Dutch biotech uniQure has treated the first of around three patients due to enroll in its phase 2b dose-confirmation trial of hemophilia B gene therapy AMT-061.
It’s an important milestone for uniQure as it prepares to start the treatment phase of its HOPE-B pivotal study of the gene therapy, which is currently recruiting hemophilia B patients and—according to the company—gives it a chance to be the first to market with a one-off treatment for the disease.
uniQure is in a race with other hemophilia B gene therapy developers, including Spark Therapeutics whose SPK-9001 candidate is heading for phase 3 trials sponsored by development partner Pfizer. Spark and uniQure are currently considered the front runners since rival Shire scrapped its BAX 335 therapy last year.
uniQure’s dosing study is designed to “demonstrate meaningful increases in [Factor IX] activity using the Padua variant and confirm dosing for the HOPE-B pivotal trial initiated this past June,” says Robert Gut, M.D., Ph.D., the biotech’s Chief Medical Officer.
The Padua variant of FIX is much more potent at causing blood clotting than the ‘wild-type’ FIX found in the body, which was used in uniQure’s earlier AMT-060 candidate. The sequence for FIX-Padua is delivered in uniQure’s therapy via an adeno-associated virus type 5 (AAV5) vector.
“The initiation of the AMT-061 dose-confirmation study is an important step toward our goal of advancing a potentially life-changing treatment for patients with hemophilia B,” notes Gut. Top-line data from the study are due before the end of the year.
Around three patients will receive a single intravenous dose of the therapy (2x10^13 vc/kg) and will be followed up for six to eight weeks to make sure FIX activity is being observed as expected. If all goes to plan, treatment will then be able to start in the HOPE-B trial, which aims to recruit around 50 subjects, in the first quarter of 2019.
At the moment, patients enrolled in HOPE-B are being followed for six months to get a baseline value for factor replacement therapy before the gene therapy is administered. In the meantime, uniQure is busy producing clinical batches of the gene therapy at its Lexington, Massachusetts, manufacturing facility.
Clinical results to date with hemophilia B gene therapies have produced some stellar outcomes, including the elimination of bleeding episodes in some patients as well as the need for treatment with recombinant clotting factors for a year or more after dosing.