Case n.2
A 15 year old boy with severe haemophilia A developed inhibitor after 9
exposure days to B-domain-deleted rFVIII (Refacto®, moroctocog
alpha, Wyeth, Cambridge, MA, USA)[15]. He received ITI with FVIIIs
(Refacto® , Kogenate® (Bayer AG, Leverkusen,
Germany),Factane® , Octanate® ). Last inhibitor titer
was 30.4 UB/Ml. He received BPA (Novoseven® and then FEIBA® )
for haemarthrosis, ABR stay at 6. He started emicizumab at 14 years old.
During the 1st 4 weeks, ETP and Peak were measured
before injection (Table 1). At the end of initiation phase, residual ETP
was 844 nM*min and Peak was 35.6 nM. 4 weeks after stabilisation phase,
ETP and Peak (3 days after injection) were higher than previously (949
nM*min and 49.1 nM). TG stayed below normal, we added
Novoseven® for surgery. We spiked patient PRP collected 3 days
after 1.5 mg/kg emicizumab injection. With 90 µg/kg of
Novoseven® , we observed no effect in vitro on ETP (939nM*min)
and slight effect on Peak (54,5nM) ; with 120 µg/kg, ETP (1069 Nm*min)
and Peak (69nM) were normalized. 90 µg/kg (usual recommended dose) was
chosen for surgery[16]. Central catheter was removed after ten weeks
of emicizumab treatment and 30 minutes after 90 µg/kg of
Novoseven® . Basal TG values on surgery day measured 2 days
after 1.5 mg/kg emicizumab injection (ETP 1012nM*min, Peak 63.12nM) were
higher than TG measured on spiking day. TG measured ex vivo after rVIIa
infusion was higher than TG measured in vitro after rVIIa spiking (Table
2).