Prophylaxis in 10 patients with severe haemophilia A and inhibitor: different approaches for different clinical situations

Summary.  The effect of bypassing agents is not as predictable as replacement therapy with the deficient factor in inhibitor patients. Consequently, these patients have more levels of arthropathy than patients without inhibitors. Prophylaxis for inhibitor patients has gained attention over the last decade and some papers have reported that bypassing agents could work in the prevention of arthropathy. However, there is a lack data to support any specific agent or regimen or even to recommend their use in different clinical conditions. We report ten patients with haemophilia A and inhibitors treated prophylacticaly with bypassing agents (5 with FEIBA and 5 with NovoSeven). The variable conditioning the choice of one agent or the other was the intention to initiate of immune tolerance induction therapy (ITI) in the future. In 8/10 patients (4 in FEIBA group and 4 in rFVIIa group) there was a decrease of bleeding episodes while 9/10 maintained or increased their joint range of motion (ROM). In the rFVIIa prophylaxis group, prophylaxis can be considered primary since all of them had had less than one joint bleed before prophylaxis. Economic analysis showed that prophylaxis is an expensive treatment. In our experience both agents seem to be safe and effective in reducing the number of bleeds in patients with inhibitors. The anamnestic response provoked by FEIBA could be an issue while awaiting a decline in titres before ITI can be initiated and so rFVIIa may be the best option for prophylaxis in patients with inhibitors who have not yet begun ITI.     

Prompt immune tolerance induction at inhibitor diagnosis regardless of titre may increase overall success in haemophilia A complicated by inhibitors: experience of two US centres

Current guidelines recommend delaying the start of immune tolerance induction (ITI) until the inhibitor titre is <10 Bethesda units (BU) to improve success. This study was conducted to evaluate ITI outcome relative to time to start ITI from inhibitor detection irrespective of inhibitor titre. Data were retrospectively collected from two US haemophilia treatment centres (HTCs) on subjects with severe/moderate factor VIII (FVIII) deficiency with inhibitors who underwent ITI. Outcomes were defined pragmatically: success – negative inhibitor titre and ability to use FVIII concentrate for treatment/bleed prevention; partial success – inhibitor titre 1 to <5 BU with ability to use FVIII concentrate for treatment of bleeding; failure – ITI ongoing >3 years without achieving success/partial success, or ITI discontinuation. Fifty‐eight subjects were included; 32 of 39 (82%) with high‐responding inhibitor (HRI) achieved success, 7 failed. HRI subjects were subdivided based on ITI start time: 23/39 subjects started within 1 month of detection and 22/23 (96%) achieved success. Of these 23, 13 started ITI with an inhibitor titre ≥10 BU; all were successes. Eleven of 39 HRI subjects had an interval >6 months until ITI start; 7 (64%) achieved success. Time from inhibitor detection to ITI start may play a critical role in outcome. A titre ≥10 BU at ITI start did not influence outcome in subjects when ITI was initiated within 1 month of detection. Prompt ITI should be considered a viable therapeutic option in newly identified patients with inhibitors regardless of current inhibitor titre.     

The diagnosis and management of factor VIII and IX inhibitors: a guideline from the United Kingdom Haemophilia Centre Doctors Organisation

The revised UKHCDO factor (F) VIII/IX Inhibitor Guidelines (2000) are presented. A schema is proposed for inhibitor surveillance, which varies according to the severity of the haemophilia and the treatment type and regimen used. The methodological and pharmacokinetic approach to inhibitor surveillance in congenital haemophilia has been updated. Factor VIII/IX genotyping of patients is recommended to identify those at increased risk. All patients who develop an inhibitor should be considered for immune tolerance induction (ITI). The decision to attempt ITI for FIX inhibitors must be carefully weighed against the relatively high risk of reactions and the nephrotic syndrome and the relatively low response rate observed in this group. The start of ITI should be deferred until the inhibitor has declined below 10 Bethesda Units/ml, where possible. ITI should continue, even in resistant patients, where it is well tolerated and so long as there is a convincing downward trend in the inhibitor titre. The choice of treatment for bleeding in inhibitor patients is dictated by the severity of the bleed, the current inhibitor titre, the previous anamnestic response to FVIII/IX, the previous clinical response and the side-effect profile of the agents available. We have reviewed novel dose-regimens and modes of administration of FEIBA (factor VIII inhibitor bypassing activity) and recombinant activated FVII (rVIIa) and the extent to which these agents may be used for prophylaxis and surgery. Bleeding in acquired haemophilia is usually treated with FEIBA or rVIIa. Immunosuppressive therapy should be initiated at the time of diagnosis with Prednisolone 1 mg/kg/d +/- cyclophosphamide. In the absence of a response to these agents within 6 weeks, second-line therapy with Rituximab, Ciclosporin A, or other multiple-modality regimens may be considered.     

Late immune tolerance induction in haemophilia A patients

The incidence of inhibitor development in patients with severe haemophilia A is approximately 30%. Immune tolerance induction (ITI) is commonly utilized to eradicate these antibodies and is successful in 63–100% of cases. Potential predictors of a poor outcome in ITI include a high preinduction titre, high historical peak titre, older age at start of ITI and prolonged interval from diagnosis to start of ITI. The goal of this study was to characterize the outcomes of patients from our centre who have undergone late ITI, many of whom had poor prognostic features. Medical records of patients in our centre with severe/moderately severe haemophilia A (< 2% FVIII activity) and history of inhibitor were reviewed. Data were abstracted from all patients who attempted late ITI. Nine patients underwent late ITI between January 1999 and December 2011. Within this cohort, 7 (78%) patients were black, 6 (67%) were <21 years old and 4 (44%) had a family history of inhibitor. Three patients had previously received ITI unsuccessfully. To date, 4 (44%) patients are tolerized (persistently negative inhibitor titre, FVIII recovery >66% and successfully treated with FVIII products ±FVIII t^½ of > 6 h). Three patients are partially tolerized (have low responding inhibitor, variable FVIII recovery and successfully treated with FVIII products). Two patients are not tolerized. Some patients with haemophilia A and long‐standing inhibitors may benefit from ITI.     

Randomized comparison of prophylaxis and on‐demand regimens with FEIBA NF in the treatment of haemophilia A and B with inhibitors

Factor replacement therapy for the treatment of moderate to severe haemophilia A and B can be complicated by the production of inhibitory alloantibodies to factor VIII (FVIII) or factor IX. Treatment with the nanofiltered anti‐inhibitor coagulant complex, Factor Eight Inhibitor Bypassing Activity (FEIBA NF), is a key therapeutic option for controlling acute haemorrhages in patients with high‐titre inhibitors or low‐titre inhibitors refractory to replacement therapy. Given the high risk for morbidity and mortality in haemophilia patients with inhibitors to FVIII or FIX, we conducted this Phase 3 prospective study to evaluate whether prophylaxis with FEIBA NF is a safe and effective treatment option. Over a 1‐year period, 17 subjects were treated prophylactically (85 ± 15 U kg^?1 every other day) while 19 subjects were treated on demand. The median (IQR) annualized bleeding rate (ABR) during prophylaxis was 7.9 (8.1), compared to 28.7 (32.3) during on‐demand treatment, which amounts to a 72.5% reduction and a statistically significant difference in ABRs between arms (P = 0.0003). Three (17.6%) subjects (ITT) on prophylaxis experienced no bleeding episodes, whereas none treated on demand were bleeding episode‐free. Total utilization of FEIBA NF for the treatment of bleeding episodes was significantly higher during on‐demand therapy than prophylaxis (P = 0.0067). There were no differences in the rates of related adverse events between arms. This study demonstrates that FEIBA prophylaxis significantly reduces all types of bleeding compared with on‐demand treatment, and the safety of prophylaxis is comparable to that of on‐demand treatment.     

Early long-term FEIBA prophylaxis in haemophilia A patients with inhibitor after failing immune tolerance induction: A prospective clinical case series

Summary.  Persistent high-titre inhibitors after immune tolerance induction (ITI) increase the risks of haemorrhage and arthropathy, resulting in high morbidity and mortality. Long-term prophylaxis with bypassing agents may avert these risks. This study was performed to assess the effectiveness and safety of early prophylaxis with FEIBA in preventing bleeding and joint damage after failed ITI. Seven paediatric patients proceeded immediately after failed ITI to long-term FEIBA prophylaxis at 60–100 IU kg⁻¹ dosages and various dosing intervals depending upon bleeding tendency. Bleeding episodes and joint status were assessed. Thrombin generation assays (TGA) were also used to gauge treatment response. FEIBA prophylaxis was commenced at a median age of 6.0 years (range, 1.5–11.8 years) and continued for a median duration of 6.9 years (range, 0.8–17.1 years). The mean annual incidence of joint bleeding was 1.5 episodes per year with a 95% CI of 0.7–3.0 episodes per year. Muscle bleeding incidence was 0.9 episodes per year (CI, 0.6–1.2 episodes per year). No patient experienced major joint damage during prophylaxis. Median Pettersson and orthopaedic joint scores at the last follow-up evaluation were 4 (range, 0–12) and 2 (range, 0–4) respectively. Endogenous thrombin potential (ETP) measured by TGA exceeded 80% of normal after FEIBA infusion in the majority of the patients. Between regular prophylactic infusions, mean trough ETP equalled 2.6 fold of the inhibitor plasma control mean. FEIBA prophylaxis was well-tolerated without serious thrombotic or other complications. The only adverse event involved venous access. Therefore early long-term FEIBA prophylaxis is valuable in controlling bleeding and preserving joint integrity in young patients failing ITI.     

Some recent developments regarding arthropathy and inhibitors in haemophilia

Summary.  In this paper, the most recent developments on arthropathy and inhibitors in haemophilia are reviewed. Firstly, early long-term prophylaxis is strongly recommended in children with severe haemophilia. Secondly, in joint bleeds not responding to substitution of factor VIII to normal factor VIII levels angiographic embolization might be considered as a promising therapeutic option. Thirdly, recent data indicate disruption of normal development for adolescents with inhibitors. Fourthly, some case reports indicate the benefit of secondary prophylaxis with recombinant factor VIIa (rFVIIa) or factor eight inhibitor bypassing activity (FEIBA) in patients with severe haemophilia A and inhibitors. Finally, surgical procedures in haemophilia patients with factor inhibitors can be accomplished safely and effectively with FEIBA and/or rFVIIa, although the risk of complications is higher than in haemophilia patients without inhibitors.     

Optimizing management of immune tolerance induction in patients with severe haemophilia A and inhibitors: towards evidence‐based approaches

Immune tolerance induction (ITI) is the only strategy proven to eradicate persistent inhibitors in severe haemophilia A patients. Thirty years experience has shown high success rates (60–80%) with heterogeneous dose regimens and has led to the identification of clinical features that define the patients’ prognostic profile. Children with recently diagnosed inhibitors are the best candidates for ITI and adequate management may further contribute to improve the short‐ and long‐term ITI outcome. In these patients inhibitor eradication represents a cost‐effective option because it enables the restoration of FVIII prophylaxis and consequently prevents arthropathy development. Adults with long‐standing inhibitors often show bad predictors of ITI outcome, however, ITI may be considered as a suitable and cost‐effective approach in cases with frequent bleeds that are not satisfactorily controlled by by‐passing treatment and/or when orthopaedic surgery is needed. Optimal ITI regimens should be established in these different settings and randomized trials are addressing these issues. This article reviews the available literature evidence and clinical implications with current recommendations on ITI management, and highlights the issues still unsolved.     

Immune tolerance induction in the treatment of paediatric haemophilia A patients with factor VIII inhibitors

The development of an inhibitor to transfused factor VIII (FVIII) is a serious treatment-related problem in haemophiliac children. The management of patients with high titre FVIII inhibitors is difficult, and immune tolerance induction (ITI) is the only method available for the eradication of these inhibitors. The results of the ITI regimen used at the Children's Hospital of Michigan Haemophilia Treatment Center are described and discussed. ITI was attempted in 14 children with severe haemophilia A (13 high responders, one low responder), with daily doses of FVIII alone. FVIII dosage was chosen according to the patient's historical peak inhibitor titre. ITI included three phases; induction phase, dose reduction phase and maintenance phase. During the first phase, the starting dose was 50 or 100 U kg-1 d-1; during the second phase the FVIII dosage was reduced gradually to 25 U kg-1 every other day according to the inhibitor titre, FVIII recovery and/or half-life study. In the third (maintenance) phase, the children received either prophylactic therapy or episodic therapy for 12 months. The inhibitor elimination was defined as the time taken to achieve a negative inhibitor assay with no anamnestic response and normal FVIII recovery and/or normal half-life. Immune tolerance was achieved in 11 of 14 patients (79%) patients within a median time of 6 months; two children are still on therapy, three failed ITI. We observed either failure or prolongation of immune tolerance if the historical peak titre or the maximum titre during ITI was >200 BU. The success rate of our low dose ITI regimen is not different from that reported by other investigators and the inhibitor elimination time is similar to some of the studies reported previously.     

Immune tolerance induction with a high purity von Willebrand factor/VIII complex concentrate in haemophilia A patients with inhibitors at high risk of a poor response

Immune tolerance induction (ITI) is effective in approximately 70% of haemophilia patients with inhibitors. Poor prognostic factors are age >6 years, ITI started >1 year from inhibitor development, inhibitor peaks >200 BU, inhibitor titre >10 BU when ITI is started and previously failed ITI. The objective of this study was to identify the effectiveness in ITI of a high purity von Willebrand factor/factor VIII (VWF/FVIII) complex concentrate in inhibitor patients at high risk of failure. Patients with severe or moderate haemophilia A and high responding inhibitors who had at least one poor prognostic factor for ITI failure were prospectively followed-up. Success was defined by undetectable inhibitor, recovery and half life >66% of expected values. ITI dose regimens were chosen by each haemophilia centre. Seventeen haemophiliacs (16 severe, one moderate), aged 4-54 years (median 23) were followed-up for 6-71 months. Poor prognostic factors were delayed-onset ITI (n = 16), age >6 years (n = 16), previously failed ITI (n = 4), inhibitor peak >200 BU (n = 2) and inhibitor >10 BU when ITI was started (n = 4). Complete success was obtained in nine patients (53%) after 4-30 months of treatment (median 24), including two of four patients who had previously failed ITI. Seven patients achieved a partial success, with sustained low inhibitor titres (median 1.5 BU, range 1.1-2.8) but abnormal recovery and/or half-life, while the remaining patient withdrew ITI after 12 months when the inhibitor titer was still 70 BU. These findings suggest that high purity VWF/FVIII complex concentrates are effective in ITI, even in patients at high risk of failure.     

Results from a large multinational clinical trial (guardian™1) using prophylactic treatment with turoctocog alfa in adolescent and adult patients with severe haemophilia A: safety and efficacy

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prophylaxis and treatment of bleeding episodes in patients with severe haemophilia A. This multinational, open‐label, non‐controlled trial investigated the safety and efficacy of turoctocog alfa, a new rFVIII product. The primary objective was to evaluate safety. A total of 150 patients (24 adolescents and 126 adults) with severe haemophilia A (FVIII activity ≤1%), with at least 150 exposure days (EDs) to any FVIII product and no history of inhibitors were enrolled, and 146 patients (97%) completed the trial. All patients received prophylaxis with turoctocog alfa for approximately 6 months and had a mean of 85 EDs during the trial. None of the patients developed FVIII inhibitors, there were no indications of early FVIII inhibitor development and no safety concerns were identified. A total of 225 adverse events were reported in 100 (67%) patients, with the most common being events associated with dosing procedures, headaches, and nasopharyngitis. A total of 499 bleeding episodes were reported during the trial, the majority (89%) were controlled with 1–2 infusions of turoctocog alfa. Based on patient reports, the success rate (defined as ‘excellent’ or ‘good’ haemostatic response) for treatment of bleeding episodes was 81%. The overall median annualized bleeding rate was 3.7 (interquartile range: 8.7) bleeds/patient/year. In conclusion, turoctocog alfa provides a new, safe and effective alternative for prophylaxis and treatment of bleeding episodes in patients with haemophilia A.     

Prophylactic bypassing agent use before and during immune tolerance induction in patients with haemophilia A and inhibitors to FVIII

The development of high‐titre inhibitory antibodies (inhibitors) against factor VIII (FVIII) remains a challenge in the management of patients with haemophilia A (HA). Patients with high‐titre inhibitors are more likely to experience uncontrolled bleeding, physical disability from chronic arthropathy and premature death compared with those without this complication. Immune tolerance induction (ITI), utilizing repeated infusions of FVIII, is an effective therapeutic approach to eliminating inhibitory antibodies. This strategy can eradicate FVIII inhibitors, so that FVIII‐specific tolerance is induced. However, patients undergoing ITI are still vulnerable to the development of serious and/or repeated bleeding events. The efficacy of bypassing agents in preventing bleeding episodes has been widely proven in patients with HA and inhibitors to FVIII. Evidence suggests that reducing bleeding during ITI can also shorten the time to tolerance. There are concerns with the use of bypassing agents, including the cost of treatment, short half‐life, management of non‐responders and the risk of thrombosis. Despite these concerns, and the still limited evidence from prospective studies and consensus reports, the use of prophylaxis with bypassing agents during ITI has been gaining support. This review presents a rationale and current data supporting the use of prophylactic bypassing agents as effective and safe therapies to reduce the incidence of joint bleeding due to inhibitors and improve quality of life in patients with HA undergoing ITI.     

Postauthorization safety surveillance of ADVATE [antihaemophilic factor (recombinant), plasma/albumin‐free method] demonstrates efficacy,safety and low‐risk for immunogenicity in routine clinical practice

Summary. Postauthorization safety surveillance of factor VIII (FVIII) concentrates is essential for assessing rare adverse event incidence. We determined safety and efficacy of ADVATE [antihaemophilic factor (recombinant), plasma/albumin‐free method, (rAHF‐PFM)] during routine clinical practice. Subjects with differing haemophilia A severities and medical histories were monitored during 12 months of prophylactic and/or on‐demand therapy. Among 408 evaluable subjects, 386 (95%) received excellent/good efficacy ratings for all on‐demand assessments; the corresponding number for subjects with previous FVIII inhibitors was 36/41 (88%). Among 276 evaluable subjects receiving prophylaxis continuously in the study, 255 (92%) had excellent/good ratings for all prophylactic assessments; the corresponding number for subjects with previous FVIII inhibitors was 41/46 (89%). Efficacy of surgical prophylaxis was excellent/good in 16/16 evaluable procedures. Among previously treated patients (PTPs) with >50 exposure days (EDs) and FVIII ≤2%, three (0.75%) developed low‐titre inhibitors. Two of these subjects had a positive inhibitor history; thus, the incidence of de novo inhibitor formation in PTPs with FVIII ≤2% and no inhibitor history was 1/348 (0.29%; 95% CI, 0.01–1.59%). A PTP with moderate haemophilia developed a low‐titre inhibitor. High‐titre inhibitors were reported in a PTP with mild disease (following surgery), a previously untreated patient (PUP) with moderate disease (following surgery) and a PUP with severe disease. The favourable benefit/risk profile of rAHF‐PFM previously documented in prospective clinical trials has been extended to include a broader range of haemophilia patients, many of whom would have been ineligible for registration studies.     

Real‐world experience with use of Antihemophilic Factor (Recombinant), PEGylated for prophylaxis in severe haemophilia A

Introduction

Prophylaxis with extended half‐life factor VIII (FVIII) is approved for haemophilia A, but data regarding routine clinical use are limited.

Aim

To assess real‐world experience of ADYNOVATE^® (Antihemophilic Factor (Recombinant), PEGylated prophylaxis in children and adults with haemophilia A.

Methods

A retrospective chart review was conducted in three US haemophilia treatment centres. Records of all patients who began Adynovate prophylaxis in routine clinical practice were identified. Demographic, clinical and patient‐reported information beginning 6 months before initiation of Adynovate until the record review was analysed.

Results

Fifteen patients (aged 9 months to 28 years), with median 9 months’ use of Adynovate (range 1‐15 months), were identified. All had switched from another prophylactic regimen, 13 (87%) from standard half‐life recombinant FVIII. Nine (60%) patients had ≥1 bleed within 6 months preswitch. The most frequent reason for switching was to reduce infusion frequency (14 patients). After switching, infusion frequency reduced for 13 patients, and overall weekly factor consumption decreased by 19%. Eight (53%) patients had no bleeds postswitch, three (20%) had spontaneous joint bleeds (vs four pre‐switch), and three (20%) had only mild traumatic bleeds. Patient/parental satisfaction with Adynovate was documented as positive in 13 of 15 (87%) cases; 2 patients were not satisfied and discontinued Adynovate. No adverse events were considered related to Adynovate.

Conclusion

In patients who switched from a standard half‐life FVIII to Adynovate prophylaxis in routine clinical practice, bleeding control was generally improved or maintained, with a lower infusion frequency and factor consumption in most patients.     

Matching-adjusted indirect comparison of bleeding outcomes in severe haemophilia A: Comparing valoctocogene roxaparvovec gene therapy,emicizumab prophylaxis,and FVIII replacement prophylaxis

Introduction

Head-to-head evaluation of valoctocogene roxaparvovec, the first gene therapy approved for haemophilia A, with emicizumab is not available. Therefore, phase 3 trial data were indirectly compared.

Aim

To compare bleeding rates in trials evaluating 6 × 10¹³ vg/kg valoctocogene roxaparvovec (GENEr8-1; NCT03370913), 1.5 mg/kg emicizumab dosed every week (HAVEN 3; NCT02847637), and FVIII prophylaxis (270–902) in participants with severe haemophilia A (FVIII ≤1 IU/dL).

Methods

Valoctocogene roxaparvovec versus emicizumab and FVIII prophylaxis as used in 270–902 versus emicizumab cross-trial comparisons were performed using matching-adjusted indirect comparison (MAIC). Individual participant data from GENEr8-1 and 270–902 were weighted to equalise aggregate participant baseline characteristics from HAVEN 3. After MAIC weighting, annualised bleeding rates (ABR) and proportions of participants without bleeds were compared for treated bleeds, all bleeds, treated joint bleeds, and treated spontaneous bleeds.

Results

After MAIC weighting, ABR for all bleeds was statistically significantly lower with valoctocogene roxaparvovec than emicizumab (rate ratio [95% CI], .55 [.33–.93]). Additionally, significantly higher proportions of participants had no treated joint bleeds (odds ratio [95% CI], 2.75 [1.20–6.31]) and no treated bleeds (3.25 [1.53–6.90]) with valoctocogene roxaparvovec versus emicizumab. When compared with the mainly standard half-life FVIII prophylaxis regimens in 270–902, mean ABRs (except for all bleeds) were significantly lower, and significantly higher proportions reported 0 bleeds for all outcomes with emicizumab.

Conclusion

Valoctocogene roxaparvovec provided generally lower bleeding rates and higher probability of no bleeds, including treated joint bleeds, than emicizumab. Emicizumab was more effective than FVIII prophylaxis regimens used in 270–902.     

Persistent factor VIII inhibitors and orthopaedic complications in children with severe haemophilia A

Summary. Persistence of inhibitors against factor VIII (FVIII) may be a risk factor that increases physical disability in haemophilia A (HA) patients. This study aimed to evaluate prevalence of FVIII inhibitors in previously treated children with severe HA and the impact of persistent inhibitors on knee joint status and lumbar bone mineral density (BMD). Fifty children with severe HA, FVIII <1%; aged 5–16 years were enrolled in this study; they received plasma‐derived FVIII on‐demand treatment for 50–250 exposure days (EDs). Inhibitors were checked at basal visit and were followed up for 1 year, using Bethesda assay. Cross‐sectional clinical scoring and radiological evaluation of the knee joint (by Arnold‐Hilgartner staging and Pettersson score), along with lumbar BMD by Dual Energy X‐ray Absorptiometry (DEXA) were performed. Patients with persistent inhibitors for 1 to 5 years, median 2.5 years, were 10 (20%). Six had high titre and none of them had completely normal knees, seven had advanced knee arthropathy and six had low lumbar BMD in comparison to 2 and 8 of the 40 patients without inhibitors respectively (P < 0.05). Persistence of inhibitors for more than 2 years without immuno‐prophylaxis was a risk factor for joint damage. Low lumbar BMD was found in 88.9% of patients with stages four and five knee arthropathy and in 66.7% of patients with positive hepatitis C. Severe HA children in this Egyptian study had a relatively low prevalence of persistent FVIII inhibitors, which, if not treated, may increase the risk of knee arthropathy and lumbar osteopenia.     

Recombinant factor VIII Fc fusion protein for immune tolerance induction in patients with severe haemophilia A with inhibitors—A retrospective analysis

Introduction

Immune tolerance induction (ITI) is the gold standard for eradication of factor VIII inhibitors in severe haemophilia A; however, it usually requires treatment for extended periods with associated high burden on patients and healthcare resources.

Aim

Review outcomes of ITI with recombinant factor VIII Fc fusion protein (rFVIIIFc) in patients with severe haemophilia A and high‐titre inhibitors.

Methods

Multicentre retrospective chart review of severe haemophilia A patients treated with rFVIIIFc for ITI.

Results

Of 19 patients, 7 were first‐time ITI and 12 were rescue ITI. Of 7 first‐time patients, 6 had at least 1 high‐risk feature for ITI failure. Four of 7 first‐time patients were tolerized in a median of 7.8 months. The remaining 3 patients continue on rFVIIIFc ITI. Of 12 rescue patients, 7 initially achieved a negative Bethesda titre (≤0.6) in a median of 3.3 months, 1 had a decrease in Bethesda titre and continues on rFVIIIFc ITI and 4 have not demonstrated a decrease in Bethesda titre. Of these 4, 3 continue on rFVIIIFc ITI and 1 switched to bypass therapy alone. Two initially responsive patients transitioned to other factors due to recurrence. Overall, 16 of 19 patients remain on rFVIIIFc (prophylaxis or ITI). For those still undergoing ITI, longer follow‐up is needed to determine final outcomes. No adverse events reported.

Conclusions

Recombinant factor VIII Fc fusion protein demonstrated rapid time to tolerization in high‐risk first‐time ITI patients. For rescue ITI, rFVIIIFc showed therapeutic benefit in some patients who previously failed ITI with other products. These findings highlight the need to further evaluate the use of rFVIIIFc for ITI.     

Assessing the benefits of FEIBA prophylaxis in haemophilia patients with inhibitors

Summary. Prophylaxis with concentrates of factor VIII has become the standard of care for patients with severe haemophilia A because of its ability to prevent joint and other bleeding events. Recent evidence suggests that the prophylactic use of bypassing therapy – activated prothrombin complex concentrate (aPCC) and recombinant activated factor VII (rFVIIa) – provides similar benefits to haemophilia patients with inhibitors. To assess the efficacy and safety of prophylaxis with the aPCC FEIBA, a meta‐analysis was conducted of six studies and a total of 34 inhibitor patients. The mean prophylactic dose was 78.5 U kg^?1, typically infused three to four times weekly. A total of 31 of 33 patients (94%) for whom bleeding data were available prior to prophylaxis experienced a decrease in the rate of haemorrhage, albeit minor in some patients, and, regardless of the type of haemorrhage measured, had on average a 63.9% reduction in bleeding episodes during FEIBA prophylaxis. In the three studies that specifically assessed all joint bleeding, the 18 patients evaluated experienced an average reduction in annual joint bleeding of 74% while on prophylactic regimens. Among the four patients in this group who received concurrent immune tolerance induction and the 14 patients treated with prophylaxis only, annual joint bleeding decreased by an average of 79% and 78%, respectively. Anamnesis following FEIBA exposure was observed in some patients but had no impact on prophylactic efficacy. No thrombotic or other complications were reported. These results suggest that the prophylactic administration of FEIBA can be an effective and safe method for reducing bleeding events in patients with haemophilia A and inhibitors.     

Prophylaxis in haemophilia patients with inhibitors

Summary.   The presence of high titre inhibitors makes the treatment of bleeding episodes in haemophilia patients difficult and increases the risk of uncontrollable bleeding and disability, despite optimum on-demand treatment with bypassing agents. The inability to effectively control joint bleeding leads to progressive joint disease in many patients with inhibitors. Significant mobility impairments are far more prevalent in patients with inhibitors than in those without inhibitors. Emerging data suggest that prophylaxis using bypassing agents may be effective and safe in reducing the incidence of joint bleeding during immune tolerance induction (ITI), and for patients who failed ITI or who were never candidates for ITI. Only controlled clinical trials will ultimately demonstrate whether prophylaxis can prevent joint bleeding and damage, and improve quality of life in patients with inhibitors. This article will review the published data on the use of bypassing agents in the prevention of bleeding, and will discuss ongoing clinical prophylaxis trials in inhibitor patients.