What the trial was testing
The EXPLORER4/EXPLORER5 enrolled 36 patients with hemophilia. The study was sponsored by Novo Nordisk A/S 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
Patients on the daily injection had an estimated 3 to 7 bleeding episodes per year, down from their usual rates.
Blood · 2019 · NCT03196297
These findings — that far fewer bleeds than patients usually experience without daily prevention — were published in the Blood and represent the headline result of the study.
Researchers tracked outcomes across 36 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 treatment is still in mid-stage testing and not yet FDA-approved. If you have hemophilia and struggle with frequent bleeds despite current treatments, ask your doctor whether there are open trials for this injection or similar options. The results were strong enough that all participants chose to keep using it in the extended study.
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
ATHN Transcends: A Natural History Study of Non-Neoplastic Hematologic Disorders
In parallel with the growth of ATHN's clinical studies, the number of new therapies for all blood disorders is increasing significantly. Some of the recently FDA-approved therapies for congenital and acquired hematologic conditions have not yet demonstrated long-term safety and effectiveness beyond the pivotal trials that led to their approval. In addition, results from well controlled, pivotal studies often cannot be replicated once a therapy has been approved for general use.2,3,4,5 In 2019 alone, the FDA has issued approvals for 24 new therapies for congenital and acquired hematologic conditions.6 In addition, almost 10,000 new studies for hematologic diseases are currently registered on www.clinicaltrials.gov.7 With this increase in potential new therapies possible, it is imperative that clinicians and clinical researchers in the field of non-neoplastic hematology have a uniform, secure, unbiased, and enduring method to collect long-term safety and efficacy data. As emphasized in a recently published review, accurate, uniform and quality national data collection is critical in clinical research, particularly for longitudinal cohort studies covering a lifetime of biologic risk.8
World Bleeding Disorders Registry
The WBDR is an international observational disease registry of patients with hemophilia. It will provide a platform for a network of hemophilia treatment centres (HTCs) around the world to collect uniform and standardized patient data and guide clinical practice. With informed consent from the patient, the WBDR stores anonymous data about the person's disease, such as hemophilia type and severity, symptoms, and treatment.