AAVL’s phase-1 data were not as good as some people think. Of the 6 non-control patients (3 in the high-dose arm), only one of them had a VA gain of >=3 lines (15 letters), which is the standard regulatory endpoint in wet AMD.
Moreover, REGN opted not to fork over money for this program on the come, settling instead for a mere right of first negotiation.
From a scientific standpoint, wet AMD is a multifaceted disease that seems ill suited to gene therapy, IMO.