Plasma and albumin-free recombinant factor VIII: pharmacokinetics, efficacy and safety in previously treated pediatric patients.
BACKGROUND
The pharmacokinetics of factor VIII replacement therapy in preschool previously treated patients (PTPs) with hemophilia A have not been well characterized.


OBJECTIVE
To assess the pharmacokinetics, efficacy and safety of a plasma-free recombinant FVIII concentrate, ADVATE [Antihemophilic Factor (Recombinant), Plasma/Albumin-Free Method, rAHF-PFM], in children < 6 years of age with severe hemophilia.


METHODS
Fifty-two boys, one girl, mean (+/- SD) age 3.1 +/- 1.5 years and >or= 50 days of prior FVIII exposure, were enrolled in a prospective study of ADVATE rAHF-PFM at 23 centers.


RESULTS
The mean terminal phase half-life (t(1/2)) was 9.88 +/- 1.89 h, and the mean adjusted in vivo recovery (IVR) was 1.90 +/- 0.43 IU dL(-1) (IU kg(-1))(-1). Over the 1-6-year age range, t(1/2) of rAHF-PFM increased by 0.40 h year(-1). IVR increased by 0.095IU dL(-1)(IU kg(-1))(-1) (kg m(-2))(-1) in relation to body mass index (BMI). Patients primarily received prophylaxis. Median (range) annual joint bleeds were 0.0 (0.0-5.8), 0.0 (0.0-6.1) and 14.2 (0.0-34.5) for standard prophylaxis, modified prophylaxis and on-demand treatment, respectively. Bleeds were managed in 90% (319/354) of episodes with one or two rAHF-PFM infusions; response was rated excellent/good in 93.8% of episodes. Over a median 156 exposure days, no FVIII inhibitors were detected and no related severe adverse events or unusual non-serious adverse events were seen.


CONCLUSIONS
Children < 6 years of age appear to have shorter FVIII t(1/2) and lower IVR values than older subjects. However, these parameters increased with age (t(1/2)) and BMI (adjusted IVR), respectively. rAHF-PFM was clinically effective and well tolerated, with no signs of increased immunogenicity in previously treated young children with hemophilia A.
Blanchette
V S
VS
Hospital for Sick Children, University of Toronto, ON, Canada. victor.blanchette@sickkids.ca
Shapiro
A D
AD
Liesner
R J
RJ
Hernández Navarro
F
F
Warrier
I
I
Schroth
P C
PC
Spotts
G
G
Ewenstein
B M
BM
D000906:Antibodies / Q000097:blood; D002675:Child, Preschool; D015331:Cohort Studies; D004340:Drug Contamination / Q000517:prevention & control; D005169:Factor VIII / Q000009:adverse effects / Q000302:isolation & purification / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D005260:Female; D006467:Hemophilia A / Q000097:blood* / Q000188:drug therapy* / Q000276:immunology; D006470:Hemorrhage / Q000188:drug therapy / Q000517:prevention & control; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D011994:Recombinant Proteins / Q000009:adverse effects / Q000302:isolation & purification / Q000493:pharmacokinetics / Q000627:therapeutic use; D012449:Safety; D016896:Treatment Outcome
D000906:Antibodies; D011994:Recombinant Proteins; C078147:F8 protein, human; D005169:Factor VIII