UniQure Says Hemophilia B Gene Therapy Raises FIX Activity up to 54 Percent of Normal

Investigators presented updated clinical data from UniQure’s ongoing phase 2b study of AMT-061, its experimental gene therapy for patients with severe and moderately severe hemophilia B, that showed factor IX activity in patients reached up to 54 percent of normal.

The company reported that patients, at 36 weeks after a one-time administration of AMT-061, had mean factor IX (FIX) activity of 45 percent of normal. 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.

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 (FIX-Padua). The pivotal phase 3 HOPE-B trial of AMT-061 is currently enrolling patients and UniQure plans to complete enrollment by the end of this year.

“These updated data continue to show that a single administration of AMT-061 is well-tolerated and has the potential to increase FIX activity into the normal range for people living with hemophilia B,” said Matt Kapusta, CEO of UniQure. “We continue to be very pleased with these results, which as of this data report show durable increases in FIX activity with no bleeds and no requirement for infusions of FIX replacement therapy or immunosuppression.”

UniQure also presented up to 3.5 years of follow-up data from the phase 1/2 trial of AMT-060, its first-generation gene therapy for the treatment of hemophilia B. The data were presented at the International Society on Thrombosis and Haemostasis Congress in Melbourne, Australia.

In the ongoing phase 1/2 study of AMT-060, all 10 patients continue to show long-term meaningful clinical impact, including sustained increases in FIX activity and improvements in their disease state as measured by reduced usage of FIX replacement therapy and decreased bleeding frequency. At up to 3.5 years of follow-up, AMT-060 continues to be safe and well-tolerated, with no new serious adverse events and no development of inhibitors since the last reported data.

All five patients in the second dose cohort continue to be free of routine FIX replacement therapy at up to three years after treatment. During the last 12 months of observation, the mean annualized bleeding rate was 0.7 bleeds, representing an 83 percent reduction from the year prior to treatment.

During this same period, the usage of FIX replacement therapy declined 96 percent compared to the year prior to treatment. Steady-state mean yearly FIX activity at three years was 7.9 percent, as compared to 7.1 percent in the first year and 8.4 percent in the second year.

AMT-060 is UniQure’s first-generation gene therapy, consisting of an AAV5 vector carrying a gene cassette with the wild-type FIX gene. Data from this phase 1/2 trial of AMT-060 will be part of the regulatory submission for marketing approval of AMT-061.

“The Phase 1/2 study of AMT-060 continues to demonstrate the impressive long-term safety and tolerability of UniQure’s gene therapy platform in hemophilia B,” said Frank Leebeek, of the Erasmus University Medical Center in Rotterdam, the Netherlands. “We have now demonstrated evidence of durable clinical benefits, including sustained FIX activity, improved disease phenotype and substantial reductions in spontaneous bleeds for up to 3.5 years after administration.”

Photo: Matt Kapusta, CEO of UniQure

Author: Rare Daily Staff