Phase 2 Data of Gene Therapy Show Increased Factor IX Activity in Hemophilia B

Steady advancements in hemophilia therapies have drastically improved management of the disease, with breakthrough gene therapies poised to further revolutionize the treatment landscape.

Newly-updated clinical data from a small phase 2b study involving uniQure’s investigational gene therapy for hemophilia B showed promising results, the company announced in a press release. The candidate, AMT-061, is an AAV5-based gene therapy containing a patient-protected Factor IX (FIX)-Padua variant being developed for the treatment of patients with severe and moderately severe hemophilia B.

The data were presented at the Annual Congress of the European Association for Hemophilia and Allied Disorders.

Three patients with severe hemophilia were enrolled in the study and received a single intravenous infusion of 2x10¹³ vc/kg. All patients showed low levels of pre-existing antibodies to AAV5 prior to administration.

According to the data, all 3 patients in the trial demonstrated increasing and sustained FIX levels after the 1-time administration of AMT-061. Additionally, mean FIX activity for all patients at 12 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 16 weeks after administration, FIX activity in the second patient was 25% of normal at 14 weeks after administration, and the third patient achieved FIX activity of 51% of normal at 12 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, according to the study.

Overall, no patients experienced a material loss of FIX activity, reported any bleeding events, or required any infusions of FIX replacement therapy. One patient in the study experienced slight elevations in aspartate aminotransferase, which quickly resolved without additional treatment or loss of FIX activity.

The phase 2b study will continue for 52 weeks to assess FIX activity, bleeding rates, and usage of FIX replacement therapy. Patients will be monitored for 5 years to evaluate the safety of AMT-061, according to uniQure.

“Our goal with AMT-061 is to give all people living with hemophilia B access to a 1-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,” Matt Kapusta, chief executive officer of uniQure, said in a statement. “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 the enrollment in our ongoing pivotal phase 3 study by the end of year.”

The HOPE-B trial, a phase 3 study to evaluate the safety and efficacy of AMT-061, is underway. The study will include approximately 50 adults with severe or moderately severe hemophilia B. For the study, patients will continue to use their current standard-of-care treatment for a 6-month lead-in observational period, followed by a single intravenous administration of AMT-061.

The primary endpoint will be based on the FIX activity level achieved following administration of AMT-061, according to uniQure.

AMT-061 was previously granted Breakthrough Therapy Designation by the FDA.

Reference

uniQure Announces Updated Clinical Data from Phase 2 Study of AMT-061 in Patients with Hemophilia B [news release]. uniQure. http://uniqure.com/investors-newsroom/overview.php. Accessed February 8, 2019.