CSL Behring Acquires Rights to Market AMT-061, Gene Therapy for Hemophilia B

CSL Behring has acquired exclusive global rights to commercialize AMT-061, a potential gene therapy for hemophilia B now in a pivotal clinical trial, from its developer uniQure.

Under terms of the agreement, uniQure will receive an upfront payment of $450 million from CSL Behring, and is eligible to additional royalty payments upon the completion of certain regulatory and commercial milestones.

A Phase 3 clinical trial, called HOPE-B (NCT03569891), is assessing the safety and efficacy of a single dose of AMT-061 in 54 people with moderate-to-severe hemophilia B. uniQure will continue as this study’s sponsor, and scale up the potential therapy’s manufacturing to ensure an early commercial supply.

“We are thrilled to enter into this commercialization and license agreement with CSL Behring, an ideal commercial partner with global reach and decades of expertise in hemophilia,” Matt Kapusta, CEO of uniQure, said in a press release.

“We believe that through this arrangement, we are ideally positioned to deliver our innovative gene therapy to the largest number of hemophilia B patients as quickly as possible … [and] expect that it will provide uniQure with significant financial resources to advance and expand our pipeline of gene therapy candidates,” Kapusta added.

AMT-061 is a one-time gene therapy that uses a harmless adeno-associated virus (AAV) vector, called AAV5, to deliver a genetically engineered, patented version the F9 gene — which carries the instructions to make the clotting factor IX (FIX) protein that is missing in people with hemophilia B — to patient’s cells.

This modified gene version, called the Padua variant (FIX-Padua), has been shown to increase the activity of FIX by eight to nine times, and has the potential to reduce or eliminate the need for continuous infusions of FIX (replacement therapy).

Previous data from a Phase 2b trial (NCT03489291) showed that a single dose of AMT-061 led to a stable and sustained FIX activity — with increases reaching up to 50% of what would be considered normal — in all treated patients after one year. Treatment also prevented the occurrence of spontaneous bleeds and the need for preventive treatments in the year following dosing in all patients.

Top-line findings the Phase 3 HOPE-B trial of AMT-061 are expected by year’s end. If positive, they are likely to support a request, in the form of biologics license application (BLA), for the therapy’s approval in the U.S.

“We are exceedingly encouraged by the data we’ve seen on AMT-061. Not only has the treatment option demonstrated robust clinically meaningful responses in FIX activity, but it has also exhibited excellent safety over multiple years of observation,” said Bill Mezzanotte, an executive vice president, head of Research and Development, and chief medical officer of CSL Behring.

By acquiring the global commercial rights of AMT-061, CSL Behring stated that is strengthening and expanding its current gene therapy portfolio for rare diseases, which includes CSL200, an experimental stem cell gene therapy for sickle cell disease.