A Two Centre Experience Of Use Of a Dual Virally Inactivated FVIII/VWF Product (Wilate®) In Patients With Von Willebrand Disease
Authors: Batty Paul A , Khair Kate , Riat Renu , Chen Yun-Han , Bowles Louise , Hart Daniel P , Liesner Ri , Platton Sean , Burgess Clive , Pasi John 
Published: October 2019

Abstract

Introduction
von Willebrand disease (VWD) causes mild to severe bleeding, typically following trauma or surgical intervention. These episodes require treatment with a von Willebrand factor (VWF) containing concentrate; at present the only available concentrates are plasma derived. UK guidelines recommend using concentrates manufactured to the highest standards to reduce the risk of pathogen transmission.

Methods
Wilate® (Octapharma AG, Switzerland) is a dual virally inactivated FVIII/VWF concentrate available in the UK since 2007. Use of Wilate® between 2007 and 2012, including a period of product switching was evaluated in two large haemophilia centres (adult and paediatric). The primary study end-point was efficacy of concentrate usage for the treatment of bleeding and surgery. Efficacy was graded using 4 point ordinal scales that rated efficacy as; excellent, good, moderate or nil. Secondary end points were the occurrence of adverse events (immune, infective or thrombotic) and evidence of response on laboratory parameters.

Results
Between 01/03/07 and 01/05/12 a total of 4,565,450IU of Wilate® were used with data evaluable for 4,125,800IU (90.4%). Eighty two patients (44 male, 38 female) including 33 children (< 18yrs) and 49 adults (≥18yrs) with type 1 (n=29), type 2 (n=34), type 3 diseases (n=16) and acquired von Willebrand syndrome (AVWS) (n=3) were treated. The median age at first treatment was 22.7 yrs (range 0.01- 82.3). The mean recoveries ± SD, following first dose in adults (n=35) were FVIII:C 2.25 ± 0.65; VWF:Ag 2.4 ± 0.70 and VWF:RCo 1.91 ± 0.53.
Fifty three patients (20 < 18yr, 33 ≥ 18yr) received concentrate for 93 surgical interventions (36 major, 36 minor, 21 dental procedures). This included 22 patients with type 1, 22 type 2, 7 type 3 disease and 2 with AVWS. The median loading dose prior to surgery was 2700IU (range 450-7200) corresponding to 43.1IU/kg (range 11.84-125). Surgical procedures were covered with a median of 1 treatment (range 1-13) over a median of 1 day (range 1 – 12). Thirty surgical episodes required ≥2 doses (27 major, 3 minor) with a median second dose of 1800IU (range 450-4500) corresponding to 36.4IU/kg (range 17.9-78.6). Overall efficacy was rated as excellent in 89.2% (n=83), good in 5.4% (n=5), moderate in 4.3% (n=4) and nil in 1.1% (n=1).
Thirty five patients (13 < 18yr, 22 ≥ 18yr) were treated for 80 non-surgical episodes of bleeding or trauma (37 major, 43 minor). This included 10 patients with type 1, 14 type 2, 10 type 3 disease and 1 with AVWS. The median first dose given was 2475 IU (range 250-7200) corresponding to 45.7 IU/kg (range 11.8- 97.8). Bleeding episodes were treated with a median of 2 treatments (range 1-80) over a median of 2 treatment days (range 1-78). Forty-three episodes required ≥2 doses (36 major, 7 minor) with a median follow-up dose of 2700IU (range 250-8100) corresponding to 39.3IU/kg (range 11.8-95.7). Overall efficacy was rated as being excellent in 87.5% (n=70), good in 10.0% (n=8), moderate in 2.5% (n=2) and nil in 0.0% (n=0).
Nine patients (1 < 18yr, 8 ≥ 18yr) were on home treatment regimens using 2,644,200 IU of Wilate® (64.1% total usage). These patients were treated using either on-demand (n=3), regular prophylaxis (n=5) or targeted prophylaxis (n=1). Two patients on prophylaxis switched to Wilate® within the study period with similar efficacy to the previous six months of treatment. Twelve patients were treated for other indications not covered by these categories. Wilate® was used to cover 3 un-complicated deliveries (1 operative and 2 vaginal deliveries).
There were 8 reported adverse events (8 patients), with 4 requiring medical review although not requiring in-patient treatment. One patient had treatment failure (impaired VWF:Ag recovery) on one treatment episode, and has been successfully re-treated. Five patients were re-challenged with only one having a repeat mild reaction. Five patients switched to an alternative product at the discretion of the patient/physician. No accumulation of FVIII was seen in patients treated for ≥3 days (mean change in FVIII:C trough level (first to last) +31.89iu/dl (-124.4 - +116.6)). No thrombosis, TTI or inhibitory antibodies were reported.

Conclusion
Wilate® was efficacious (excellent or good efficacy in > 94%), safe and well tolerated in this heterogeneous group of 82 patients with VWD. Bleed resolution or prevention was 100% with no accumulation of FVIII seen.

Disclosures:
Batty: Octapharma: Research Funding, Travel and conference registration fees Other. Khair:Octapharma: Honoraria, Research Funding, Travel to conferences and regsitration fees Other. Hart:Octapharma: Consultancy, Honoraria, Research Funding, Travel and conference registration fees Other. Liesner:Octapharma: Consultancy, Honoraria, Research Funding, Travel and conference registration fees Other. Pasi:Octapharma: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, travel and conference fees Other.