Real-World Data on Bleeding Patterns of Hemophilia A Patients Treated with Emicizumab

Emicizumab: the hemophilia A game-changer

In hemophilia, the unmet needs regarding adherence to prophylaxis and lack of effective long-term prophylaxis regimens, especially in patients with inhibitors, led to the production of emicizumab, the first non-factor medicine for subcutaneous administration in patients with severe and moderate hemophilia A with or without factor VIII inhibitors. This review describes the research steps behind the development of this game-changing medication as well as its success in the prophylaxis of bleeding episodes, as witnessed by the results of pivotal clinical trials but also by real-life use in the frame of a still expanding global market. We also discuss potential and actual adverse events and the nuances related to clinical use, such as laboratory monitoring, development of neutralizing antidrug antibodies, risk of thrombosis/hypercoagulability and role in the management of surgical operations. The potential of emicizumab to prevent bleeding in other congenital and acquired coagulation disorders is also outlined.

Emicizumab-mediated hemostatic function assessed by thrombin generation assay in an in vitro model of factor VIII-depleted thrombophilia plasma

Patients with hemophilia A (PwHA) may have concurrent deficiency of representative anticoagulant proteins, protein (P)C, PS, and antithrombin (AT), which reduces bleeding frequency. However, emicizumab-driven hemostasis in PwHA with such thrombophilic potential remains unclarified. This study investigated the influence of natural anticoagulants on emicizumab-driven coagulation in HA model plasma. Various concentrations of PS and AT were added to PS-deficient plasma and AT-deficient plasma in the presence of anti-FVIII antibody (FVIIIAb; 10BU/mL). PC-deficient plasma was mixed with normal plasma at various concentrations in the presence of FVIIIAb. Emicizumab (50 µg/mL) was added to these thrombophilic HA model plasmas, prior to tissue factor/ellagic acid-triggered thrombin generation assays. Co-presence of emicizumab increased peak thrombin values (PeakTh) dependent on PS, AT, and PC concentrations. Maximum coagulation potentials in the PS-reduced HA model plasmas remained normal in the presence of emicizumab. PeakTh were close to normal in the presence of 50%AT irrespective of emicizumab, but were higher than normal in the presence of 25%AT. Addition of recombinant FVIIa (corresponding to an administered dose of 90 μg/kg) enhanced coagulation potential to normal levels. Our findings provide novel information on hemostatic regulation in emicizumab-treated PwHA with a possible thrombophilic disposition.

Expert opinion paper on the treatment of hemophilia a with emicizumab

INTRODUCTION

Prophylaxis with emicizumab, a bispecific monoclonal antibody that mimics FVIII function, has shown encouraging results in clinical trials in terms of efficacy and safety. However, current experience is limited, and many areas of concern to clinicians have yet to be reviewed.

AREAS COVERED

This paper reviews the experience of hemophilia A patients treated with emicizumab based on the results of clinical trials and real-life studies. The authors place special emphasis on issues such as the management of these patients in situations of hemorrhage and/or surgical interventions, joint health or laboratory monitoring.

EXPERT OPINION

Treatment with emicizumab has been shown to improve joint health and reduce bleeding, of particular interest to patients with inhibitors and high bleeding rates. However, there are still concerns about its administration in neonates and previously untreated patients due to limited reported experience. Laboratory monitoring is not strictly necessary due to the stable pharmacokinetics emicizumab has been shown to exhibit, however, tests that globally assess hemostasis may be useful especially in cases of bleeding or surgery. The authors are also of the opinion that prophylaxis before minor surgery is not necessary and that major surgeries can be safely performed with additional prophylactic coagulation factor.Trial registration ClinicalTrials.gov identifier: NCT04431726..

Longitudinal dynamic changes in factor VIII inhibitor titers in patients with hemophilia A and inhibitors receiving emicizumab prophylaxis

Emicizumab prophylaxis dramatically reduces bleeding events in patients with hemophilia A (PwHA) with or without factor VIII (FVIII) inhibitors. However, long-term dynamic changes in FVIII inhibitor titers during emicizumab prophylaxis remain to be investigated. We conducted a retrospective follow-up study of FVIII inhibitor titers after initiation of emicizumab prophylaxis in 25 PwHA carrying current or historical FVIII inhibitors. Nineteen PwHA had FVIII inhibitors at initiation of emicizumab prophylaxis (age: median 22 [range 4-60] years and inhibitor titer: 30 [1.0-1450] BU/mL). In 17 of the 19 patients, the inhibitor titers markedly decreased to a median of 1.2 (< 0.6-58) BU/mL at a median follow-up of 71 (38-111) months. In two patients, titers were slightly elevated after initiation of emicizumab but decreased in the long term. The remaining six patients had negative inhibitor status (< 0.6 BU/mL) when switched to emicizumab from FVIII prophylaxis. Five patients maintained negative titers. One patient had inhibitor recurrence, with a peak titer of 1.6 BU/mL that decreased to 0.9 BU/mL. In most cases, FVIII inhibitor titers can be expected to decrease spontaneously during emicizumab prophylaxis, but regular follow-up is necessary to manage breakthrough bleeds.

Serious bleeds in pediatric persons with hemophilia A on emicizumab prophylaxis

Background

Clinical trials have shown success in bleed prevention with emicizumab, but real-world data on the effectiveness of emicizumab in preventing serious bleeds in the pediatric population are lacking.

Objectives

To report real-world data on the effectiveness of Emicizumab in pediatric persons with hemophilia A.

Methods

We completed a retrospective chart review of 37 pediatric male patients aged ≤18 years on emicizumab prophylaxis for a median duration of 30.5 months at Children's Medical Center in Dallas, Texas.

Results

We identified 4 pediatric persons with severe hemophilia A with and without inhibitors who experienced a provoked or unprovoked serious bleed requiring hospitalization.

Conclusion

This study highlights that serious bleeds, both provoked and unprovoked, can occur in pediatric persons with severe hemophilia A. These findings are important for clinicians to provide appropriate counseling/education and recommendation of treatment for pediatric persons with severe hemophilia A through shared decision making. Up-titration of emicizumab or factor VIII replacement needs consideration in persons with hemophilia with suboptimal bleeding control or who participate in activities categorized as moderate- to high-risk activities.

Pharmacodynamics Monitoring of Emicizumab in Patients with Hemophilia A

BACKGROUND

 Emicizumab is a bispecific antibody mimicking coagulation factor VIII (FVIII) employed to treat patients with hemophilia A (PwHA) regardless of FVIII inhibitor status. The identification of biological markers reflecting the hemostatic competence of patients under emicizumab therapy would have a great clinical value. Unfortunately, emicizumab over-corrects standard coagulation assays, precluding their use for evaluating the hemostatic correction achieved in vivo. Here, we investigated whether global coagulation assays (GCA) would allow monitoring the biological response to non-factor replacement therapy with emicizumab.

MATERIALS AND METHODS

 Six adults PwHA received a weekly dose of emicizumab of 3 mg/kg during weeks (W) 1 4 and 1.5 mg/kg from W5 onwards. Response to treatment was monitored weekly by emicizumab plasma concentration, thrombin generation (TG), and fibrin clot formation (FCF) and structure. TG and FCF results were compared to patient baseline, FVIII replacement, and healthy donors.

RESULTS

 TG and FCF significantly increased in PwHA after the loading period, reaching a plateau that lasted until the end of monitoring. Similarly, fibrin clot network became denser with thinner fibrin fibers. However, TG contrary to FCF remained at the lower limits of reference values. Remarkably, despite having similar plateau concentrations of emicizumab some patients showed markedly different degrees of TG and FCF improvement.

CONCLUSION

 Our study enriches the knowledge on the use of GCA to monitor non-factor replacement therapy, indicating that TG and FCF could act as direct markers of emicizumab biological activity. GCA allow to capture and visualize the individually variable response to emicizumab, leading a step forward to the personalization of patient treatment.

Immunogenicity of Therapeutic Biological Modalities - Lessons from Hemophilia A Therapies

The introduction and development of biologics such as therapeutic proteins, gene-, and cell-based therapy have revolutionized the scope of treatment for many diseases. However, a significant portion of the patients develop unwanted immune reactions against these novel biological modalities, referred to as immunogenicity, and no longer benefit from the treatments. In the current review, using Hemophilia A (HA) therapy as an example, we will discuss the immunogenicity issue of multiple biological modalities. Currently, the number of therapeutic modalities that are approved or recently explored to treat HA, a hereditary bleeding disorder, is increasing rapidly. These include, but are not limited to, recombinant factor VIII proteins, PEGylated FVIII, FVIII Fc fusion protein, bispecific monoclonal antibodies, gene replacement therapy, gene editing therapy, and cell-based therapy. They offer the patients a broader range of more advanced and effective treatment options, yet immunogenicity remains the most critical complication in the management of this disorder. Recent advances in strategies to manage and mitigate immunogenicity will also be reviewed.

Current status and future prospects of activated recombinant coagulation factor VIIa, NovoSeven®, in the treatment of haemophilia and rare bleeding disorders

rFVIIa, a human recombinant activated coagulation factor VII, has been used worldwide for more than two decades for the treatment of bleeding episodes and prevention of bleeding in patients undergoing surgery/invasive procedures with congenital haemophilia A or B with inhibitors (CHwI A or B), acquired haemophilia (AH), congenital factor VII deficiency and Glanzmann thrombasthenia (GT), refractory to platelet transfusion. The approved dosage, administration and indication of rFVIIa in the US, Europe and Japan differ, depending on the needs of the patient population and regulatory practices. This review presents an overview of the current status and future prospects, including that from a Japanese perspective, of using rFVIIa in the treatment of approved indications. The efficacy and safety of rFVIIa in the approved indications has been demonstrated in several randomised and observational studies and data from registries. The overall incidence of thrombosis across all approved indications in a retrospective safety assessment of clinical trials and registries, prelicensure studies and postmarketing surveillance studies of rFVIIa use was 0.17%. Specifically, the risk of thrombotic events was 0.11% for CHwI, 1.77% for AH, 0.82% for congenital factor VII deficiency and 0.19% for GT. Emerging non-factor therapies such as emicizumab have changed the treatment landscape of haemophilia A, including preventing bleeding in patients with CHwI. However, rFVIIa will continue to play a significant role in the treatment of such patients, particularly during breakthrough bleeding or surgical procedures.

A real-world evidence analysis of the impact of switching from factor VIII to emicizumab prophylaxis in patients with hemophilia A without inhibitors

BACKGROUND

This study retrospectively compared annualized billed bleed rates (ABR_b) in people with hemophilia A (PwHA) without inhibitors who switched from factor VIII (FVIII) prophylaxis to emicizumab.

RESEARCH DESIGN AND METHODS

A real-world comparison study was performed on the effect of switching from FVIII to emicizumab prophylaxis in male, non-inhibitor patients on ABR_b using an all-payer claims database (APCD) dataset from 1 January 2014, to 31 March 2021. The identification period was from 1 November 2017, to 30 September 2020.

RESULTS

One hundred and thirty-one patients were included with a total of 82 and 45 bleeds in the pre- and post-switch periods, respectively. The average follow-up period pre-switch was 978.37 days (SD 555.03), whereas the average follow-up period post-switch was 522.26 days (SD 191.36). No significant differences in mean ABR_b were observed pre-/post-switch (0.25 and 0.20, respectively; P = 0.4456).

CONCLUSIONS

The results of this study demonstrate no significant reduction in ABR_b, suggesting that switching from FVIII to emicizumab may not deliver incremental benefits to PwHA receiving prophylactic care.

Impact of switching prophylaxis treatment from factor VIII to emicizumab in hemophilia A patients without inhibitors

BACKGROUND

Factor VIII (FVIII) replacement and emicizumab are effective at preventing bleeds in patients with hemophilia A (HA). Though benefits of emicizumab among inhibitor patients with HA (PwHA) are well established, more real-world evidence among non-inhibitor patients is needed.

METHODS

Using a United States healthcare claims database, we compared billed annualized bleed rates (ABR_b) and the total cost of care (TCC) before and after switching from FVIII prophylaxis to emicizumab among non-inhibitor male PwHA. Bayesian inferences were used to assess the difference in ABR_b and TCC per patient per year (PPPY) pre versus post prophylaxis switch. We included 101 non-inhibitor male PwHA aged between 3 and 63 years old who switched from FVIII prophylaxis to emicizumab prophylaxis in 2018 or 2019.

RESULTS

The ABR_b increased from 0.52 to 0.62 (p = 0.83) after switch. The posterior probability of the mean ABR_b increasing after the switch was 75.54%. The TCC PPPY increased from $517,143 to $627,005 (p < 0.0001) after switch and the posterior probability of mean costs increasing after the switch was 99.80%.

CONCLUSIONS

Personalization of care through the identification of the most appropriate therapy for each patient can optimize clinical and economic outcomes. Future real-world evidence research could help establish the value of prophylactic options in targeted populations such as the non-inhibitor male PwHA.

To Clot or Not to Clot: Is That the Question?

Hemostasis can be defined as a homeostatic process in which the body attempts to minimize loss of blood by balancing out pro- and anti-procoagulant forces [...].

Applicability of the European Society of Cardiology Guidelines on the management of acute coronary syndromes to older people with haemophilia A - A modified Delphi consensus by the ADVANCE Working Group

INTRODUCTION

As people with haemophilia (PWH) receive better treatment and live longer they are more likely to encounter cardiovascular disease (CVD) and other comorbidities. ESC guidelines for the acute management of patients presenting with acute coronary syndrome (ACS) are based on the non-haemophilia population.

AIM

To review the guidelines and propose relevant adaptations for PWHA without inhibitors who are treated with prophylaxis and present with ACS.

METHODS

As part of the ADVANCE Group, 20 European haemophilia experts used a modified Delphi approach to develop and gain consensus on proposed adaptations of the ESC guidelines for PWHA without inhibitors.

RESULTS

Of the 32 Class I recommendations across both guidelines, adaptions were considered necessary and proposed for 15. The adaptions highlight the need to provide sufficient FVIII trough levels at the time of antithrombotic treatment in people with haemophilia A (HA) without inhibitors. Patients receiving emicizumab prophylaxis and requiring oral anticoagulation therapy or combined single antiplatelet plus oral anticoagulation therapy will require additional FVIII replacement therapy.

CONCLUSION

In the absence of high-quality clinical evidence, the combined expert opinion used to develop these adaptions to the current ESC guidelines may help to guide clinicians in their treatment decisions when a PWHA presents with ACS.

Emicizumab dose up-titration in case of suboptimal bleeding control in people with haemophilia A

INTRODUCTION

Emicizumab promotes effective haemostasis in people with haemophilia A (PwHA). It is indicated for routine prophylaxis of bleeding episodes in PwHA with or without factor (F)VIII inhibitors.

AIM

To investigate the effect of emicizumab dose up-titration in PwHA with suboptimal bleeding control.

METHODS

Data from seven completed or ongoing phase III studies were pooled. Pharmacokinetics, pharmacodynamics and bleeding events were evaluated before and after dose up-titration. Adverse events (AEs) were compared between PwHA with and without dose up-titration.

RESULTS

Of 675 PwHA evaluable for the analysis, 24 (3.6%) had their maintenance dose up-titrated to 3 mg/kg once weekly (QW). Two participants had neutralising antibodies (nAbs) associated with decreased emicizumab exposure, and dose increase did not compensate for the effect of nAbs. In the other 22 participants, mean emicizumab steady-state trough concentrations increased from 44.0 to 86.2 μg/mL after up-titration. The median (interquartile range [IQR]) efficacy period prior to up-titration was 24.6 (24.0-32.0) weeks. The model-based annualised bleed rate for 'treated bleeds' and 'all bleeds' decreased by 70.2% and 72.9%, respectively, after a median (IQR) follow-up of 97.1 (48.4-123.3) weeks in the up-titration period. Incidences of injection-site reactions and serious AEs were higher in PwHA with up-titration; however, this was already observed in these participants before the dose up-titration. Overall, the safety profile appeared similar between PwHA with and without up-titration.

CONCLUSION

The dose up-titration to 3 mg/kg QW was well tolerated. Bleed control improved in most participants whose bleeding tendency was inadequately controlled during clinical trials.

A real-world study comparing pre-post billed annualized bleed rates and total cost of care among non-inhibitor patients with hemophilia A switching from FVIII prophylaxis to emicizumab

OBJECTIVE

Factor VIII (FVIII) replacement and emicizumab have demonstrated efficacy for prevention of bleeds among patients with hemophilia A (PwHA) compared to on-demand (OD) use. Evidence investigating clinical outcomes and healthcare costs of non-inhibitor PwHA switching from prophylaxis with FVIII concentrates to emicizumab has not been well-established within large real-world datasets. This study aimed to investigate billed annualized bleed rates (ABR_b) and total cost of care (TCC) among non-inhibitor PwHA switching from FVIII-prophylaxis to emicizumab-prophylaxis.

METHODS

This retrospective, observational study was conducted using IQVIA PharMetrics Plus, a US administrative claims database. The date of first claim for emicizumab was defined as the index date. OD patients and inhibitor patients were excluded. Bleeds were identified using a list of 535 diagnosis codes. Bayesian models were developed to estimate the probability ABR_b worsens and TCC increases after switching to emicizumab. Wilcoxon rank-sum tests were used to test statistical significance of changes in ABR_b and TCC after switch.

RESULTS

Among the 121 identified patients, the difference in mean ABR_b between FVIII-prophylaxis (0.68 [SD = 1.28]) and emicizumab (0.55 [SD = 1.48]) was insignificant (p = .142). The mean annual TCC significantly increased for patients switching from FVIII-prophylaxis ($518,151 [SD = $289,934]) to emicizumab ($652,679 [SD = $340,126]; p < .0001). The Bayesian models estimated a 21.0% probability of the ABR_b worsening and a 99.9% probability of increasing TCC after switch.

CONCLUSIONS

This study found that in male non-inhibitor PwHA, switching from FVIII prophylaxis to emicizumab incurs substantial cost increase with no significant benefit in ABR_b. This evidence may help guide providers, payers, and patients in shared decision-making conversations around best treatment options.

Emicizumab state-of-the-art update

Introduction

Emicizumab is a bispecific monoclonal antibody developed to address the unmet needs of clotting factor replacement therapy and has become the benchmark for optimal prophylaxis in managing patients with haemophilia A with inhibitors. We describe the emicizumab rollout and pharmacokinetic strategies and their use in paediatric patients.

Methods

The evolving real‐world experience in using emicizumab has confirmed its safety, efficacy and pharmacokinetic profile in paediatric, adolescent and adult patients receiving emicizumab at various prophylactic dosing regimens. The emicizumab current global rollout includes over 100 countries with 29 low to middle‐income countries accessing emicizumab through the World Federation of Haemophilia (WFH) Humanitarian Aid Program. The diversity of emicizumab dosing and pharmacokinetic tools such as the Calibra® and the WAPPS‐Hemo platforms make it possible to achieve prophylaxis goals in line with the WFH Haemophilia treatment guidelines recommendations, with minimal drug wastage. The emerging experience from long term clinical trials and long‐term real‐world follow‐up confirm the safety, efficacy, and pharmacokinetic profile of emicizumab in paediatric haemophilia A patients. A few questions, including inhibitor recurrence, concurrent use of emicizumab with various replacement therapies and inhibitor eradication, are being addressed through multiple ongoing clinical studies.

Conclusion

The current global rollout of emicizumab is remarkable, and versatile dosing regimens and evolving pharmacokinetic tools such as the Calibra® and WAPPS‐Hemo platforms make it a treatment choice available also for pharmacokinetic guided personalised treatment. Data from paediatric studies are consistent with those seen in adolescent and adult Haemophilia A.

Early real-world experience with emicizumab and concomitant factor VIII replacement products in adult males with Hemophilia A without inhibitors

AIMS

To assess real-world use of emicizumab in adult people with hemophilia A (PwHA) without inhibitors including healthcare resource utilization (HCRU) and costs.

MATERIALS AND METHODS

Adult, male PwHA without inhibitors initiating emicizumab (index date) were identified using IBM MarketScan after 4 October 2016. Patients were required to have continuous health insurance coverage for ≥180 days prior to and ≥90 days after index date and have ≥90 days of continuous use of emicizumab. Patients were followed until treatment gap, disenrollment, or end of data. Results were reported overall and among a subgroup with prior factor VIII (FVIII) prophylaxis. Emicizumab use, concomitant FVIII treatment use, HCRU, and costs were assessed separately over baseline, the emicizumab induction period, emicizumab maintenance period, and annualized.

RESULTS

Among the 71 emicizumab patients (FVIII prophylaxis subgroup: 52) included in the study, the mean age was 35 (subgroup: 34) years and mean follow-up was 12 (subgroup: 11.1) months. At baseline, the annualized mean total healthcare cost was $532,948 (subgroup: $645,727). After emicizumab initiation, per-patient-per-month (PPPM) HCRU was higher in the emicizumab induction period compared to the maintenance period with higher monthly FVIII fills/in-office administrations (0.37 vs 0.17), non-FVIII outpatient visits (2.23 vs 1.55), and emergency department visits (0.06 vs 0.03). The FVIII prophylaxis subgroup yielded similar HCRU trends. Hemophilia treatment costs accounted for over 95% of total healthcare costs. The annualized mean cost was $50,491 (subgroup: $61,512) for concomitant FVIII treatment and $777,171 (subgroup: $793,168) for emicizumab and concomitant FVIII treatment for the first year of emicizumab treatment.

CONCLUSION

This study represented experience with emicizumab after the approval for PwHA without inhibitors. The study cohort may not be representative of all PwHA taking emicizumab. The findings highlight the continued burden of treatment and healthcare cost for PwHA without inhibitors despite advances in treatment options.