uniQure announced updated clinical data in patients treated in the company's ongoing Phase 2b study of AMT-061, an investigational AAV5-based gene therapy containing a patent-protected FIX-Padua variant, for the treatment of patients with severe and moderately severe hemophilia B. These data were presented in an oral session at the annual congress of the European Association for Haemophilia and Allied Disorders, or EAHAD, and show that therapeutic levels of Factor IX, or FIX, activity continue to be sustained in all three patients up to sixteen weeks after a single administration of AMT-061. The Phase IIb study of AMT-061 is an open-label, single-dose, single-arm, multi-center trial being conducted in the United States. Three patients with severe hemophilia were enrolled in the study and received a single intravenous infusion of 2x1013 vc/kg. Prior to the administration of AMT-061, all three patients showed low levels of pre-existing antibodies to AAV5 but were not excluded from the trial on that basis. Updated data presented at EAHAD show that all three patients have demonstrated increasing and sustained FIX levels after the one-time administration of AMT-061. Mean FIX activity for the three patients at twelve weeks increased to 38% of normal, exceeding threshold FIX levels generally considered sufficient to eliminate or significantly reduce the risk of bleeding events. The first patient achieved FIX activity of 48% of normal at sixteen weeks after administration. FIX activity in the second patient was 25% of normal at fourteen weeks after administration, and the third patient achieved FIX activity of 51% of normal at twelve weeks after administration. The second and third patients had previously screen-failed and were excluded from another gene therapy study due to pre-existing neutralizing antibodies to a different AAV vector. Reported FIX activity was measured using an activated partial thromboplastin time, or aPTT, assay performed at a central laboratory. No patient in the study has experienced a material loss of FIX activity, reported any bleeding events or required any infusions of FIX replacement therapy. As previously reported, one patient experienced slight elevations in aspartate aminotransferase, or AST, which quickly resolved without any additional treatment or loss of FIX activity. No patient has experienced any material elevation in alanine aminotransferase, or ALT, after the administration of AMT-061.
