Rituximab in the treatment of high responding inhibitors in severe haemophilia A

Rituximab for treating inhibitors in people with inherited severe hemophilia

BACKGROUND

Hemophilia A and B are inherited coagulation disorders characterized by a reduced or absent level of factor VIII or factor IX respectively. The severe form is characterized by a factor level less than 0.01 international units (IU) per milliliter. The development of inhibitors in hemophilia is the main complication of treatment, because the presence of these antibodies, reduces or even nullifies the efficacy of replacement therapy, making it very difficult to control the bleeding. People with inhibitors continue to have significantly higher risks of morbidity and mortality, with considerable treatment costs. Given the wide 'off-label' use of rituximab for treating people with hemophilia and inhibitors, its efficacy and safety need to be evaluated. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the efficacy and safety of rituximab for treating inhibitors in people with inherited severe hemophilia A or B.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, complied from electronic database searches and handsearching of journals and conference abstract books. We searched the reference lists of relevant articles and reviews and also searched for ongoing or unpublished studies. We also undertook further searches of other bibliographic databases and trial registries. Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 19 March 2020.

SELECTION CRITERIA

Randomized controlled trials and controlled clinical trials investigating the efficacy and safety of rituximab for treating inhibitors in people with hemophilia.

DATA COLLECTION AND ANALYSIS

No randomized controlled trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No randomized controlled trials on rituximab for treating inhibitors in people with hemophilia were identified.

AUTHORS' CONCLUSIONS

We were unable to identify any relevant trials on the efficacy and safety of rituximab for treating inhibitors in people with hemophilia. The research evidence available is from case reports and case series. Randomized controlled trials are needed to evaluate the efficacy and safety of rituximab for this condition. However, prior to the publication of any possible future randomized controlled trials, meta-analysis of case reports and case series may provide some evidence.

Low-dose immune tolerance induction for children with hemophilia A with poor-risk high-titer inhibitors: A pilot study in China

BACKGROUND

Immune tolerance induction (ITI) therapy is currently unaffordable in China. Management of hemophilia A children with high-titer inhibitor is therefore a challenge.

AIM

To describe the ITI strategy using plasma-derived factor VIII/von Willebrand factor concentrate (pdFVIII/VWF) +/- immunosuppression and to report its efficacy in children with hemophilia A having poor-risk status for ITI success.

METHODS

A prospective pilot study on children with hemophilia A having poor-risk status (all with at least inhibitor titer > 10 BU pre-ITI initiation). Patients received ~50 IU/kg FVIII every other day using domestic intermediate purity pdFVIII/VWF products, either alone or in combination with rituximab +/- prednisone.

RESULTS

Sixteen patients with median age 2.9 (range, 2.2-13.2) years and median pre-ITI inhibitor titer 30.7 (range, 10.4-128) BU were enrolled. Analysis at median 14.7 (range, 12.4-22.6) months' follow-up showed a total response rate of 87.5%. This included success (achieving inhibitor < 0.6 BU) in 13 patients (81.3%) in a median of 8.8 (range, 3.2-11.8) months, and partial success (achieving inhibitor < 5 BU but > 0.6BU) in 1 (6.3%). Compared to the pre-ITI period, the mean bleeds/month during ITI was 0.51 (64.0% reduction), and joint bleeds/month was 0.34 (64.3% reduction). This low-dose ITI strategy cost less by 70% to 87% than that for the high-dose FVIII regimen. No severe adverse events were observed.

CONCLUSION

This low-dose ITI strategy of pdFVIII/VWF +/- immunosuppression achieved relatively satisfactory outcomes in children with hemophilia A inhibitor having poor-risk status. This low-dose regimen showed economic advantages and is therefore suitable for using in China. However, further study in a larger cohort with a longer follow-up time is needed.

Rituximab for treating inhibitors in people with inherited severe hemophilia

BACKGROUND

Hemophilia A and B are inherited coagulation disorders characterized by a reduced or absent level of factor VIII or factor IX respectively. The severe form is characterized by a factor level less than 0.01 international units (IU) per milliliter. The development of inhibitors in hemophilia is the main complication of treatment, because the presence of these antibodies, reduces or even nullifies the efficacy of replacement therapy, making it very difficult to control the bleeding. People with inhibitors continue to have significantly higher risks of morbidity and mortality, with considerable treatment costs. Given the wide 'off-label' use of rituximab for treating people with hemophilia and inhibitors, its efficacy and safety need to be evaluated. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the efficacy and safety of rituximab for treating inhibitors in people with inherited severe hemophilia A or B.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, complied from electronic database searches and handsearching of journals and conference abstract books. We searched the reference lists of relevant articles and reviews and also searched for ongoing or unpublished studies. We also undertook further searches of other bibliographic databases and trial registries.Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 16 February 2017.

SELECTION CRITERIA

Randomized controlled trials and controlled clinical trials investigating the efficacy and safety of rituximab for treating inhibitors in people with hemophilia.

DATA COLLECTION AND ANALYSIS

No randomized controlled trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No randomized controlled trials on rituximab for treating inhibitors in people with hemophilia were identified.

AUTHORS' CONCLUSIONS

We were unable to identify any relevant trials on the efficacy and safety of rituximab for treating inhibitors in people with hemophilia. The research evidence available is from case reports and case series. Randomized controlled trials are needed to evaluate the efficacy and safety of rituximab for this condition. However, prior to the publication of any possible future randomized controlled trials, meta-analysis of case reports and case series may provide some evidence.

Rituximab for treating inhibitors in people with inherited severe hemophilia

BACKGROUND

Hemophilia A and B are inherited coagulation disorders characterized by a reduced or absent level of factor VIII or factor IX respectively. The severe form is characterized by a factor level less than 0.01 international units (IU) per milliliter. The development of inhibitors in hemophilia is the main complication of treatment, because the presence of these antibodies, reduces or even nullifies the efficacy of replacement therapy, making it very difficult to control the bleeding. People with inhibitors continue to have significantly higher risks of morbidity and mortality, with considerable treatment costs. Given the wide 'off-label' use of rituximab for treating people with hemophilia and inhibitors, its efficacy and safety need to be evaluated.

OBJECTIVES

To assess the efficacy and safety of rituximab for treating inhibitors in people with inherited severe hemophilia A or B.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, complied from electronic database searches and handsearching of journals and conference abstract books. We searched the reference lists of relevant articles and reviews and also searched for ongoing or unpublished studies.Date of last search: 27 January 2015.

SELECTION CRITERIA

Randomized controlled trials and controlled clinical trials investigating the efficacy and safety of rituximab for treating inhibitors in people with hemophilia.

DATA COLLECTION AND ANALYSIS

No randomized controlled trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No randomized controlled trials on rituximab for treating inhibitors in people with hemophilia were identified.

AUTHORS' CONCLUSIONS

We were unable to identify any relevant trials on the efficacy and safety of rituximab for treating inhibitors in people with hemophilia. The research evidence available is from case reports and case series. Randomized controlled trials are needed to evaluate the efficacy and safety of rituximab for this condition. However, prior to the publication of any possible future randomized controlled trials, meta-analysis of case reports and case series may provide some evidence.

Rituximab for treatment of inhibitors in haemophilia A. A Phase II study

The development of antibodies against infused factor VIII (FVIII) in patients with haemophilia A is a serious complication leading to poorly controlled bleeding and increased morbidity. No treatment has been proven to reduce high titre antibodies in patients who fail immune tolerance induction or are not candidates for it. The Rituximab for the Treatment of Inhibitors in Congenital Hemophilia A (RICH) study was a phase II trial to assess whether rituximab can reduce anamnestic FVIII antibody (inhibitor) titres. Male subjects with severe congenital haemophilia A and an inhibitor titre ≥5 Bethesda Units/ml (BU) following a FVIII challenge infusion received rituximab 375 mg/m² weekly for weeks 1 through 4. Post-rituximab inhibitor titres were measured monthly from week 6 through week 22 to assess treatment response. Of 16 subjects who received at least one dose of rituximab, three (18.8%) met the criteria for a major response, defined as a fall in inhibitor titre to <5 BU, persisting after FVIII re-challenge. One subject had a minor response, defined as a fall in inhibitor titre to <5 BU, increasing to 5-10 BU after FVIII re-challenge, but <50% of the original peak inhibitor titre. Rituximab is useful in lowering inhibitor levels in patients, but its effect as a solo treatment strategy is modest. Future studies are indicated to determine the role of rituximab as an adjunctive therapy in immune tolerisation strategies.

Inhibitor eradication with rituximab in haemophilia: where do we stand?

Rituximab is a humanized chimeric anti-CD20 monoclonal antibody initially developed for the treatment of some haematological malignancies. Thanks to its ability to rapidly and specifically deplete B cells, it has also been used in a variety of autoimmune disorders, haematological or not. In this context, during the last decade several small case series have documented successful inhibitor eradication with rituximab, alone or in combination with other immunosuppressive agents, in patients with acquired haemophilia A refractory to standard therapy. In addition, a number of investigators have recently used this agent in patients with congenital haemophilia A or B and alloantibodies refractory to first-line treatment. This article critically reviews the current knowledge on the use of rituximab in acquired haemophilia or congenital haemophilia complicated by alloantibodies, also providing treatment algorithms for the management of these conditions.

What is the Evidence for the Use of Immunomodulatory Agents to Eradicate Inhibitory Antibodies in Patients with Severe Hemophilia A Who Have Previously Failed to Respond to Immune Tolerance Induction?

An 18-year-old man has severe hemophilia A that has been complicated by a high-titer inhibitory antibody (peak 170 BU/mL). He had previously failed a trial of immune tolerance induction (ITI) using daily high-dose (100 units/kg/d) factor VIII (FVIII) for 20 months and would like to know if immunomodulatory agents, with or without another course of ITI, might eradicate the inhibitor.

Rituximab and immune tolerance in severe hemophilia A: a consecutive national cohort

SUMMARY BACKGROUND AND OBJECTIVES: he management of patients with severe hemophilia A and inhibitors to factor VIII (FVIII) resistant to standard immune tolerance is challenging. There have been recent case reports of the successful use of rituximab in up to 57% of patients as part of rescue immune tolerance regimens. Because case reports and small series are prone to the potential bias of reporting good outcomes and relatively short follow up, a consecutive cohort of all patients treated in the UK with prolonged follow up was analyzed.

METHODS

A national survey of all Comprehensive Care Haemophilia Center in the UK.

RESULTS

A total of 15 patients were reported of whom six (40%) achieved a negative inhibitor titer by Bethesda assay. Durable responses were unusual, observed in only 14% of cases. Clinically significant responses with either a negative inhibitor or an inhibitor titer < 5 BU mL(-1) and no spontaneous bleeding with FVIII replacement were observed in seven (47%) cases. Concomitant use of FVIII appeared to be important. Of the 12 patients treated with rituximab and FVIII, six (50%) achieved a negative inhibitor titer and seven (58%) had a clinically beneficial response. None of the three patients treated without FVIII responded.

CONCLUSIONS

These data suggest that the use of rituximab combined with FVIII is a potentially useful treatment for patients with inhibitors resistant to standard immune tolerance, although sustained inhibitor eradication is uncommon.

How we treat a hemophilia A patient with a factor VIII inhibitor

The most significant complication of treatment in patients with hemophilia A is the development of alloantibodies that inhibit factor VIII activity. In the presence of inhibitory antibodies, replacement of the missing clotting factor by infusion of factor VIII becomes less effective. Once replacement therapy is ineffective, acute management of bleeding requires agents that bypass factor VIII activity. Long-term management consists of eradicating the inhibitor through immune tolerance. Despite success in the treatment of acute bleeding and inhibitor eradication, there remains an inability to predict or prevent inhibitor formation. Ideally, prediction and ultimately prevention will come with an improved understanding of how patient-specific and treatment-related factors work together to influence anti–factor VIII antibody production.

The use of rituximab as an adjuvant for immune tolerance therapy in a hemophilia B boy with inhibitor and anaphylaxis to factor IX concentrate

We describe a 10-year-old severe hemophilia B boy with a stop codon mutation of exon 2 in the factor IX gene who developed high inhibitor of 70 Bethesda units (BU) from 12 months of age after exposure to prothrombin complex concentrate for 14 days. The inhibitor spontaneously disappeared within 3 months. The patient, however, exhibited anaphylactic reaction to the administration of prothrombin complex concentrate and factor IX concentrate at ages 15 and 23 months, respectively. Although recombinant activated factor VII was alternatively given, he suffered from progressive hemophilic arthropathy. At the age of 10 years, the boy underwent desensitization to factor IX concentrate and could tolerate factor IX concentrate of 40 U/kg administered on day 9 of desensitization. Unfortunately, the inhibitor of 16 BU was detected on day 6 and rapidly increased to 180 BU on day 9 of desensitization. Rituximab 375 mg/m2 per week was therefore immediately initiated on day 10 and a total of four doses were given. The inhibitor gradually decreased to 21.5 BU after the fourth dose of rituximab. The daily factor IX concentrate administration of 40 U/kg was continued for 1 month and decreased to three times per week for another month, and then to once to twice per week for the remaining 14 months of desensitization. The patient was able to attend regular school and the most recent inhibitor ranged from 4.4 to 10 BU. No proteinuria or alteration of renal function was found. In conclusion, rituximab is a helpful adjuvant to immune tolerance therapy in a hemophilia B boy with inhibitor and anaphylaxis to factor IX concentrate.

International workshop on immune tolerance induction: consensus recommendations

Although immune tolerance induction (ITI) has been used for 30 years to eliminate inhibitors and restore normal factor pharmacokinetics in patients with hemophilia, there is a paucity of scientific evidence to guide therapeutic decision-making. In an effort to provide direction for physicians and hemophilia treatment center staff members, an international panel of hemophilia opinion leaders met to develop consensus recommendations for ITI in patients with severe and mild hemophilia A and hemophilia B. These recommendations draw on the available published literature and the collective clinical experience of the group and are rated based on the level of supporting evidence.

Rituximab for the treatment of childhood chronic idiopathic thrombocytopenic purpura and hemophilia with inhibitors

Rituximab, a monoclonal chimeric antibody to the CD20 antigen, is an effective treatment for non-Hodgkin lymphomas. Moreover, rituximab has also shown efficacy in various autoimmune disorders. In this review, we will focus on the use of rituximab in childhood disorders of hemostasis associated with inhibitor formation. Although the results presented suggest that rituximab can be useful in the treatment of this subset of pediatric patients, most of the data come from isolated case reports or descriptions of small, uncontrolled series. Therefore, large, prospective, and randomized trials are needed to confirm the positive, preliminary results.

Rituximab as an adjuvant therapy to immune tolerance in a haemophilia A boy with high inhibitor titre

We report a haemophilia A boy with high inhibitor titre (170 BU) who experienced five life-threatening bleeding episodes during a one-year period from 9 to 21 months. At the age of 22 months, he received rituximab (375 mg m(-2) per dose) at one- and three-week intervals, three courses each and alternative daily treatment with factor VIII concentrate at doses of 100 units kg(-1) for 24 weeks and 50 units kg(-1) for the following 28 weeks. Although the pretreatment inhibitor level of 4.5 BU showed an anamnestic response reaching the maximum level of 200 BU at the 9th week of treatment, it gradually declined to 30 BU at the 22nd week and was constantly maintained at 25-30 BU for the following 30 weeks. Only three bleeding episodes of two haematomas and one haemarthrosis were found during the one-year treatment period. No opportunistic infection occured during this period.

Novel therapies for immune tolerance in haemophilia A

Standard treatment for an inhibitory antibody to factor VIII (FVIII) in a patient with severe congenital haemophilia A is to attempt to induce immune tolerance with high-dose FVIII, either alone or in combination with immunosuppression. Patients in whom the inhibitor is not eradicated or who have prognostic features suggestive of a poor response may be suitable for experimental approaches to immune tolerance induction. The two options that are currently under investigation in clinical practice are anti-CD20 antibody therapy using rituximab and the use of von Willebrand factor (VWF)-containing FVIII concentrate in immune tolerance regimens. Immunomodulation with rituximab has been reported to eradicate inhibitors in some patients with severe haemophilia A who have previously failed standard immune tolerance. Similarly, some patients who have failed to be tolerized with high-purity FVIII have been successfully treated with VWF-containing concentrates. Neither of these treatment modalities is supported by controlled clinical trial data, and reported observational data require confirmation. Immunomodulation via interference with B-cell/T-cell interactions by blocking CD40/CD40 ligand or a gene therapy approach using FVIII peptides in IgG heavy chain transfected into B-cell blasts has been reported to suppress inhibitors in animal models and may lead to clinically useful therapies. Further understanding of the aetiology of inhibitor formation and how FVIII leads to tolerance in some patients with an inhibitor may suggest further approaches in the future.