with rAAV.sFLT-1. AAV2 capsid was not detected and rAAV.sFLT-1 DNA was detected transiently in the tears of 13 patients. ELISPOT analysis did not identify any notable changes in T-cell response. In the rAAV.sFLT-1 group 12 patients had neutralizing antibodies (nAb) to AAV2. There was no change in sFLT-1 levels in bodily fluids. In the rAAV.sFLT-1 group, Best Corrected Visual Acuity (BCVA) improved by a median of 1.0 (IQR: − 3.0 to 9.0) Early Treatment Diabetic Retinopathy Study (ETDRS) letters from baseline compared to a median of − 5.0 (IQR: − 17.5 to 1.0) ETDRS letters change in the control group. Twelve (57%) patients in the rAAV.sFLT-1 group maintained or improved vision compared to 4 (36%) in the control group. The median number of ranibizumab retreatments was 2.0 (IQR: 1.0 to 6.0) for the gene therapy group compared to 4.0 (IQR: 3.5 to 4.0) for the control group.
Interpretation rAAV.sFLT-1 combined with the option for co-treatment appears to be a safe and promising approach to the treatment of wAMD.
Subretinal injection of rAAV.sFLT-1 was found to be safe in 21 patients with wet age-related macular degeneration.
Visual acuity was maintained in gene therapy treated patients over the 52 week period.
The gene therapy treated group of patients had a trend towards fewer ranibizumab retreatments than the control group.
Wet age-related macular degeneration (wAMD) is a common cause of vision loss in the elderly. We propose to use gene therapy to treat this disease. This study reinforces the findings from our Phase 1 study examining the safety of the delivery of rAAV.sFLT-1 by subretinal injection as a form of treatment of wAMD. The findings from this trial demonstrate that the surgical subretinal administration of rAAV.sFLT-1 has a favorable safety profile and that it can potentially be used in conjunction with current therapies to provide an improved outcome in the treatment of wAMD.