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Recombinant factor IX recovery and inhibitor safety: a Canadian post-licensure surveillance study
Man-Chiu Poon1, David Lillicrap, Caroline Hensman
1University of Calgary, Alberta, Canada. mcpoon@ucalgary.ca
Insights
Recombinant factor IX (rFIX) showed lower recovery than plasma-derived factor IX (pdFIX) in Canadian patients. Inhibitor development rates were similar between rFIX and pdFIX, with no thrombotic events reported for rFIX.
Area of Science:
- Hematology
- Pharmacovigilance
- Biotechnology
Background:
- Post-licensure surveillance is crucial for assessing the real-world safety and efficacy of therapeutic agents.
- Recombinant factor IX (rFIX) offers an alternative to plasma-derived factor IX (pdFIX) for hemophilia treatment.
- Understanding factor IX recovery and inhibitor development is essential for patient management.
Purpose of the Study:
- To evaluate factor IX recovery and inhibitor development in patients receiving recombinant factor IX (rFIX) as part of Canadian post-licensure surveillance.
- To compare the recovery rates of rFIX with historical plasma-derived factor IX (pdFIX) data.
- To assess the safety profile of rFIX, including adverse events and inhibitor formation.
Main Methods:
- Post-licensure surveillance study involving 126 patients receiving rFIX and comparison with 74 patients who received pdFIX.
- Analysis of factor IX recovery, expressed as FIX activity increase per unit of concentrate infused.
- Monitoring for inhibitor development and other adverse events, including thrombotic episodes.
Main Results:
- Factor IX recovery was significantly lower for rFIX (mean 0.77) compared to pdFIX (mean 1.05).
- Lower recovery was observed in younger patients (< or =15 years) for both rFIX and pdFIX.
- Two of 244 patients developed de novo inhibitors with anaphylaxis during rFIX treatment, similar to pdFIX rates. No thrombotic events were reported for rFIX.
Conclusions:
- rFIX demonstrates a lower factor IX recovery compared to pdFIX, particularly in younger patients.
- The incidence of de novo inhibitors with anaphylaxis associated with rFIX is comparable to that of pdFIX.
- rFIX appears to have a similar safety profile to pdFIX regarding inhibitor development and thrombotic events.
Abstract:
As part of the Canadian post-licensure surveillance on the safety of recombinant factor IX (rFIX. BeneFIX), factor IX recovery and inhibitor development were studied. The recovery following rFIX infusion in 126 patients (mean = 0.77, median 0.72, range 0.36-1.85, 95% CI of mean 0.74-0.81, expressed as FIX activity increase in U/dL per IU FIX concentrate/kg body weight infused) was significantly lower than that following the last plasma-derived factor IX (pdFIX) infusion in 74 patients (mean 1.05, median 1.00, range 0.37-2.29, 95% CI of mean 0.99-0.97). The recovery for rFIX for patients aged < or =15 years (n = 41, mean recovery 0.64) and that for patients aged >15 years (n = 85, mean 0.84) was each significantly lower than that for pdFIX (aged < or =15 years: n = 21, mean recovery 0.91; aged >15 years: n = 53, mean recovery 1.10). For both rFIX and pdFIX concentrates, the recovery was lower in patients < or =15 years of age compared to those > 15 years of age. Similar data and conclusions were obtained on 66 patients with paired recovery data from rFIX and pdFIX. Overall, our data are similar to those obtained in formal clinical trials. Two of 244 patients treated with rFIX for up to 5 years have developed de novo inhibitors associated with anaphylaxis, an incidence that is similar to that reported for pdFIX. No other serious adverse events, including thrombotic episodes, were reported. To the best of our knowledge, this is the first formal report of recovery and inhibitor formation on rFIX in a peer-reviewed manuscript form.