Extended Half-Life (EHL) Coagulation Factors: A New Era in the Management of Haemophilia Patients

Despite effective factor replacement and various treatment schedules, there remain several challenges and unmet needs in the prophylactic treatment of hemophilia limiting its adoption and thereby posing an increased risk of spontaneous bleeding. In this regard, extended half-life (EHL) recombinant factor VIII (rFVIII) and factor IX (rFIX) products promise optimal prophylaxis by decreasing the dose frequency, increasing the compliance, and improving the quality of life without compromising safety and efficacy. EHL products might lead to higher trough levels without increasing infusion frequency, or could facilitate the ability to maintain trough levels while reducing infusion frequency. This paper aims to provide a comprehensive review of the rationale for developing EHL coagulation factors and their utility in the management of hemophilia, with special emphasis on optimal techniques for half-life extension and criteria for defining EHL coagulation factors, as well as indications, efficacy, and safety issues of the currently available EHL-rFVIII and EHL-rFIX products. Potential impacts of these factors on quality of life, health economics, and immune tolerance treatment will also be discussed alongside the challenges in pharmacokinetic-driven prophylaxis and difficulties in monitoring the EHL products with laboratory assays.