Longer-acting factor VIII to overcome limitations in haemophilia management: the PEGylated liposomes formulation issue

Abstract

Injected factor VIII (FVIII), the current treatment for haemophilia A, leads to major improvements in the quality of life and life expectancy of individuals with this disorder. However, because injected FVIII has a short half-life in vivo, this strategy has major limitations for highly demanding regimens (e.g. prophylaxis, immune tolerance induction, surgery). Newer formulations of longer-acting FVIII are presently under investigation. The use of low molecular weight polyethylene glycol (PEG)-containing liposomes as carriers for recombinant FVIII (rFVIII) results in the prolongation of haemostatic efficacy. Data from preclinical experiments in mice, early clinical evaluations, and pharmacokinetics and pharmacodynamics results indicate that an rFVIII pegylated liposomal formulation may provide potential clinical benefit to patients with severe haemophilia A by prolonging the protection from bleeding. In light of this potential clinical benefit, a multicentre, randomized, active-controlled, non-inferiority phase II trial with two parallel treatment arms and equal randomization after stratification for the presence or absence of target joints in patients and for ages >/=18 years vs. <18 years is currently being conducted. The study will test the hypothesis that rFVIII-Lip once-weekly prophylaxis is not inferior to rFVIII-water for injection thrice-weekly prophylaxis. A total of 250 patients will be enrolled with severe haemophilia A (<1% FVIII) on on-demand or secondary prophylaxis treatment and with documented bleeds or injections during the 6 months before study entry. Sixty-four centres in 14 different countries are involved in the study; recruitment is underway. In Italy, six centres have already included 15 patients (no screening failure). Eight of these patients have completed the run-in phase and have begun the home treatment. No unexpected serious adverse events have been reported thus far. Data emerging from this phase II study will help collect relevant data to overcome current limitations in haemophilia management by employing treatment with longer-acting rFVIII.