What the trial was testing
The XTEND-1 enrolled 159 patients with hemophilia. The study was sponsored by Bioverativ, a Sanofi company and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.
What the results showed
Bleeding episodes dropped 77% with once-weekly efanesoctocog alfa compared to previous prevention treatment.
The New England journal of medicine · 2023 · NCT04161495
These findings — that patients had three-quarters fewer bleeds per year compared to their previous treatment — were published in the The New England journal of medicine and represent the headline result of the study.
Researchers tracked outcomes across 159 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.
What this means for patients
For patients with hemophilia, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.
What you can do now
Efanesoctocog alfa is FDA-approved and sold as Altuviiio. It's given once a week instead of the more frequent injections many hemophilia A treatments require. Ask your doctor if this extended-protection option might work for you.
Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.
Open hemophilia trials
A Clinical Study to Evaluate the Effects of NXT007 Compared to Factor VIII Prophylaxis in Participants With Hemophilia A
The purpose of this study is to evaluate the efficacy, safety, pharmacokinetics and pharmacodynamics of NXT007 prophylaxis compared with Factor VIII (FVIII) prophylaxis in participants with severe or moderate congenital hemophilia A without FVIII inhibitors. The study will include people aged ≥12 years old who have been on FVIII prophylaxis treatment prior to study entry.
Liver Biopsy In Haemophilia Gene Therapy
To perform a liver biopsy in haemophilia A and B patients with endogenous FVIII:C/FIX:C expression at \>1% any time after gene transfer following AAV mediated gene transfer. This is to obtain tissue for analysis, to understand if FIX/FVIII transgenic protein expression is mediated by AAV proviral DNA that is integrated into the host cell DNA or if stable expression in humans is mediated by episomal maintained AAV genome.