uniQure Presents New Clinical Data in Hemophilia B Patients Demonstrating Therapeutic Efficacy of AAV5 Gene Therapy in the Presence of Pre-Existing Neutralizing Antibodies

-- Findings Further Support Expanding the Eligibility of AAV5 Gene Therapies to Nearly All Patients with Hemophilia B --

LEXINGTON, Mass. and AMSTERDAM, the Netherlands, July 11, 2017 (GLOBE NEWSWIRE) -- uniQure N.V. (NASDAQ:QURE), a leading gene therapy company advancing transformative therapies for patients with severe medical needs, today presented new clinical data demonstrating that the presence of pre-existing anti-AAV5 neutralizing antibodies (NABs) does not predict the potential efficacy of AAV5-mediated gene transfer in patients with hemophilia B. Clinically meaningful factor IX (FIX) activity levels from the ongoing Phase I-II trial of AMT-060 were observed at NAB titers up to 1:341, determined as corresponding up to the 90th percentile of a healthy control population. NABs were quantified in the blood sera of these patients using a highly sensitive assay. These clinical data were presented today in a poster presentation at the 26th Biennial Congress of the International Society on Thrombosis and Hemostasis (ISTH), taking place this week in Berlin, Germany.

The presence of pre-existing NABs to adeno-associated virus (AAV) vectors has long posed a critical challenge for the clinical application of gene therapies, as patients who currently screen positive for NABs are generally excluded from treatment. Researchers from uniQure recently presented data in non-human primates suggesting that AAV5 could successfully mediate gene transfer in the presence of NABs at levels as high as 1:1031.   

In a poster presentation at the ISTH meeting, a re-analysis was described of pre-gene transfer screening samples from the 10 patients who have been treated in the ongoing Phase I/II trial of AMT-060 for hemophilia B. The patients had tested negative for pre-existing anti-AAV5 NAbs using a green fluorescent protein-based (GFP) assay before receiving treatment. These samples were later re-assessed using a highly sensitive luciferase-based (LUC) NAB assay.  Anti-AAV5 NABs were detected retrospectively in three patients who had been treated with the low dose (5x1012 gc/kg) of AMT-060. However, all three patients presented increases in FIX expression and, especially, the patient with the highest NAB level (titer 1:341) had the highest FIX-activity (steady-state FIX 6.8% of normal; latest FIX measurement 10.7% of normal) among all five patients treated in the low-dose cohort. None of the three patients who tested positive for NAB titers, experienced over time elevations in liver enzymes post gene transfer, FIX activity loss, or clinically relevant T-cell responses to the capsid.

"These clinical data show that hemophilia B patients presenting with neutralizing antibodies may be considered eligible for AAV5-mediated gene transfer," stated Matthew Kapusta, chief executive officer at uniQure. "This development potentially expands the applicability of AAV5 gene therapies to nearly all hemophilia B patients. We believe these factors contribute to making AAV5 a potential best-in-class vector for delivering gene therapies more effectively and safely to a greater portion of patients in need of treatment."