UniQure’s Late-Stage Hemophilia B Gene Therapy Study Fully Enrolled

Rare Daily Staff

Photo: Matt Kapusta, CEO of UniQure.

UniQure said its late-stage study of etranacogene dezaparvovec, its gene therapy for hemophilia B, is fully enrolled ahead of schedule.

The pivotal phase 3 HOPE-B Trial has enrolled 56 patients. The company said it may enroll up to six additional patients before the end of September due to the high level of interest in the study. The study had been expected to reach its full enrollment by year-end.

Hemophilia B is a rare, genetic, and severe clotting disorder where patients have a missing or defective clotting protein FIX, resulting in possibly severe or spontaneous bleeding. AMT-061 consists of an AAV5 viral vector carrying a gene cassette with the Padua variant of FIX. Padua refers to a spontaneous mutation that was discovered to significantly increase the expression of factor IX.

The study’s primary endpoint is the assessment of FIX activity 26 weeks after dosing. Secondary endpoints include annualized bleeding rate (ABR) and usage of FIX replacement therapy over a 52-week time frame, as well as other efficacy and safety aspects. Post-treatment, patients will be followed for five years.

Patients enrolled in the HOPE-B pivotal trial will be tested for the presence of pre-existing neutralizing antibodies to AAV5 but will not be excluded from the trial based on their titers. Previous studies performed by UniQure suggest that AAV5-based gene therapies may be viable treatments for at least 97 percent of patients.

The study is being conducted at 39 clinical sites across 9 countries. UniQure expects to share topline data from the trial next year.

The HOPE-B study builds on the success of the interim 36-week results of the company’s ongoing phase 2b study of etranacogene dezaparvovec, which demonstrated that a single administration of the experimental gene therapy resulted in sustained increases in factor IX (FIX) levels up to 54 percent of normal, and a mean FIX level of 45 percent of normal.

During that time, no patient reported any bleeding events or required any infusion of FIX replacement therapy for bleeds or experienced any material loss of FIX activity. The company said ongoing study of phase 1/2 study of AMT-060, the Company’s first-generation gene therapy for the treatment of hemophilia B, demonstrated that all 10 patients continue to show sustained and stable increases in FIX activity and long-term clinical benefits at up to 3.5 years of observation.

Etranacogene dezaparvovec has won Breakthrough Therapy designation from the U.S. Food and Drug Administration and access to Priority Medicines (PRIME) regulatory initiative from the European Medicines Agency.

“We are extremely pleased to reach this important milestone in our ongoing development of etranacogene dezaparvovec, which we believe has the potential to be the first and best-in-class gene therapy for patients with hemophilia B,” stated Matt Kapusta, CEO of UniQure.