Results of the WIRK prospective, non-interventional observational study of recombinant activated factor VII (rFVIIa) in patients with congenital haemophilia with inhibitors and other bleeding disorders

Glanzmann Thrombasthenia: Perspectives from Clinical Practice on Accurate Diagnosis and Optimal Treatment Strategies

Glanzmann thrombasthenia (GT) is a rare autosomal recessive disorder of fibrinogen-mediated platelet aggregation due to a quantitative or qualitative deficit of the α_IIbβ₃ integrin at the platelet surface membrane resulting from mutation(s) in ITGA2B and/or ITGB3. Patients tend to present in early childhood with easy bruising and mucocutaneous bleeding. The diagnostic process requires consideration of more common disorders of haemostasis and coagulation prior to confirming the disorder with platelet light transmission aggregation, flow cytometry of CD41 and CD61 expression, and/or exon sequencing of ITGA2B and ITGB3. Antifibrinolytic therapy, recombinant activated factor VII, and platelet transfusions are the mainstay of therapy, although the latter may trigger formation of anti-platelet antibodies in GT patients and inadvertent platelet-refractory disease. The management of these patients therefore remains complex, particularly in the context of trauma, labour and delivery, and perioperative care. Bone marrow transplantation remains the sole curative option, although the venue of gene therapy is being increasingly explored as a future alternative for definitive treatment of GT.

Efficacy and Safety of Recombinant Activated Factor VII Off-label Use in a Pediatric Hematology/Oncology Cohort

BACKGROUND

Recombinant activated factor VII (rFVIIa) has been used off-label to treat or prevent severe bleeding in patients for whom conventional treatments are unsuccessful. However, studies in children remain limited.

PROCEDURE

To examine the efficacy and safety of rFVIIa, we performed a retrospective analysis of rFVIIa off-label use in a pediatric hematology/oncology cohort at a single center from 2006 to 2014.

RESULTS

Of 58 patients identified, 46 (79.3%) received rFVIIa to treat bleeding and 12 (20.7%) to prevent bleeding. Thirty-three (71.7%) patients had life-threatening bleeding. In the treatment group, 63.0% patients were responders (ie, bleeding decreased or stopped) and 37.0% were nonresponders (ie, bleeding did not change). Blood products usage was similar between responders and nonresponders. After rFVIIa administration, prothrombin time, partial thromboplastin time and lactate were significantly lower, but fibrinogen was significantly higher in responders than nonresponders. Venous thromboembolism developed in 5.2% (3/58) patients, but its relation to rFVIIa remains unclear. Responders had significantly lower mortality than nonresponders (17.2% vs. 82.4%, P<0.0001).

CONCLUSIONS

rFVIIa controlled most bleeding events in this cohort, despite predominance of life-threatening bleeding, suggesting good efficacy. Venous thromboembolism rate was low. Further studies are warranted to identify predictors of favorable response to rFVIIa in similar patients.

The future of bypassing agents for hemophilia with inhibitors in the era of novel agents

Bypassing agents are presently the standard of care for the treatment of bleeding episodes in patients with hemophilia and high-titer inhibitors and are also used for bleed prevention. Only two bypassing agents are available to patients, and these products trace their lineage to the 1970s (activated prothrombin complex concentrates) and the 1980s (recombinant factor VIIa). Given the limited repertoire of available products, clinicians have relied on experience, empirical observation, registry data and individualized care to improve clinical outcomes on a case-by-case basis. Research over the past two decades has culminated in a greatly improved understanding of human coagulation; resulting from this, new products have been developed that offer treatment options and mechanisms of actions that differ from current bypassing agents. The most advanced in clinical development is emicizumab, a bispecific antibody that mimics the function of FVIIIa in the intrinsic Xase complex and is indicated for once-weekly or every-other-week prophylactic dosing in inhibitor patients. Other non-traditional products in clinical development include fitusiran and antibodies directed against tissue factor pathway inhibitor. As non-factor-based therapies become more widely utilized over time, the use of bypassing agents may be expected to decrease; however, bypassing agents will remain essential for the foreseeable future. As such, clinical development of bypassing agents continues, with some products (e.g. eptacog beta) under regulatory review. In this review we examine the optimal use of bypassing agents and their mechanism of action. We also discuss newer products and how these might theoretically be administered in conjunction with traditional bypassing agents.

Cost-Effectiveness of rFVIIa versus pd-aPCC in the Management of Mild to Moderate Bleeds in Pediatric Patients with Hemophilia A with Inhibitors in Mexico

OBJECTIVE

To compare the costs and clinical consequences of treating mild-to-moderate joint bleeds with recombinant activated factor VII (rFVIIa) versus plasma-derived activated prothrombin complex concentrate (pd-aPCC) in pediatric patients with hemophilia A with inhibitors in Mexico.

METHODS

A cost-effectiveness model was developed using TreeAge Pro v14.2.2 software (licensed in the USA) and adapted from a previously published model, with adjustments to reflect local clinical practice. Expert opinion was sought regarding patients' clinical management and resource utilization in Mexico to ensure that the current model was appropriate and relevant. The model compared rFVIIa and pd-aPCC for the treatment of mild-to-moderate joint bleeds in children <14 years old (assumed average weight: 30 kg). The analysis outcome was incremental cost per resolved mild-to-moderate joint bleed. One-way sensitivity analysis and probabilistic sensitivity analysis were used to assess specific assumptions and to address any uncertainty in the model.

RESULTS

The cost of treating mild-to-moderate joint bleeds was lower for rFVIIa versus pd-aPCC after 7 days (MX$105,581 vs. MX$132,024), assuming complete bleed resolution. After 48 hours, rFVIIa was associated with an 8% improvement in bleed resolution versus pd-aPCC, resulting in cost savings of MX$16,754. Probabilistic sensitivity analysis indicated that rFVIIa treatment was more cost-effective than pd-aPCC in 67% (at 7 days) and 72% (at 48 hours) of Monte Carlo simulations.

CONCLUSION

Accounting for model uncertainty, rFVIIa provided cost savings over pd-aPCC for the Mexican public health care payer in the management of mild-to-moderate joint bleeds in pediatric hemophilia A with inhibitors.

Methodologies for data collection in congenital haemophilia with inhibitors (CHwI): critical assessment of the literature and lessons learned from recombinant factor VIIa

AIMS

To systematically review the effectiveness of on-demand treatment with recombinant coagulation factor VIIa (rFVIIa) in congenital haemophilia with inhibitors and, if feasible, perform a meta-analysis of the data.

MATERIALS AND METHODS

Publications from Embase^® , MEDLINE^® , MEDLINE^® In-Process and the Cochrane Central Register of Controlled Trials were searched. Selected publications were reviewed for inclusion by two independent expert reviewers. Discrepancies were reconciled by a third independent reviewer. Data from selected studies were extracted using a predefined grid to ensure uniform and comparable results were captured.

RESULTS

A systematic search (cut-off date of 2 May 2016) identified 20 studies (13 observational; seven randomized controlled trials). All studies were of sufficient quality to include in this analysis and comprised 1221 participants, with 5981 bleeds in 746 individuals treated with rFVIIa. Haemostatic overall effectiveness of the individual studies identified ranged from 68% to 100% at ≤12 hours, 86% to 96% at 13-24 hours and 76% to 99% at 24-48 hours with rFVIIa <100 μg/kg, with similar rates reported for the ≥250 μg/kg dose. However, heterogeneity between the studies precluded pooling of results.

CONCLUSIONS

Data from the individual studies confirmed that rFVIIa is an effective therapy for the on-demand treatment of bleeds in congenital haemophilia with inhibitors. However, the high levels of heterogeneity between studies precluded pooling of results for a valid, reliable or precise summary measure. There remains a need to implement standardized clinical definitions and measurements for the effectiveness and safety of haemophilia therapies in future clinical trials.

Safety and efficacy of recombinant activated coagulation factor VII in congenital hemophilia with inhibitors in the home treatment setting: A review of clinical studies and registries

Self-administration of factor and bypassing agents by persons with hemophilia in the home setting is recommended to facilitate earlier intervention after bleeding episodes. The objective of this review was to summarize recombinant activated coagulation factor VII (rFVIIa) safety and efficacy data from clinical trials and patient registries documenting use in the home treatment setting in people with congenital hemophilia with inhibitors (CHwI). A total of 16 studies and registries were identified for inclusion; 14 evaluated on-demand treatment of acute bleeding episodes (865 patients, 9024 bleeding episodes) and 2 evaluated use for secondary prophylaxis (108 patients, 42,861 prophylaxis days). In the on-demand studies, efficacy was consistently high (81%-96%), and thrombotic events were uncommon (n = 3). In the secondary prophylaxis studies, rFVIIa was associated with a 45% to 59% reduction in bleeding episodes and no thrombotic events. These data support the clinical practice of administering rFVIIa in patients in the home treatment setting after initiation under a physician's care.

Combination of FVIII and low-dose rFVIIa improves haemostasis in acquired haemophilia A patients: a collaborative controlled study

INTRODUCTION

Acquired haemophilia A (AHA) is an autoimmune disease that potentially leads to severe bleeding and has a high rate of mortality. This collaborative study aimed to assess the efficacy of the co-administration of FVIII and low-dose rFVIIa in patients with AHA.

MATERIALS AND METHODS

This study retrospectively compared the combined FVIII/low-dose rFVIIa therapy (initial dose range of 25-55μg/Kg) with the combined FVIII/PCC therapy and low-dose rFVIIa monotherapy. Adverse drug reactions and recurrent bleeding episodes were also monitored. Crude comparisons and the exact conditional logistic regression were performed to compare the outcomes between three treatment groups.

RESULTS

First bleeding episodes of 56 consecutive patients from 5 centres were analyzed, and 37 bleeding episodes (66.1%) were determined to be severe. Specifically, the rate of bleeding control was significantly higher with the FVIII/low-dose rFVIIa therapy compared to that of the low-dose rFVIIa alone therapy or the FVIII/PCC therapy (58.3% vs. 41.7% vs. 95.0%, respectively). Analyzing of total 236 bleeding episodes showed a clear positive association between the early initiation of haemostatic treatment and efficacy. No therapy-related adverse events in which thrombosis predominated were reported.

CONCLUSIONS

The combination of FVIII and low-dose rFVIIa offers an ideal haemostatic cover and may be promoted as a feasible and safe therapy protocol for patients with AHA.