Novel investigations on the protective role of the FVIII/VWF complex in inhibitor development

Emicizumab and unmet needs of patients with hemophilia a who are managed with replacement therapies

INTRODUCTION

Hemophilia A is managed with coagulation clotting factor VIII (FVIII) therapy that poses significant challenges, such as a high treatment burden, immunogenicity, inconsistent hemostatic cover, poor treatment outcomes, and musculoskeletal progression despite adequate prophylactic treatment. Various non-factor therapies, such as several natural anticoagulant inhibitors and factor FVIII mimetics, have been developed to address these unmet needs. However, the role of emicizumab in addressing these unmet needs remains underexplored.

AREAS COVERED

This review delves into the evolution of hemophilia A replacement clotting therapy from plasma-derived products to recombinant products and, more recently, nonfactor therapies. It underscores the unmet needs of replacement therapy and explores the nonfactor therapies developed to address them. The review then comprehensively summarizes the clinical trial and real-world experience data, demonstrating how emicizumab tackles these unsatisfied demands.

EXPERT OPINION

Replacement clotting factor therapies as the standard of care has exposed several needs that have yet to be addressed. However, data from numerous emicizumab clinical trials and real-world experience offer a promising outlook, suggesting that it may effectively address many unmet needs. As hemophilia treatment goals continue to evolve, the role of currently developed nonfactor therapies in hemophilia management is yet to be fully defined.

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.

Association between interleukin-2 (rs2069762) gene polymorphism and FVIII inhibitor development in Indonesian patients with severe hemophilia A

BACKGROUND Factor VIII (FVIII) inhibitors in hemophilia A (HA) patients render FVIII replacement therapy ineffective. Although its development cause is unclear, it has been classified into therapeutic and genetic-related etiologies. Single nucleotide polymorphisms (SNPs) in several cytokine genes, including interleukin (IL)-2, could increase the risk of FVIII inhibitor development. This study aimed to evaluate the association between IL-2 (rs2069762) gene SNP and FVIII inhibitor development in Indonesian patients with severe HA. METHODS The IL-2 (rs2069762) gene SNP was examined in 119 HA patients. The presence of FVIII inhibitors was quantified using an enzyme-linked immunosorbent assay, with a titer of <0.28 ng/ml considered negative. Patients were divided into two groups: 59 with FVIII inhibitors (positive group) and 60 without inhibitors (negative group). The genotype of the subjects was determined using peripheral blood mononuclear cells and tetra-primer amplification refractory mutation system-polymerase chain reaction. RESULTS There was no association between IL-2 (rs2069762) gene polymorphism and FVIII inhibitor development on genotypes (p = 0.138) and allele frequencies (p = 0.780). CONCLUSIONS IL-2 (rs2069762) gene polymorphism is not a risk factor in the development of FVIII inhibitors in Indonesian patients with severe HA. Thus, further polymorphism studies in other cytokine genes are required to gain a comprehensive understanding of the FVIII inhibitor development.

Plasma-derived FVIII/VWF complex shows higher protection against inhibitors than isolated FVIII after infusion in haemophilic patients: A translational study

Introduction

Presence of von Willebrand factor (VWF) in FVIII concentrates offers protection against neutralizing inhibitors in haemophilia A (HA). Whether this protection is more evident in plasma‐derived (pd) FVIII/VWF or recombinant (r) FVIII concentrates remains controversial.

Aim

We investigated the protection exerted by VWF against FVIII inhibitors in an in vivo mouse model of HA exposed to pdFVIII/VWF or to various rFVIII concentrates.

Methods

Haemophilia A mice received the different FVIII concentrates after administration of vehicle or an inhibitory IgG purified from a commercial pool of HA plasma with inhibitors and FVIII:C recoveries were measured. Furthermore, using a novel clinically oriented ex vivo approach, Bethesda inhibitory activities (BU) of a commercial pool of HA plasma with inhibitors were assessed using normal plasma, or plasma from severe HA patients, without inhibitors, after treatment with the same concentrates.

Results

in vivo studies showed that pdFVIII/VWF offers markedly higher protection against inhibitors when compared with any of the FVIII products without VWF. More importantly, in the ex vivo studies, plasma from patients treated with pdFVIII/VWF showed higher protection against inhibitors (P values ranging .05‐.001) in comparison with that observed in plasma from patients who received FVIII products without VWF, regardless of the type of product evaluated.

Conclusion

Data indicate that FVIII+VWF complexes assembled in the circulation after rFVIII infusion are not equivalent to the naturally formed complex in pdFVIII/VWF. Therefore, rFVIII infused into HA patients with inhibitors would be less protected by VWF than the FVIII in pdFVIII/VWF concentrates.

Clinicopathological parameters influencing inhibitor development in patients with hemophilia A receiving on-demand therapy

BACKGROUND

Development of inhibitors to transfused factor VIII in patients with hemophilia A continues to be a challenge for professionals involved in hemophilia care. The majority of patients in India receive 'on-demand' rather than prophylactic therapy. The present study was done to assess the prevalence of factor VIII inhibitors in patients with hemophilia A (PWHA) receiving 'on-demand' therapy in a North Indian population and to study the clinicopathological parameters influencing the development of inhibitors.

METHODS

The study group comprised of 300 PWHA. Detailed clinical parameters, treatment history, bleeding profile including family history were recorded. Diagnosis of hemophilia A was confirmed by relevant coagulation tests. Inhibitors were screened using mixing based studies followed by quantification by Bethesda assay and Nijmegen modified Bethesda assay. Samples were collected from five cities in North India where a free supply of factor VIII was available and effectively used in three of these cities.

RESULTS

In the 300 PWHA, disease phenotype was severe in 219 (73%), moderate in 62 (20.67%) and mild in 19 (6.34%), based on the factor VIII bioassay. Inhibitor prevalence was 9.6% (n = 29) and seen only in the severe phenotype. Inhibitor titers ranged from 0.8 to 108.8 BU/ml. A total of 12 PWHA had low and 17 had high titers. Correlation of various clinicopathological parameters in inhibitor-positive versus negative PWHA showed significant correlation with age at onset of disease, severity of disease, age at first exposure to treatment, annual factor intake (IU/kg/year), intense treatment episodes and bleeding manifestations like central nervous system bleed and hematuria. The total study sample had blood group B in 33.34% PWHA, followed by O (27.34%), A (24.34%) and AB (15%), however, in inhibitor-positive samples, significant inhibitor formation was associated with the ABO subtype A (19/29, 65.51%).

CONCLUSIONS

Factor VIII inhibitor prevalence in PWHA receiving 'on-demand' therapy was 9.6%. Clinicopathological correlates of inhibitor development in such PWHA have been analyzed in this novel study.

Polymorphisms in the TGF-β1 (rs1982037) and IL-2 (rs2069762, rs4833248) genes are not associated with inhibitor development in Iranian patients with hemophilia A

Objectives Development of neutralizing antibodies against factor VIII is the major complication in hemophilia care which makes replacement therapies ineffective. The reports showed that inflammatory cytokines play an important role in inhibitor production. In the present study, the relationship between inhibitor development and the polymorphisms of two cytokine genes was studied in severe hemophiliac patients from Iran. Methods In this case-control study, three polymorphisms of immune regulatory genes [TGF-β (rs1982037) and IL-2 (rs2069762, rs4833248)] were analyzed in 100 Iranian hemophilia A patients divided into 55 inhibitor positive and 45 inhibitor negative patients using Tetra primer ARMS PCR, and DNA sequencing. Results The analysis of polymorphisms in the TGF-β and IL-2 genes showed no association between the genotypes and the production of inhibitors (p > 0.05). Also, comparison of allele frequencies for TGF-β and IL-2 genes between two groups indicated no significant differences associated with the development of FVIII inhibitors (p > 0.05). Discussion In contrast with some reports involving the correlation between polymorphisms of the TGF-β1 and IL-2 genes and inhibitor development in the world, no statistically significant differences in analysis of the alleles and genotypes for TGF-β and IL-2 genes were found between the inhibitor and non-inhibitor Iranian patients. Thus, other genetic markers influencing the immune response to replacement therapy in patients with hemophilia should be identified. Conclusions Regarding our results in molecular predisposition for inhibitor development, further studies of effective genetic markers are required as a prerequisite for the development of novel immunogenic therapeutic approaches in the future.

Two-incision laparoscopic appendectomy for a severe hemophilia A child patient with coagulation factor VII deficiency: Case report and review of literature

RATIONALE

The main complication of patients with severe hemophilia is recurrent bleeding events that usually affected musculoskeletal contractures. And replacement therapy methods were continuously improved to minimize adverse impacts brought by those complications. However, only several cases reported about the appendectomy for hemophilia A. We report a case of acute appendicitis treated by two-incision laparoscopy in a boy with hemophilia A and coagulation factor VII deficiency for the first time.

PATIENT CONCERNS

An 8y7m-old Chinese boy presented with half a day of right sided abdominal pain, fever, nausea, and vomiting.

DIAGNOSES

He received a computed tomography (CT) scan which revealed an enlarged appendix, thickened wall and appendiceal fecalith, and had received a conservative anti-bacterial treatment for his acute appendicitis but failed. He was diagnosed with hemophilia A and coagulation factor VII deficiency.

INTERVENTIONS

Two-incision laparoscopic appendectomy was made in success with a careful management of perioperative period. We monitored the clotting factor FVIII level and gave him a replacement therapy.

OUTCOMES

The patient had an uneventful recovery.

LESSONS

It is important to exclude intraabdominal or retroperitoneal hemorrhage in patients suffering from hemophilia and acute abdominal pain. Pre-operative evaluation of validity of the FVIII replacement therapy is another effective strategy to assess the safety and feasibility of applying an operation procedure. The two-incision laparoscopic appendectomy is an effective treatment for this kind of patients for its minimal trauma and fast recovery characteristics. Our report shows that laparoscopic appendectomy is feasible in a child suffering from hemophilia after adequate blood clotting factor replacement treatment.

A close insight to factor VIII inhibitor in the congenital hemophilia A

INTRODUCTION

Hemophilia A (HA) has an X-linked pattern of inheritance and is the most common of the hemorrhagic disorders. HA is caused by a decreased or deficiency of the functional clotting factor VIII (FVIII) and effects 1 in 5000-10,000 male births. The common treatment for hemophilia is replacement therapy by plasma-derived or recombinant FVIII. Approximately 20-30% of people with a severe type of HA develop an inhibitor and this phenomenon is the main challenge in the management of these patients. Genetic factors and environmental determinants contribute to inhibitor development. Here, the roles of various genetic and environmental factors such as the type of FVIII concentrate used, the number of exposure days, and peak treatment time will be discussed in detail. It seems this information is helpful for hematologists.

AREAS COVERED

A literature review was done in January 2016 on PubMed and Scopus using the following keywords:' h(a)emophilia A & factor VIII inhibitor', 'h(a)emophilia A & factor VIII alloantibody', 'h(a)emophilia A & inhibitor'. There was no time limitation; however, there was an English language limitation placed on the articles selected. Expert commentary: Influential genetic and environmental factors in developing inhibitors have been discussed. Most of the risk factors are related to previously untreated patients with hemophili.

The European Hematology Association Roadmap for European Hematology Research: a consensus document

The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at €23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap.The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders.The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.