Tailoring care to haemophilia patients' needs: which specialty and when?

Concomitant use of bypassing agents with emicizumab for people with haemophilia A and inhibitors undergoing surgery

INTRODUCTION

Surgery in people with haemophilia and factor VIII inhibitors is typically managed with perioperative administration of haemostatic agents to prevent or control the occurrence of bleeding events. Practical experience of surgery in patients with inhibitors who are receiving treatment with emicizumab is growing; however, the novelty of the situation means that standardised guidelines are lacking with regard to the concomitant administration of haemostatic agents, including dose and laboratory monitoring.

AIM

To review approaches to haemostatic management during major and minor invasive procedures in patients with haemophilia A and inhibitors, and to provide recommendations for controlling bleeding events.

METHODS

A search was conducted, limited to the past 4 years (January 2016-April 2020), pertaining to published evidence of surgery for patients receiving emicizumab. Publications identified from the search were manually reviewed to determine studies and case reports relevant for inclusion.

RESULTS

Identified literature and practical experience of the authors were used to build a consensus of practical recommendations for the concomitant administration of haemostatic agents during the perioperative period for elective surgery in patients with inhibitors who are receiving emicizumab.

CONCLUSIONS

The current evidence base indicates that surgery can be successfully performed in patients with inhibitors who are receiving emicizumab and that bypassing agents can be used concomitantly. Data from prospective studies are required to further support recommendations for haemostatic management of surgery in patients receiving emicizumab.

Efficacy of rFVIIIFc versus Emicizumab for the Treatment of Patients with Hemophilia A without Inhibitors: Matching-Adjusted Indirect Comparison of A-LONG and HAVEN Trials

Purpose

Primary prophylaxis, using factor VIII replacement, is the recognized standard of care for severe hemophilia A. Recombinant factor VIII-Fc fusion protein (rFVIIIFc) and emicizumab, a humanized, bispecific antibody, are approved for routine prophylaxis of bleeding episodes in severe hemophilia A. These products have different mechanisms of action, methods of administration and treatment schedules. In the absence of head-to-head trials, indirect treatment comparisons can provide informative evidence on the relative efficacy of the two treatments. The aim of the study was to compare the approved dosing regimens for each product, rFVIIIFc individualized prophylaxis and emicizumab administered once every week (Q1W), every 2 weeks (Q2W) or every 4 weeks (Q4W), based on clinical trial evidence.

Patients and Methods

The comparison was conducted using matching-adjusted indirect comparison since clinical evidence did not form a connected network. Individual patient data for rFVIIIFc (A-LONG) were compared with data for emicizumab (HAVEN trial program) for mean annualized bleeding rate (ABR) and proportion of patients with zero bleeds. Safety data reported across the analyzed treatment arms were tabularized but not formally compared.

Results

After matching, no significant differences were observed between mean ABR for rFVIIIFc and emicizumab administered Q1W, Q2W or Q4W. The proportion of patients with zero bleeds was significantly higher with rFVIIIFc compared with emicizumab administered Q4W (51.2% versus 29.3%, respectively; odds ratio 2.53; 95% confidence interval 1.09–5.89); no significant differences noted when rFVIIIFc was compared with emicizumab administered Q1W or Q2W. The mean number of adverse events expressed per participant was 1.9 for individualized prophylaxis with rFVIIIFc and 3.7–4.0, 4.1 and 3.6 for emicizumab administered Q1W, Q2W or Q4W, respectively.

Conclusion

This indirect treatment comparison suggests that rFVIIIFc individualized prophylaxis is more efficacious than emicizumab Q4W, and at least as effective as more frequent emicizumab regimens, for the management of hemophilia A.

Pharmacokinetics in routine haemophilia clinical practice: rationale and modalities-a practical review

Prophylactic therapy with exogenous clotting factor concentrates in haemophilia A and B aims to achieve levels of circulating FVIII or FIX that are adequate for the prevention or reduction of spontaneous joint bleeding. Historically, a minimum trough level of at least 1% of the normal levels of circulating clotting factor has been targeted using standardised protocols. However, clearance of clotting factor varies between products and patients, and other pharmacokinetic (PK) parameters such as the frequency and magnitude of peaks may be important for ensuring optimal coverage. Thus, it is increasingly recognised that an individualised, PK-based approach to prophylaxis is necessary to achieve optimal protection.

This review focuses on the clinical implications of using PK-guided, individualised prophylaxis in haemophilia to improve patient outcomes and considers practical methods of establishing patients’ PK parameters. The most useful PK parameters will depend on the aim of the specific treatment (e.g. preventing activity-related and traumatic bleeds or addressing subclinical bleeding). In clinical practice, lengthy and frequent post-infusion sampling for PK analysis is costly and a significant burden for patients. However, a Bayesian analysis allows for the estimation of different PK parameters (e.g. half-life, factor concentrations over time, etc.) with only a minimum number of samples (e.g. 4, 24 and 48 h for haemophilia A), by using the patient’s data to adjust a relevant population PK value towards the actual value. Numerous tools are available to aid in the practical use of Bayesian PK-guided dosing in the clinic, including the Web-based Application for the Population Pharmacokinetic Service hosted by McMaster University, Canada. The PK data can be used to determine the appropriate prophylaxis regimen for the individual patient, which can be monitored by assessment of the trough level at each clinic visit.

Collection of PK data and subsequent PK-guided dosing should become standard practice when determining treatment strategies for people with haemophilia.

Clinical practice of personalized prophylaxis in hemophilia: Illustrations of experiences and benefits from two continents

These cases of people with hemophilia (PWH) illustrate the importance of understanding the patient's expectations and desires and adapting treatment to meet these needs, in addition to traditional clinical targets. Population PK modeling and FVIII products with improved PK profiles provide the opportunity to individualize care and improve long-term outcomes.

Patient preferences in the treatment of hemophilia A: impact of storage conditions on product choice

OBJECTIVES

To gain insights into the usage of factor VIII (FVIII) products by patients diagnosed with moderate/severe hemophilia A, and to assess the impact and perceived importance of product storage.

METHODS

In this study, 200 patients diagnosed with moderate or severe hemophilia A across seven countries participated. Data were collected via a 30-minute, face-to-face interview in six countries and via a web-based survey in the seventh country. The questionnaire evaluated the effect of six features associated with FVIII products on the choice of the product; the structure and flow of data collection was designed to eliminate potential bias.

RESULTS

Two-thirds of the respondents were using recombinant FVIII products. Only 17% were generally dissatisfied with current FVIII products, whereas >40% of the respondents were dissatisfied with frequency of administration and storage issues when traveling. The majority noted restrictions in their daily activities, particularly travel and sports. Most of them (85%), stored their product in the refrigerator and of these, 88% believed that it should always be stored there. These patients were also less satisfied with the product overall, more concerned about storage temperature, more restricted in daily activities, and spent more time on preparation and injection compared with patients who stored their product at room temperature. Conjoint analysis revealed that origin of FVIII (plasma-derived vs recombinant) was the strongest driver of product choice among all respondents, followed by storage flexibility (temperature), reconstitution device, and administration frequency. In this study, we did not investigate the efficacy and safety of the product.

CONCLUSION

Not refrigerating FVIII products was associated with greater patient satisfaction and less restriction on daily activities. If efficacy and safety are unaffected, then storing FVIII at room temperature might have a positive impact on product choice. Few patients were aware that FVIII can be stored without refrigeration, suggesting that health care professionals who treat hemophilia should communicate this aspect to the patient (depending on the labeled option); this approach might offer patients greater flexibility when traveling and require less time for reconstitution.

Congenital Factor Deficiencies in Children: A Report of a Single-Center Experience

Congenital factor deficiencies (CFDs) refer to inherited deficiency of coagulation factors in the blood. A total of 481 patients with CFDs, who were diagnosed and followed at our Pediatric Hematology and Oncology Clinic between 1990 and 2015, were retrospectively evaluated. Of the 481 cases, 134 (27.8%) were hemophilia A, 38 (7.9%) were hemophilia B, 57 (11.8%) were von Willebrand disease (vWD), and 252 (52.3%) were rare bleeding disorders (RBDs). The median age of the patients at the time of diagnosis and at the time of the study was 4.1 years (range: 2 months to 20.4 years) and 13.4 years (range: 7 months to 31.3 years), respectively. The median duration of the follow-up time was 6.8 years (range: 2.5 months to 24.8 years). One hundred nineteen (47.2%) of 252 patients with RBDs were asymptomatic, 49 (41.1%) of whom diagnosed by family histories, 65 (54.6%) through preoperative laboratory studies, and 5 (4.2%) after prolonged bleeding during surgeries. Consanguinity rate for the RBDs was 47.2%. Prophylactic treatment was initiated in 80 patients, 58 of whom were hemophilia A, 7 were hemophilia B, 13 were RBDs, and 2 were vWD. Significant advances have been achieved during the past 2 decades in the treatment of patients with CFDs, particularly in patients with hemophilias. The rarity and clinical heterogeneity of RBDs lead to significant diagnostic challenges and improper management. In this regard, multinational collaborative efforts are needed with the hope that can improve the management of patients with RBDs.