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

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Increases in FIX Activity Sustained at up to 51% of Normal, with Mean FIX of 38% of Normal at Twelve Weeks After Administration

None of the Patients Received Factor Infusions, Reported Bleeding Events or Required Immunosuppression Over a Combined 42 Weeks of Observation

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uniQure N.V. (NASDAQ: QURE), a leading gene therapy company advancing transformative therapies for patients with severe unmet medical needs, today announced updated clinical data in patients treated in the Company’s ongoing Phase IIb 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 (EAHAD) and show that therapeutic levels of Factor IX (FIX) activity continue to be sustained in all three patients up to sixteen weeks after a single administration of AMT-061.* AMT-061 has been granted Breakthrough Therapy Designation by the United States Food and Drug Administration and access to the Priority Medicine (PRIME) regulatory initiative by the European Medicines Agency.

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 (endogenous FIX activity less than one percent) 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 (aPTT) assay performed at a central laboratory.

“We are extremely pleased with these updated data,” stated Robert Gut, M.D., Ph.D., chief medical officer of uniQure. “The study demonstrates AMT-061 has the potential to increase FIX activity into the normal range and continues to be very well tolerated, with no serious adverse events reported and no patients requiring any immunosuppression therapy. We look forward to providing further updates on these patients later in the year at other academic conferences.”

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 (AST), which quickly resolved without any additional treatment or loss of FIX activity. No patient has experienced any material elevation in alanine aminotransferase (ALT) after the administration of AMT-061.

“Our goal with AMT-061 is to give all people living with hemophilia B access to a one-time treatment capable of normalizing FIX activity and eliminating the need for replacement therapy, without the risk of immune responses that require immunosuppression or may lead to a loss of efficacy,” stated Matt Kapusta, chief executive officer of uniQure. “These updated data continue to suggest that AMT-061 may be the first gene therapy able to achieve this goal, and we remain focused on completing enrollment in our ongoing pivotal Phase III study by the end of the year.”

Patients in the Phase IIb study will be followed for 52 weeks to assess FIX activity, bleeding rates and usage of FIX replacement therapy, and will be monitored for five years to evaluate the safety of AMT-061.