The US FDA has approved CSL's HEMGENIX (etranacogene dezaparvovec-drlb) as the first and only one-time gene therapy for appropriate adults with haemophilia B.
The Australian TGA granted HEMGENIX orphan designation in September and the company confirmed that it will seek market registration in due course.
HEMGENIX has been approved in the US for the treatment of adults with haemophilia B who currently use factor IX prophylaxis therapy, or have current or historical life-threatening haemorrhage or have repeated, serious spontaneous bleeding episodes.
The company said that in an ongoing clinical trial, HEMGENIX reduced the rate of annual bleeds and 94 per cent of patients discontinued factor IX prophylaxis and remained prophylaxis-free.
"As part of our promise to patients, CSL is committed to delivering innovative and groundbreaking solutions to address unmet medical needs, and we are proud to introduce the next wave of breakthrough medicines for people living with hemophilia B," said CSL CEO and managing director Paul Perreault.
"We recognise and thank all trial participants, scientists and investigators - without whom this important achievement would not have been possible - and look forward to seeing the positive impact of HEMGENIX on the haemophilia B community."
Haemophilia B is a rare, lifelong bleeding disorder caused by a single gene defect, resulting in insufficient production of factor IX, a protein primarily produced by the liver that helps blood clots form.
Treatments for moderate to severe haemophilia B include prophylactic infusions of factor IX replacement therapy to temporarily replace or supplement low levels of blood-clotting factor. The therapies are effective but patients are required to adhere to a strict and lifelong infusion schedule.
They may also still experience spontaneous bleeding episodes as well as limited mobility, joint damage or severe pain as a result of the disease.
"For appropriate patients, HEMGENIX allows people living with haemophilia B to produce their own factor IX, which can lower the risk of bleeding," said CSL.
"We are thrilled to witness this milestone in hemophilia B treatment," shared Kim Phelan, chief operating officer of The Coalition for Haemophilia B. "Over the years we have seen a variety of advancements for the hemophilia community, but gene therapy is the first treatment option to offer those living with hemophilia B--and caregivers--the possibility of freedom from the need for regular, ongoing infusions."
CSL said the FDA approval is supported by results from the ongoing HOPE-B trial. It is the largest gene therapy trial in hemophilia B to date.
It said that results from the study demonstrated that HEMGENIX allowed patients to produce mean factor IX activity of 39 per cent at six months and 36.7 per cent at 24 months post-infusion.
"Seven to 18 months post-infusion, the mean adjusted annualised bleeding rate (ABR) for all bleeds was reduced by 54 per cent compared to the six-month lead-in period on factor IX prophylactic replacement therapy (4.1 to 1.9)," it said.
"In addition, 94 per cent (51 out of 54) of patients treated with HEMGENIX discontinued use of prophylaxis and remained free of previous continuous routine prophylaxis therapy. The most common side effects were liver enzyme elevations, headache, elevated levels of a certain blood enzyme, flu-like symptoms, infusion-related reactions, fatigue, nausea and feeling unwell."
"HEMGENIX is unique in its approach to increasing mean factor IX activity and hemostatic protection in those with haemophilia B, and today's approval could fundamentally transform the treatment paradigm for this life-long condition," said Dr Steven Pipe, Professor and the Laurence A. Boxer Research Professor of Pediatrics and Professor of Pathology at the University of Michigan and a lead investigator in the HOPE-B study.
"As a clinician, I look forward to being able to provide a new treatment option that may help patients treated with HEMGENIX become free from the regular infusion schedule that many people living with haemophilia B rely on to protect them from the debilitating effects of the condition."
The multi-year clinical development program for HEMGENIX was led by uniQure and sponsorship of the clinical trials transitioned to CSL after it acquired global rights to commercialise the treatment.
"Today's approval of the world's first gene therapy for hemophilia B is an historic achievement based on more than a decade of research and clinical development," said Matt Kapusta, CEO of uniQure. "We have always believed that gene therapy had the potential to provide transformative benefits to people living with hemophilia B and are excited that the hemophilia community will have a new, safe and effective treatment option available to them."
CSL said HEMGENIX is still currently under assessment by other regulatory agencies.
