An Australian case series of six bleeds from four patients with acquired haemophilia A has provided further evidence to support the efficacy of recombinant porcine factor VIII (rpFVIII, Obizur) to treat bleeding in the condition.
Dr Sally Campbell of the Australian Centre for Blood Diseases, Monash University published the reports in the Internal Medicine Journal, showing that rpFVIII was effective in all patients including those who were refractory to initial treatment with a bypassing agent.
Patients in the study, all elderly with extensive bleeding, were treated with the rpFVIII through a compassionate access scheme.
The authors found rpFVIII was efficacious in 100% of bleeds by 24 hours with no adverse events.
Three of the four patients achieved complete remission defined as FVIII level >50%, inhibitor <0.5BU and prednisolone tapered to less than 15mg daily and/or other immunosuppressive therapy discontinued. The fourth patient died following an arterial ischaemic event associated with pre-existing comorbidities.
The findings support a call for public funding of the product through the National Blood Authority.
Co-investigator Dr Campbell told the limbic that Obizur should be in the “toolkit” for acquired haemophilia.
“In terms of the drug itself it is easy to store and has a very long shelf life. It is something you could keep for these cases and would arguably be cheaper than recombinant VIIa which is very expensive.”
She added that factor VIIa had a short half life of less than two hours so had to be given very frequently and was not 100% effective.
“As soon as you stop it the bleeding comes back,” she said.
According to Dr Campbell, the biggest problem with acquired haemophilia is the delay in diagnosis.
“…they are often elderly which means they are often on aspirin or warfarin or another anticoagulant for their other conditions so the bleed is attributed to other causes. By the time you get to the point of diagnosing haemophilia, it’s a couple of days down the track.”
“The key is the spontaneous and quite aggressive onset of mucocutaneous bleeding. And in coagulation studies, a prolonged APTT won’t correct on mixing whereas if they are on warfarin it will.”
She said a FVIII and an inhibitor study were also required to confirm a diagnosis.
“In most people it is a once-off thing after switching off the inhibitors using immunosuppression for example, rituximab and prednisolone.”