uniQure Announces Updated Clinical Data from Phase IIb Study of AMT-061 in Hemophilia B Patients

LEXINGTON, Mass. and AMSTERDAM, the Netherlands — uniQure N.V. (NASDAQ: QURE), a leader in gene therapy, has announced updated clinical data from its ongoing Phase IIb study of AMT-061, an investigational AAV5-based gene therapy for treating severe and moderately severe hemophilia B. The data, presented at the Hemostasis & Thrombosis Research Society (HTRS) 2019 Scientific Symposium, indicate sustained clinically significant elevations of Factor IX (FIX) activity in all three patients up to six months post-administration.

Study Details and Findings The Phase IIb study is an open-label, single-dose, single-arm, multi-center trial conducted in the United States. Three patients with severe hemophilia (endogenous FIX activity less than one percent) received a single intravenous infusion of 2x1013 vc/kg. Despite low levels of pre-existing neutralizing antibodies to AAV5, none were excluded from the trial. Patients will be followed for 52 weeks to assess FIX activity, bleeding rates, and usage of FIX replacement therapy, with a five-year safety monitoring period.

Updated data show increasing and sustained FIX levels post-AMT-061 administration, with two patients achieving FIX activity in the normal range. Mean FIX activity at six months was 47% of normal, with individual patient levels at 51%, 33%, and 57% of normal. Notably, two patients previously excluded from another gene therapy study due to pre-existing neutralizing antibodies to a different AAV vector showed no loss of FIX activity, no bleeding events, and no need for FIX replacement therapy infusions through six months.

Safety and Future Directions Through six months of follow-up, no serious adverse events, thrombotic events, or FIX inhibitors were reported. uniQure aims to make AMT-061 available to hemophilia B patients rapidly, focusing on completing enrollment in the ongoing pivotal Phase III study by year-end. The goal is to provide a one-time treatment capable of normalizing FIX activity and eliminating the need for replacement therapy, without the risk of immune responses requiring immunosuppression.

About AMT-061 and uniQure AMT-061 utilizes an AAV5 viral vector carrying the patent-protected Padua variant of Factor IX (FIX-Padua). uniQure holds multiple patents in the United States and Canada for treating bleeding disorders using AAV gene therapy with the FIX-Padua variant. The company is advancing a pipeline of gene therapies for severe genetic diseases, leveraging its validated technology platform.