Continuous Infusion of Factor VIII and von Willebrand Factor in Surgery: Trials with pdFVIII LFB or pdVWF LFB in Patients with Bleeding Disorders

INTRODUCTION

A plasma-derived factor VIII product (pdFVIII, Factane 100 or 200 IU/mL) and a plasma-derived von Willebrand factor product (pdVWF, Wilfactin 100 IU/mL) are approved for replacement therapy by intravenous bolus injections in haemophilia A (HA) and von Willebrand disease (VWD), respectively. However, in situations requiring intensive treatment, continuous infusion (CI) may be desirable to better control target plasma factor levels.

AIM

To evaluate the perioperative haemostatic efficacy and safety of these concentrates administered by CI.

METHODS

Three phase III trials were conducted. Adults with HA (FVIII:C <1%) (Studies 1 and 2) or VWD (VWF:RCo <20%) (Study 3) received a preoperative bolus followed by CI of undiluted concentrate for at least 6 days. Bolus doses and CI rates were based on individual recovery and clearance, respectively. Initial infusion rate had to be higher for 48 hours for HA and 24 hours for VWD patients to anticipate potential fluctuations of factor concentrations during major surgery. Target levels of FVIII:C in HA and VWF:RCo in VWD were 80 and 70 IU/dL, respectively. Efficacy was assessed using a global haemostatic efficacy score.

RESULTS

Studies 1, 2, and 3 included 12, 4 and 6 patients, respectively. Efficacy outcomes were excellent/good in all 22 major surgeries including 18 orthopaedic procedures. Most daily measured FVIII and VWF levels (92%) were on target. No safety concerns, thrombotic events or inhibitors were identified.

CONCLUSION

pdFVIII and pdVWF administered by CI represent an effective and safe alternative to bolus injections in patients with severe HA or VWD undergoing surgery.

Stability of Turoctocog Alfa, a Recombinant Factor VIII Product, during Continuous Infusion In Vitro

Objective  Turoctocog alfa is a recombinant factor VIII (rFVIII) for the prevention and treatment of bleeding in patients with hemophilia A, including those undergoing surgery and invasive medical procedures. This in vitro study evaluated the physical and chemical stability of turoctocog alfa during continuous infusion (CI) over 24 hours at 30°C.

Materials and Methods  The study was performed at 30°C ( ± 2°C). A CI system with pump speed set at either 0.6 or 1.5 mL/h was used to evaluate the stability of three turoctocog alfa strengths (500, 1,000, and 3,000 IU), equating to doses of 1.1 to 16.1 IU/h per kilogram of body weight. The following parameters were evaluated at selected time points between 0 and 24 hours: appearance of solution, clarity, pH, potency, purity, content, total high molecular weight proteins (HMWPs), and oxidized rFVIII.

Results  The mean potency of turoctocog alfa was maintained within the predefined acceptance criteria during CI for both pump speeds with all three strengths at 6, 12, or 24 hours (500 IU: ≥484 IU/vial; 1,000 IU: ≥1,014 IU/vial; and 3,000 IU: ≥3,029 IU/vial). Furthermore, the appearance of solution, clarity, pH, purity, content of turoctocog alfa, total HMWP, and oxidized forms were also within the predefined limits, and comparable to the reference samples (time = 0 hours) for the pump speeds and product strengths assessed.

Conclusion  Physical and chemical stability of turoctocog alfa was maintained during CI over 24 hours. There was only minor degradation or changes in any of the parameters tested. Potency was within the prespecified acceptance limits throughout 24 hours of infusion. These findings confirm the suitability of turoctocog alfa for CI.

Continuous infusion of coagulation factor concentrates during intensive treatment

In clinical management of bleeds and surgical procedures in patients suffering from bleeding disorders either repetitive bolus injections (BI) or continuous infusion (CI) can be used for coagulation factor replacement. Continuous infusion seems to be an attractive route of administration and may be considered if replacement therapy is required for more than 3 days. The strongest argument favouring continuous infusion is its superiority in providing the patient with a safe and constant level of the deficient coagulation factor by balancing input with clearance. Furthermore, several studies have shown that coagulation factor consumption may be reduced by CI compared to repetitive bolus injections (BI) since unnecessary peaks of factor level are avoided. Concerns have been raised whether continuous infusion of coagulation concentrates is associated with an increased risk of developing inhibitors. However, available data have so far not shown an increased risk for inhibitor development in severe haemophilia patients with more than 50 exposure days of coagulation factor concentrates. Further, previously reported complications when using CI such as phlebitis at the infusion site and pump failure are nowadays very seldom seen when small amounts of heparin are added to the infusion bag, and increased quality of the pumps are available. Over the last decades, numerous reports have confirmed CI to be a safe and effective mode of coagulation factor replacement even in the most challenging surgical procedures, such as total joint arthroplasties.

Comparison of continuous infusion versus bolus injection of factor concentrates for blood management after total knee arthroplasty in patients with hemophilia

Background

Total knee arthroplasty (TKA) has become the treatment of choice for end-stage hemophilic arthropathy of the knee. Theoretically in hemophilia A, perioperative continuous infusion (CI) of factor VIII (FVIII) would provide a more consistent FVIII level than general bolus injections (BI) in TKA. Current study was designed to evaluate the effectiveness of CI of coagulation factor concentrates during the perioperative period compared to BI.

Methods

A total of 42 TKAs were performed in 31 patients with severe hemophilia A. Under the supervision of a multidisciplinary hemophilia team, CI and BI were monitored during application of a standardized regimen. Perioperative clinical parameters including postoperative hemoglobin drop, drained blood volume, transfusion rate, total consumption of FVIII, and perioperative complications were assessed.

Results

The difference in the postoperative hemoglobin drop was significant between two groups with a lower decrease in the CI group (p = 0.002). The drained blood volume for postoperative 24 h was significantly lower in the CI than the BI groups (p = 0.037). Total consumption of factor concentrates for postoperative 5 days was greater in the CI group than in the BI group (p = 0.000). One postoperative hematoma and wound dehiscence occurred in BI group and no other complication developed.

Conclusions

Although good control of hemostasis could be achieved using either method during the perioperative period of TKA, CI seems more tolerable and effective than BI to provide perioperative blood management undergoing TKA in patients with hemophilia.

Trial registration

The study was retrospectively registered in WHO ICTRP under identifier KCT0002404 (date of registration: August 04, 2017).

A close insight to factor VIII inhibitor in the congenital hemophilia A

INTRODUCTION

Hemophilia A (HA) has an X-linked pattern of inheritance and is the most common of the hemorrhagic disorders. HA is caused by a decreased or deficiency of the functional clotting factor VIII (FVIII) and effects 1 in 5000-10,000 male births. The common treatment for hemophilia is replacement therapy by plasma-derived or recombinant FVIII. Approximately 20-30% of people with a severe type of HA develop an inhibitor and this phenomenon is the main challenge in the management of these patients. Genetic factors and environmental determinants contribute to inhibitor development. Here, the roles of various genetic and environmental factors such as the type of FVIII concentrate used, the number of exposure days, and peak treatment time will be discussed in detail. It seems this information is helpful for hematologists.

AREAS COVERED

A literature review was done in January 2016 on PubMed and Scopus using the following keywords:' h(a)emophilia A & factor VIII inhibitor', 'h(a)emophilia A & factor VIII alloantibody', 'h(a)emophilia A & inhibitor'. There was no time limitation; however, there was an English language limitation placed on the articles selected. Expert commentary: Influential genetic and environmental factors in developing inhibitors have been discussed. Most of the risk factors are related to previously untreated patients with hemophili.

Turoctocog alfa: an evidence-based review of its potential in the treatment of hemophilia A

Turoctocog alfa is the first B-domain-truncated third generation recombinant coagulation factor VIII (FVIII) product. Nonclinical in vitro and animal model studies have demonstrated that turoctocog alfa has similar functional potency and hemostatic efficacy as comparator FVIII products. With respect to discrepancies in the level of FVIII concentrate in plasma of current FVIII products on comparing measurement results between one-stage clot and chromogenic assays, there was no difference in the in vitro turoctocog alfa study; however, measured FVIII concentrate in field study was higher with the chromogenic assay (1.08 IU/mL) than with one-stage assay (0.83 IU/mL). Two published clinical studies on previously treated patients (PTPs) and clinical pharmacokinetics have described that the pharmacokinetic parameters are similar, and the safety and efficacy for prevention and treatment for bleeding are also similar to those of standard half-life FVIII products. Three clinical trials are ongoing to assess the long-term safety and efficacy of turoctocog alfa for PTPs and previously untreated patients. Those data will be published in the near future, and it will be possible to use turoctocog alfa for all hemophilia patients. However, studies will be needed to confirm the turoctocog alfa profile, such as the stability of dissolved turoctocog alfa over 24 hours at room temperature and post-marketing clinical research aimed at meeting Europe Medicines Agency post-marketing safety and efficacy requirements in PTPs. It is recommended to wait before using turoctocog alfa for previously untreated patients and major surgery until further data have been collected and published.