Recombinant activated factor VII in approved indications: Update on safety

Rationale for the Potential Use of Recombinant Activated Factor VII in Severe Post-Partum Hemorrhage

Severe post-partum hemorrhage (PPH) is a major cause of maternal mortality worldwide. Recombinant activated factor VII (rFVIIa) has recently been approved by the European Medicines Agency for the treatment of severe PPH if uterotonics fail to achieve hemostasis. Although large randomized controlled trials are lacking, accumulated evidence from smaller studies and international registries supports the efficacy of rFVIIa alongside extended standard treatment to control severe PPH. Because rFVIIa neither substitutes the activity of a missing coagulation factor nor bypasses a coagulation defect in this population, it is not immediately evident how it exerts its beneficial effect. Here, we discuss possible mechanistic explanations for the efficacy of rFVIIa and the published evidence in patients with severe PPH. Recombinant FVIIa may not primarily increase systemic thrombin generation, but may promote local thrombin generation through binding to activated platelets at the site of vascular wall injury. This explanation may also address safety concerns that have been raised over the administration of a procoagulant molecule in a background of increased thromboembolic risk due to both pregnancy-related hemostatic changes and the hemorrhagic state. However, the available safety data for this and other indications are reassuring and the rates of thromboembolic events do not appear to be increased in women with severe PPH treated with rFVIIa. We recommend that the administration of rFVIIa be considered before dilutional coagulopathy develops and used to support the current standard treatment in certain patients with severe PPH.

The safety of activated eptacog beta in the management of bleeding episodes and perioperative haemostasis in adult and paediatric haemophilia patients with inhibitors

Introduction

Haemophilia patients with inhibitors often require a bypassing agent (BPA) for bleeding episode management. Eptacog beta (EB) is a new FDA‐approved recombinant activated human factor VII BPA for the treatment and control of bleeding in haemophilia A or B patients with inhibitors (≥12 years of age). We describe here the EB safety profile from the three prospective Phase 3 clinical trials performed to date.

Aim

To assess EB safety, immunogenicity and thrombotic potential in children and adults who received EB for treatment of bleeding and perioperative care.

Methods

Using a randomized crossover design, 27 subjects in PERSEPT 1 (12‐54 years) and 25 subjects in PERSEPT 2 (1‐11 years) treated bleeding episodes with 75 or 225 μg/kg EB initially followed by 75 μg/kg dosing at predefined intervals as determined by clinical response. Twelve PERSEPT 3 subjects (2‐56 years) received an initial preoperative infusion of 75 μg/kg (minor procedures) or 200 μg/kg EB (major surgeries) with subsequent 75 μg/kg doses administered intraoperatively and post‐operatively as indicated. Descriptive statistics were used for data analyses.

Results

Sixty subjects who received 3388 EB doses in three trials were evaluated. EB was well tolerated, with no allergic, hypersensitivity, anaphylactic or thrombotic events reported and no neutralizing anti‐EB antibodies detected. A death occurred during PERSEPT 3 and was determined to be unlikely related to EB treatment by the data monitoring committee.

Conclusion

Results from all three Phase 3 trials establish an excellent safety profile of EB in haemophilia A or B patients with inhibitors for treatment of bleeding and perioperative use.

The Use of Recombinant Activated Factor VII in Patients with Glanzmann's Thrombasthenia

Platelet transfusion is the standard treatment to control or prevent bleeding in patients with Glanzmann's thrombasthenia (GT), but platelets are often unavailable. Recombinant activated factor VII (rFVIIa) is an effective alternative to platelets in patients with GT with past/present refractoriness to platelet transfusions and antibodies to platelets. However, there is an unmet need for an alternative to platelets in patients without antibodies. This report summarizes evidence of efficacy and safety of rFVIIa in patients with GT without refractoriness or antibodies to platelets from three different sources: the Glanzmann's Thrombasthenia Registry (GTR), published literature (January 01, 1999 to December 01, 2017), and the Novo Nordisk safety surveillance database. In the GTR, 133 patients received rFVIIa for the treatment of 333 bleeding episodes and prevention of bleeding in 157 surgical procedures. Overall efficacy rates were 79 and 88%, respectively, in patients treated for bleeding episodes or for the prevention of bleeding during surgery; effectiveness was generally similar across refractoriness/antibody status categories. Median dose per infusion of rFVIIa was close to that recommended for patients with GT (90 µg/kg). Data from 14 published case reports also demonstrated that rFVIIa is effective with an acceptable safety profile in patients with GT without antibodies to platelets. Analysis of adverse events reported in GTR and in Novo Nordisk safety surveillance database did not raise any new safety concerns. These data supported the label extension of rFVIIa to include cases where platelets are not readily available, which was approved by the European Medicines Agency in December 2018.

Thrombotic events with recombinant activated factor VII (rFVIIa) in approved indications are rare and associated with older age, cardiovascular disease, and concomitant use of activated prothrombin complex concentrates (aPCC)

Purpose

Recombinant activated factor VII (rFVIIa; NovoSeven^® RT; Novo Nordisk A/S, Bagsvaerd, Denmark) is approved in the United States for the treatment of bleeding and perioperative management in congenital hemophilia with inhibitors (CHwI), acquired hemophilia (AH), congenital factor VII (FVII) deficiency, and Glanzmann’s thrombasthenia (GT) with refractoriness to platelets. The aim of the current analysis was to review clinical trials and registries pre- and post-licensure for each indication to establish the estimated rate of thrombosis and then to establish the association of all reported thrombotic events (TEs) with certain risk factors listed for many years in the prescribing information (PI).

Patients and methods

A retrospective safety assessment of both clinical trials and registries used to support licensure and postmarketing surveillance was performed. The rate of thrombosis was calculated in the 4 indicated disorders and an assessment of TE risk factors was conducted through a review of all narratives within those indications in the safety database.

Results

In clinical trials and registries used to support licensure and in postmarketing surveillance, the overall rate of thrombosis was 0.17% of 12,288 bleeding and surgical episodes. The specific risk by indication was 0.11% for CHwI, 0.82% for FVII deficiency, 0.19% for GT, and 1.77% for AH. The most common associated risk factor—“elderly” (29%), defined in the PI as age ≥65 years—was particularly prevalent in patients with AH. TE was also frequently reported with concomitant cardiac or vascular disease (18%) and use of activated prothrombin complex concentrates (18%).

Conclusion

Data show that the rate of TEs within the 4 licensed indications is low, as was originally described in the US PI from 1999 to 2009. It has remained stable over time during postapproval surveillance in multiple US and global registries with active surveillance for safety information across the 4 approved indications.