Pfizer Inc. announced the positive results of a phase 3 study comparing a prophylaxis regimen of BeneFIX Coagulation Factor IX (Recombinant) 100 IU/kg once-weekly to on-demand treatment in people with moderately severe to severe hemophilia B.

The top-line results of the study showed that the primary study endpoint was met and hemophilia B patients taking once-weekly BeneFIX (100 IU/Kg) showed a statistically significant reduction in the annualized bleeding rate (ABR) (P < 0.0001) relative to on-demand treatment with BeneFIX.

In the study, the median ABR value, a commonly used measure of efficacy for prophylaxis regimens in hemophilia, was 2.0 for the prophylaxis regimen, compared to 33.6 for the on-demand regimen, representing a 94% decrease in bleeding rates. The mean ABR value was 3.6 for the prophylaxis period, compared to 32.9 for the on-demand treatment, which represents a reduction of 89% (P < 0.0001).

“These results are important because they add to the growing body of clinical evidence showing that prophylaxis treatment has the potential to reduce the number of bleeds in a year, the most critical factor in hemophilia management,” said Steven J. Romano, M.D., senior vice president and Medicines Development Group Head, Global Innovative Pharmaceuticals, Pfizer Inc. “Pfizer remains committed to the research and development of new and innovative products for the hemophilia community.”

Study results also showed that prophylaxis treatment significantly reduced both spontaneous and traumatic ABR compared to on-demand treatment with BeneFIX. The median spontaneous ABR value was 1.0 for the prophylaxis regimen, compared to 22.4 for the on-demand regimen, and the median traumatic ABR value was 1.0 for the prophylaxis period, compared to 4.1 for the on-demand treatment. In addition to meeting the primary endpoint, the secondary study endpoints showed that none of the 1,254 prophylaxis infusions administered during the study were associated with a less than expected therapeutic effect (LETE) occurrence, which was defined as a spontaneous bleed occurring within 48 hours of a prophylaxis infusion. The majority (82.1%) of bleeding episodes in the prophylaxis arm were resolved after one infusion.

Adverse events observed in the study, for both the prophylaxis and on-demand periods, were consistent with the known adverse event profile of BeneFIX. The most common adverse events reported during the prophylaxis treatment period were arthralgia (20%), upper respiratory infection (20%), toothache (20%), pyrexia (16%), headache (16%), pharyngitis (12%), back pain (12%) and local swelling (12%). No inhibitor development, thrombotic events or allergic reactions related to this product were observed in this study.

These results are preliminary, top-line data and are subject to additional analyses. Complete results from this study will be submitted for presentation at upcoming medical congresses and submitted for publication in a peer-reviewed journal.

This study was a phase 3, open-label, non-randomized two-period study consisting of six months of on-demand therapy only, followed by 12 months of routine prophylaxis with BeneFIX 100 IU/kg once-weekly. Participants included in this study were males with a mean age of 31.3 years (N=25) and moderately severe to severe hemophilia B (FIX:C =2%). Of the 25 participants enrolled in the study, all received at least one dose of study drug, and no participants discontinued treatment early. The mean duration of treatment was 550 days.


BeneFIX is a recombinant coagulation factor IX product indicated for the control, prevention and perioperative management of bleeding episodes in adult and pediatric patients with hemophilia B. BeneFIX received FDA approval in the US on February 11, 1997, and was approved in the European Union later that year. It has been studied in clinical trials in both previously treated and untreated patients, and established in both on-demand and preventive care, additionally shown to help control bleeds in major and minor surgeries. BeneFIX is not approved for prophylaxis use in the United States.

BeneFIX is an injectable medicine that is used to help control and prevent bleeding in people with hemophilia B. Hemophilia B is also called congenital factor IX deficiency or Christmas disease.

BeneFIX is NOT used to treat hemophilia A.