What the trial was testing
The trial enrolled 15 patients with hemophilia. The study was sponsored by Pfizer and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was initial testing (phase 2). 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
The annual bleeding rate dropped from 11 episodes per year to less than 1 after gene therapy.
The New England journal of medicine · 2017 · NCT02484092
These findings — that nine patients had no bleeding episodes after receiving the one-time gene therapy treatment — were published in the The New England journal of medicine and represent the headline result of the study.
Researchers tracked outcomes across 15 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
This was an initial testing study with 10 patients. The gene therapy (fidanacogene elaparvovec) later received FDA approval in 2024 under the brand name Beqvez for adults with moderate to severe hemophilia B. Ask your doctor if this treatment might be right 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
The Efficacy and Safety of ZS801 in Chinese Hemophilia B Patients.
A non-randomized, open-label study to evaluate the safety, kinetics and efficacy of a single intravenous infusion of ZS801 in hemophilia B subjects with endogenous FIX ≤2%.
Tight Control of Treatment Adherence and Efficacy by Telemedicine for an Improved Personalized Management of Patients With Hemophilia
In patients with haemophilia, close monitoring of bleeding with optimal adherence to treatment, a personalised treatment programme and the possibility of early diagnosis of haemarthrosis are essential. The TEMPO project will help advance the state of the art in optimal adherence, rigorous monitoring, and accurate and early diagnosis and management of haemarthrosis by collecting and integrating big data in order to personalise the treatment regimen for each patient, as envisaged by the current model of personalised medicine.