CSL Behring has shared positive four-year results from a late-stage study of its haemophilia B gene therapy Hemgenix (etranacogene dezaparvovec-drlb).
The ongoing phase 3 HOPE-B trial has been evaluating the long-term durability and safety of a one-time infusion of Hemgenix in adult men with severe or moderately severe cases of the genetic bleeding disorder, with or without pre-existing AAV5 neutralising antibodies.
Affecting an estimated one per every 19,283 male births in the US, haemophilia B results from missing or insufficient levels of blood-clotting factor IX.
Patients with moderate-to-severe cases of the disease typically require life-long prophylactic infusions of factor IX to prevent bleeding episodes.
Hemgenix, which allows eligible patients to continuously produce their own factor IX after a one-time single dose by intravenous infusion, was approved by the US Food and Drug Administration in 2022 to treat adults who use factor IX prophylaxis therapy, have current or historical life-threatening bleeding, or have repeated, serious spontaneous bleeding episodes.
Results presented at this year’s Annual Congress of the European Association for Haemophilia and Allied Disorders showed that 94% of patients remained free of continuous prophylaxis treatment at year four, with no patients returning to continuous prophylaxis between years three and four of HOPE-B.
Mean factor IX activity levels were also sustained at near normal levels of 37% through four years post-treatment, and mean adjusted annualised bleeding rate for all bleeds was reduced by approximately 90% from lead-in to year four.
Andres Brainsky, vice president research and development haematology at CSL, said: “This data continues to instil confidence in the clinical benefits of Hemgenix, highlighting the remarkable impact of this one-time treatment to reduce the frequency of bleeds in people with haemophilia B and improve quality of life by alleviating the burden of ongoing factor IX prophylactic treatment.”
The new data follows the National Institute for Health and Care Excellence’s recommendation of Hemgenix in June.
The health technology assessment agency’s positive opinion, which specifically applies to adults with severe or moderately severe cases without a history of factor IX inhibitors, reversed its previous decision to reject the therapy.