A retrospective patient chart review of real-world clinical outcomes and prophylactic factor VIII consumption in Italian patients with haemophilia A switching to extended dosing intervals with rVIII SingleChain

Objective The introduction of long-acting recombinant factor VIII (rFVIII) therapies, with improved pharmacokinetic properties compared with standard-acting FVIII therapies, has reduced treatment burden and improved clinical outcomes for patients with haemophilia A. Clinical trials have shown that rVIII-SingleChain, a long-acting rFVIII, can be used effectively for the prophylactic treatment of haemophilia A. This study aimed to determine real-world dosing intervals, factor utilisation and bleed rates in a cohort of Italian patients with haemophilia A who switched to rVIII-SingleChain from a previous FVIII product.

Material and Methods De-identified patient chart information was provided for 60 patients currently treated with rVIII-SingleChain. Data collected included age, sex, weight, current and prior treatment regimen (prophylaxis/episodic, infusion frequency, dosing), and number of reported bleeds. Prophylactic factor consumption for rVIII-SingleChain and previous product were calculated using the dosing and infusion frequency on the patient’s most recent prescription. The number of reported bleeds was annualised to calculate mean annual bleed rate (ABR) for rVIII-SingleChain and previous product.

Results In total, 60 patients (49 with severe disease, 11 with moderate or mild disease) treated with rVIII-SingleChain prophylaxis were included in the study with 50.9% dosed ≤2 x weekly. Of these, 88% (n=53) were also treated prophylactically with their prior drug, with 54.7% of patients dosing at least 3 x weekly. For the 53 patients switching from prophylaxis with previous product to prophylaxis with rVIII-SingleChain (Table 1), mean +/- standard deviation ABR decreased from 1.8 +/- 1.7 (median, 1.0) with previous drug to 0.5 +/- 1.2 (median, 0.0) with rVIII-SingleChain. The percentage of patients with zero spontaneous bleeds increased from 45.3% to 90.6% of patients. Weekly mean prophylactic factor consumption (IU/kg) was similar with previous drug or rVIII-SingleChain (94.6 +/- 38.5 and 95.0 +/- 37.1, respectively).

Conclusion This study shows that patients switching to rVIII-SingleChain can be well managed when treated with extended prophylactic dosing intervals, with effective bleed prevention and no increase in factor utilisation as compared with their previous FVIII product.

Tab 1. Dosing frequency, consumption and bleeding rates with rVIII-SingleChain and prior FVIII product for all prophylaxis-to-prophylaxis patients and prophylaxis-to-prophylaxis patients with severe disease only.

Publication History

Article published online:
18 June 2021