Rituximab as first-line treatment for the management of adult patients with non-severe hemophilia A and inhibitors

Immune complications and their management in inherited and acquired bleeding disorders

Disorders of coagulation, resulting in serious risks for bleeding, may be caused by autoantibody formation or by mutations in genes encoding coagulation factors. In the latter case, antidrug antibodies (ADAs) may form against the clotting factor protein drugs used in replacement therapy, as is well documented in the treatment of the X-linked disease hemophilia. Such neutralizing antibodies against factors VIII or IX substantially complicate treatment. Autoantibody formation against factor VIII leads to acquired hemophilia. Although rare, antibody formation may occur in the treatment of other clotting factor deficiencies (eg, against von Willebrand factor [VWF]). The main strategies that have emerged to address these immune responses include (1) clinical immune tolerance induction (ITI) protocols; (2) immune suppression therapies (ISTs); and (3) the development of drugs that can improve hemostasis while bypassing the antibodies against coagulation factors altogether (some of these nonfactor therapies/NFTs are antibody-based, but they are distinct from traditional immunotherapy as they do not target the immune system). Choice of immune or alternative therapy and criteria for selection of a specific regimen for inherited and autoimmune bleeding disorders are explained. ITI serves as an important proof of principle that antigen-specific immune tolerance can be achieved in humans through repeated antigen administration, even in the absence of immune suppression. Finally, novel immunotherapy approaches that are still in the preclinical phase, such as cellular (for instance, regulatory T cell [Treg]) immunotherapies, gene therapy, and oral antigen administration, are discussed.

Nonsevere hemophilia A: often overlooked, but not forgotten

PURPOSE OF REVIEW

Nonsevere hemophilia A (NSHA) patients have received relatively little clinical and research attention as compared with their severe counterparts. There is increasing recognition that despite their milder bleeding phenotype, the management of NSHA can be a challenge, with most management decisions largely inferred from severe hemophilia A data. This review focuses on some of the more recent developments in the field of NSHA.

RECENT FINDINGS

Epidemiologic studies suggest that NSHA remain under-recognized and under-diagnosed globally. As the NSHA population ages, they are susceptible to age-related comorbidities. Large cohort studies of NSHA report that the most common primary cause of death is malignancy. NSHA patients have a lifetime risk of inhibitor development with increasing exposure to factor VIII concentrate. Even so, not all patients with inhibitors will require eradication treatment, irrespective of bleeding phenotype at time of inhibitor development.

SUMMARY

As there are currently no evidence-based strategies for inhibitor eradication in NSHA patients, preventive strategies are critical to mitigate inhibitor risk in NSHA. There is a need for active surveillance of NSHA patients by hemophilia treatment centers to address hemophilia-related issues and other age-related comorbidities, in collaboration with primary care physicians and other subspecialists.

Perioperative laboratory monitoring in congenital haemophilia patients with inhibitors: a systematic literature review

: Although the use of clotting factor concentrates is the mainstay of haemophilia care, the development of inhibitors complicates disease management. Perioperative management of patients with inhibitors is therefore a challenge. A systematic literature review was performed to identify literature reporting on the perioperative monitoring and management of haemophilia. MEDLINE, Embase and Cochrane databases were searched from database inception to 26 March 2018. Recent congress proceedings were also searched. Titles and abstracts, then full texts, were screened for relevance by two reviewers. Quality of included studies was assessed using the Critical Appraisal Skills Programme checklist. Of the 2033 individual entries identified, 86 articles met the inclusion criteria. The identified studies were screened again to find articles reporting perioperative laboratory monitoring in patients with congenital haemophilia A or B, resulting in 24 articles undergoing data extraction. Routine perioperative assay monitoring practices were the most commonly reported (n = 20/24); thrombin generation assay was the least commonly reported (n = 2/24). Other monitoring practices described were factor VII and factor VIII coagulation activity (n = 8/24, n = 5/24, respectively), and thromboelastography or rotational thromboelastometry assessments (n = 3/24). The impact of monitoring on treatment decisions was, however, rarely reported. In conclusion, many methods of perioperative monitoring of haemophilia patients with inhibitors have been identified in this review, yet there is a lack of reporting in larger scale cohort studies. More detailed reporting on the impact of monitoring outcomes on treatment decisions is also needed to share best practice, particularly as new therapeutic agents emerge.

Inhibitors in haemophilia A and B: Management of bleeds, inhibitor eradication and strategies for difficult-to-treat patients

The standard therapy for patients with haemophilia is prophylactic treatment with replacement factor VIII (FVIII) or factor IX (FIX). Patients who develop inhibitors against FVIII/FIX face an increased risk of bleeding, and the likelihood of early development of progressive arthropathy, alongside higher treatment-related costs. Bypassing agents can be used to prevent and control bleeding, as well as the recently licensed prophylaxis, emicizumab, but their efficacy is less predictable than that of factor replacement therapy. Antibody eradication, by way of immune tolerance induction (ITI), is still the preferred management strategy for treating patients with inhibitors. This approach is successful in most patients, but some are difficult to tolerise and/or are unresponsive to ITI, and they represent the most complicated patients to treat. However, there are limited clinical data and guidelines available to help guide physicians in formulating the next treatment steps in these patients. This review summarises currently available treatment options for patients with inhibitors, focussing on ITI regimens and those ITI strategies that may be used in difficult-to-treat patients. Some alternative, non-ITI approaches for inhibitor management, are also proposed.

[Study on risk factors and follow-up of 26 hemophilia A children with inhibitors]

目的

探讨中国血友病A(HA）患儿凝血因子Ⅷ（FⅧ）抑制物发生的危险因素、治疗及转归以及抑制物对HA患儿出血特征的影响。

方法

回顾性分析2010年1月至2014年12月445例HA患儿的临床资料。采用病例对照研究方法分析抑制物发生的危险因素。

结果

在纳入研究的445例HA患儿中，重型患者82例（18.4%），中间型患者269例（60.5%），轻型患者94例（21.1%）。抑制物阳性26例（5.8%，失访3例），低滴度抑制物9例，高滴度抑制物17例，其中重型、中间型患者各13例。高强度替代治疗是抑制物产生的危险因素[P=0.030，HR值为4.435(95% CI 1.150~17.094）]；抑制物产生后2例患者接受小剂量利妥昔单抗清除抗体治疗，其中1例联合免疫耐受治疗3个月。出血时65.2%（15/23）的患者选择凝血酶原复合物治疗，8.7%（2/23）选择制动、冰敷、抬高患肢等保守治疗措施，26.1%（6/23）选择间断输注小剂量FⅧ治疗。未接受抗体清除治疗的患者中，87.5%（7/8）低滴度抑制物转阴，抑制物中位持续时间为3(1~3）个月，84.6%（11/13）的高滴度抑制物随时间呈下降趋势，在未进行抗体清除治疗的情况下持续12~48个月仍未转阴，7.7%（1/13）的高滴度抑制物2年后转阴。抑制物产生前后患儿关节年出血率、非关节年出血率、自发年出血率、创伤性年出血率差异无统计学意义。

结论

高强度替代治疗是HA患儿抑制物产生的危险因素；抑制物并不能增加HA患儿出血频率。