Haemophilia B is a rare inherited bleeding disorder caused by a lack of clotting factor IX. Many people with severe haemophilia B receive regular preventive treatment (prophylaxis) with extended half-life factor IX products, such as albutrepenonacog alfa (Idelvion®), which reduce the number of infusions needed and help prevent bleeding episodes. However, every patient processes factor IX differently, so treatment should ideally be tailored to the individual.
To personalise treatment, doctors often use pharmacokinetic (PK) analyses, which estimate how long factor IX remains active in the body. Sophisticated computer-based tools such as WAPPS-Hemo are increasingly used for this purpose, but they are not available in every haemophilia centre. We wanted to determine whether a simpler PK approach could provide similarly useful information in routine clinical practice.
We studied 18 people with severe haemophilia B receiving prophylaxis with albutrepenonacog alfa in four Spanish haemophilia centres. We compared the results obtained with WAPPS-Hemo and with a simple one-compartment PK model. We also used the simpler model to estimate the doses needed to maintain different target factor IX levels with dosing intervals of 10, 14 and 21 days.
We found that the simpler model produced pharmacokinetic values that were closer to those reported in previous clinical trials of albutrepenonacog alfa. Our simulations also showed that extending the time between infusions is possible but requires substantially higher doses to maintain adequate protection against bleeding.
These findings suggest that a simple pharmacokinetic model may be a practical and reliable option for individualising prophylaxis, particularly in centres without access to specialised software. More personalised dosing may help patients and healthcare professionals choose treatment schedules that balance protection from bleeding, treatment burden and efficient use of factor IX concentrates. Ultimately, personalised treatment, based on pharmacokinetics, has the potential to improve quality of life by helping each person with haemophilia B receive the right dose at the right interval according to their individual needs.
