hF.IX expression levels and anti-hF.IX antibody formation after AAV2-hF.IX hepatic gene transfer in rhesus macaques receiving MMF and sirolimus. Time 0 represents baseline samples; dotted vertical line shows the time IS was withdrawn. Each line is representative of one individual animal. All animals received 8 × 10¹² vg/kg of an AAV-2-hF.IX vector infused through the hepatic artery. (A) Plasma human F.IX levels. (B) Plasma anti–human F.IX total IgG levels.