ssAAV2 hF.IX Subject Dose vg/kg NAB titer1 Peak F.IX (%) Sustained F.IX (%) LFT2 Capsid specific T cells A 8x1010 N/A < 1 < 1 WNL ND B 8x1010 1:2 < 1 < 1 WNL ND C 4x1011 1:2 < 1 < 1 WNL ND D 4x1011 1:11 < 1 < 1 WNL ND G 4x1011 < 1:2 < 1 < 1 < Grade 1 + E 2x1012 1:2 11 < 1 Grade 3 ND F 2x1012 1:17 3 < 1 WNL ND scAAV8 hF.IX Subject Dose vg/kg NAB titer relative units3 Peak F.IX (%) Sustained F.IX (%) LFT2 Capsid specific T cells S1 2x1011 1 2 2 WNL - S2 2x1011 12 2 2 WNL - S3 6x1011 37 3 1-3 WNL + S4 6x1011 1 4 2-3 WNL + S5 2x1012 5 8 3 Grade 3 + S6 2x1012 8 12 8-12 WNL + 1reciprocal dilution anti AAV2 capsid titer, 2Liver function tests (AST/ALT) 3 anti AAV8 capsid titer WNL: within normal limits ND: not done

Table 1: Comparison of ssAAV2 hFIX and scAAV8 hFIX clinical trials.