Patients with hemophilia B who switched from recombinant factor IX-Fc-fusion protein (rFIXFc) or standard half-life (SHL) recombinant factor IX (rFIX) to nonacog beta pegol (N9-GP) experienced lower annualized rates of bleeding and reduced factor consumption for prophylaxis and for treatment of bleeds during a two-year period, according to a real-world study. Man-Chiu Poon, MD, of the University of Calgary in Canada, and colleagues published their findings in Research and Practice in Thrombosis and Haemostasis. According to Dr. Poon, the study provides intra-patient comparative data for patients transitioning to N9-GP from SHL rFIX or extended half-life (EHL) rFIXFc and could therefore hold potential relevance to current clinical practice.
“Clinicians can make use of the real-world comparative data to make decisions on the use of N9-GP versus SHL rFIX or EHL rFIXFc based on product availability, patient preference, patient ability to afford, and patient bleeding phenotype,” Dr. Poon stated.
The retrospective analysis of data from the Canadian Bleeding Disorders Registry database described outcomes for Canadian male patients with hemophilia B who received prophylactic N9-GP for six months or longer. The study began in April 2018, and data were collected through the end of March 2021. Only patients who had available data for at least six months before switching to N9-GP were included in the study.
A primary endpoint of the study was the efficacy of N9-GP for prophylaxis, which was measured by annualized bleeding rate (ABR), among other outcomes. In addition, the researchers evaluated the annualized consumption for prophylaxis and the total overall annualized consumption.
A total of 97 patients were receiving N9-GP at the two-year readout, but only 42 of these patients met eligibility criteria and were included in the final analysis. Patients were a median age of 42 years (range = 7-72), and the median follow-up on N9-GP prophylaxis was 2.3 years. Most patients had severe disease (62%), followed by moderate (36%) and mild (2%) disease.
Before switching to N9-GP, approximately 62% of patients received rFIXFc and 38% of patients received SHL rFIX. All patients received prior treatment as prophylaxis.
During the follow-up period on N9-GP prophylaxis, investigators observed 232 bleeds in 30 patients. About 29% of patients had no bleeds during this period.
The overall median ABR in patients who switched from rFIXFc to N9-GP prophylaxis was 0.73 bleeds/patient/year versus 1.44 bleeds/patient/year during previous treatment with rFIXFc. Additionally, the overall median ABR was 2.10 bleeds/patient/year for those who switched from SHL rFIX to N9-GP compared with 6.06 bleeds/patient/year before switching.
The median total annualized FIX concentrate consumption was 2,152 IU/kg following the switch from SHL rFIX to N9-GP compared with 3,018 IU/kg before switching. The median total annualized FIX concentration consumption was 1,766 IU/kg after the switch to N9-GP compared to 2,278 IU/kg with rFIXFc in the period before the switch.
The median annualized consumption for prophylaxis after versus before the switch from SHL rFIX to N9-GP was 2,045 (range = 827-4,122) IU/kg versus 2,687 (range = 358-23,362) IU/kg, respectively. The median annualized consumption rates for prophylaxis were 1,716 (range = 709-2,425) IU/kg after switching from rFIXFc to N9-GP versus 1,961 (range = 750-3,842) IU/kg in the period prior to the switch.
Limitations of the study included the retrospective design, small sample size, the inclusion of only male patients, and the self-reported nature of many of the data points.
“We need further formal economic research that takes into account not only product cost but also cost for care of bleeding episodes and bleed-related complications,” Dr. Poon noted.
Any conflicts of interest declared by the authors can be found in the original article.
Matino D, Iorio A, Keepanasseril A, et al. Switching to nonacog beta pegol in hemophilia B: Outcomes from a Canadian real-world, multicenter, retrospective study. Res Pract Thromb Haemost. 2022;6(3):e12661.