Aquatic exercise in patients with haemophilia: Electromyographic and functional results from a prospective cohort study

INTRODUCTION

Recurrent joint bleeds in haemophilia patients often cause musculoskeletal changes leading to functional capacity impairment.

AIM

In this study, we assessed the effects of aquatic activities performed to improve functional capacity in these patients.

METHODS

The interventional protocol consisted of 24 hydrotherapy sessions during three months, in comparison with 24 swimming sessions. The pre- and post-intervention assessment consisted of Functional Independence Score, haemophilia joint health score (HJHS), Pediatric Haemophilia Activities List (PedHAL), surface electromyography (SEMG) of thigh muscles to assess muscle electric activity, and load cell on extensor and flexor thigh muscles to evaluate muscular strength.

RESULTS

Forty-seven haemophilia patients were enrolled in this study, and 32 (23 severe haemophilia A, one moderate haemophilia A and 8 severe haemophilia B), median age 12y (6 to 40y), concluded the aquatic intervention. We observed a statistically significant increase with substantial improvement in functional capacity in the pre- and post-intervention evaluation of hydrotherapy in comparison with the swimming protocol, with HJHS (p = .006 and p = .001 respectively), PedHAL (Sum score) (p = .022 and p = .001) and score FISH (p = .021). The swimming group revealed significant improvements in muscular strength, in all muscles tested (p = .005 and p = .001). SEMG signal amplitude reached significantly higher levels in all muscles evaluated after both interventions except for the vastus medialis (right) in the hydrotherapy group.

CONCLUSION

Our results concluded that both swimming and hydrotherapy were associated with physical improvement in haemophilia patients; however, only hydrotherapy lead to a more significant improvement in functional capacity.

ASH ISTH NHF WFH 2021 guidelines on the management of von Willebrand disease

BACKGROUND

von Willebrand disease (VWD) is a common inherited bleeding disorder. Significant variability exists in management options offered to patients.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH), the International Society on Thrombosis and Haemostasis (ISTH), the National Hemophilia Foundation (NHF), and the World Federation of Hemophilia (WFH) are intended to support patients, clinicians, and health care professionals in their decisions about management of VWD.

METHODS

ASH, ISTH, NHF, and WFH formed a multidisciplinary guideline panel. Three patient representatives were included. The panel was balanced to minimize potential bias from conflicts of interest. The University of Kansas Outcomes and Implementation Research Unit and the McMaster Grading of Recommendations Assessment, Development and Evaluation (GRADE) Centre supported the guideline development process, including performing and updating systematic evidence reviews (through November 2019). The panel prioritized clinical questions and outcomes according to their importance to clinicians and patients. The panel used the GRADE approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 12 recommendations and outlined future research priorities.

CONCLUSIONS

These guidelines make key recommendations regarding prophylaxis for frequent recurrent bleeding, desmopressin trials to determine therapy, use of antiplatelet agents and anticoagulant therapy, target VWF and factor VIII activity levels for major surgery, strategies to reduce bleeding during minor surgery or invasive procedures, management options for heavy menstrual bleeding, management of VWD in the context of neuraxial anesthesia during labor and delivery, and management in the postpartum setting.

Knee radiosynovectomy with 153Sm-hydroxyapatite compared to 90Y-hydroxyapatite: initial results of a prospective trial

INTRODUCTION

Radiosynovectomy (RS) with ⁹⁰Y-hydroxyapatite (⁹⁰Y-HyA) aims to control knee hemarthrosis in hemophiliac patients to prevent secondary arthropathy. However, knee RS using ¹⁵³Sm-hydroxyapatite (¹⁵³Sm-HyA) is considered less suitable due to the lower average soft tissue range and energy of ¹⁵³Sm for large joints, such as the knees.

PURPOSE

The objective of this investigation was to assess the efficacy and safety of knee RS with ¹⁵³Sm-HyA, compared to ⁹⁰Y-HyA.

METHODS

Forty patients were prospectively assigned to undergo knee RS with ¹⁵³Sm-HyA (n = 19) or with ⁹⁰Y-HyA (n = 21). The frequency of hemarthrosis episodes before and after treatment were compared.

RESULTS

After six months of knee RS, ¹⁵³Sm-HyA and ⁹⁰Y-HyA promoted a similar reduction of hemarthrosis episodes (50% and 66.7%, respectively). However, after 12 months of knee RS, the reduction of hemarthrosis episodes was significantly (p = 0.037) higher using ¹⁵³Sm-HyA (87.5%) compared to ⁹⁰Y-HyA (50.0%). This discrepancy was more pronounced (p = 0.002) for ¹⁵³Sm-HyA compared to ⁹⁰Y-HyA in adults/adolescents.

CONCLUSION

Knee radiosynovectomy with ¹⁵³Sm-HyA is safe, reduces hemarthrosis episodes after 12 months of treatments, especially in adults/adolescents and even with grades III/IV arthropathy, similar to ⁹⁰Y-HyA. ⁹⁰Y-HyA seems to promote better hemarthrosis control in small children.

Long-term safety and sustained efficacy for up to 5 years of treatment with recombinant factor IX Fc fusion protein in subjects with haemophilia B: Results from the B-YOND extension study

INTRODUCTION

Recombinant factor IX Fc fusion protein (rFIXFc) has demonstrated efficacy for treatment of haemophilia B in the Phase 3 B-LONG and Kids B-LONG studies. However, long-term rFIXFc safety and efficacy data have not yet been reported.

AIM

To report long-term rFIXFc safety and efficacy in subjects with haemophilia B.

METHODS

B-YOND (NCT01425723) was an open-label extension for eligibl previously treated subjects who completed B-LONG or Kids B-LONG. Subjects received ≥1 treatment regimen: weekly prophylaxis (WP), individualized interval prophylaxis (IP), modified prophylaxis or episodic treatment. Subjects could switch regimens at any time. The primary endpoint was inhibitor development.

RESULTS

Ninety-three subjects from B-LONG and 27 from Kids B-LONG (aged 3-63 years) were enrolled. Most subjects received WP (B-LONG: n = 51; Kids B-LONG: n = 23). For subjects from B-LONG, median (range) treatment duration was 4.0 (0.3-5.4) years and median (range) number of exposure days (EDs) was 146 (8-462) EDs. Corresponding values for paediatric subjects were 2.6 (0.2-3.9) years and 132 (50-256) EDs. No inhibitors were observed (0 per 1000 subject-years; 95% confidence interval, 0-8.9) and the overall rFIXFc safety profile was consistent with prior studies. Annualized bleed rates remained low and extended-dosing intervals were maintained for most subjects. Median dosing interval for the IP group was approximately 14 days for adults and adolescents (n = 31) and 10 days for paediatric subjects (n = 5).

CONCLUSIONS

B-YOND results confirm the long-term (up to 5 years, with cumulative duration up to 6.5 years) well-characterized safety and efficacy of rFIXFc treatment for haemophilia B.

Angiogenesis-Related Genes in Endothelial Progenitor Cells May Be Involved in Sickle Cell Stroke

Background The clinical aspects of sickle cell anemia (SCA) are heterogeneous, and different patients may present significantly different clinical evolutions. Almost all organs can be affected, particularly the central nervous system. Transient ischemic events, infarcts, and cerebral hemorrhage can be observed and affect ≈25% of the patients with SCA. Differences in the expression of molecules produced by endothelial cells may be associated with the clinical heterogeneity of patients affected by vascular diseases. In this study, we investigated the differential expression of genes involved in endothelial cell biology in SCA patients with and without stroke. Methods and Results Endothelial progenitor cells from 4 SCA patients with stroke and 6 SCA patients without stroke were evaluated through the polymerase chain reaction array technique. The analysis of gene expression profiling identified 29 differentially expressed genes. Eleven of these genes were upregulated, and most were associated with angiogenesis (55%), inflammatory response (18%), and coagulation (18%) pathways. Downregulated expression was observed in 18 genes, with the majority associated with angiogenesis (28%), apoptosis (28%), and cell adhesion (22%) pathways. Remarkable overexpression of the MMP1 (matrix metalloproteinase 1) gene in the endothelial progenitor cells of all SCA patients with stroke (fold change: 204.64; P=0.0004) was observed. Conclusions Our results strongly suggest that angiogenesis is an important process in sickle cell stroke, and differences in the gene expression profile of endothelial cell biology, especially MMP1, may be related to stroke in SCA patients.

Routine clinical care data for population pharmacokinetic modeling: the case for Fanhdi/Alphanate in hemophilia A patients

Fanhdi/Alphanate is a plasma derived factor VIII concentrate used for treating hemophilia A, for which there has not been any dedicated model describing its pharmacokinetics (PK). A population PK model was developed using data extracted from the Web-Accessible Population Pharmacokinetic Service-Hemophilia (WAPPS-Hemo) project. WAPPS-Hemo provided individual PK profiles for hemophilia patients using sparse observations as provided in routine clinical care by hemophilia centers. Plasma factor activity measurements and covariate data from hemophilia A patients on Fanhdi/Alphanate were extracted from the WAPPS-Hemo database. A population PK model was developed using NONMEM and evaluated for suitability for Bayesian forecasting using prediction-corrected visual predictive check (pcVPC), cross validation, limited sampling analysis and external evaluation against a population PK model developed on rich sampling data. Plasma factor activity measurements from 92 patients from 12 centers were used to derive the model. The PK was best described by a 2-compartment model including between subject variability on clearance and central volume, fat free mass as a covariate on clearance, central and peripheral volumes, and age as covariate on clearance. Evaluations showed that the developed population PK model could predict the PK parameters of new individuals based on limited sampling analysis and cross and external evaluations with acceptable precision and bias. This study shows the feasibility of using real-world data for the development of a population PK model. Evaluation and comparison of the model for Bayesian forecasting resulted in similar results as a model developed using rich sampling data.

Gene Therapy: Paving New Roads in the Treatment of Hemophilia

Hemophilia is a monogenic disease with robust clinicolaboratory correlations of severity. These attributes coupled with the availability of experimental animal models have made it an attractive model for gene therapy. The road from animal models to human clinical studies has heralded significant successes, but major issues concerning a previous immunity against adeno-associated virus and transgene optimization remain to be fully resolved. Despite significant advances in gene therapy application, many questions remain pertaining to its use in specific populations such as those with factor inhibitors, those with underlying liver disease, and pediatric patients. Here, the authors provide an update on viral vector and transgene improvements, review the results of recently published gene therapy clinical trials for hemophilia, and discuss the main challenges facing investigators in the field.

Extending recombinant factor IX Fc fusion protein dosing interval to 14 or more days in patients with hemophilia B

BACKGROUND

In the phase 3 B-LONG study (NCT01027364), prophylaxis with recombinant factor IX Fc fusion protein (rFIXFc) every 7 to >14 days was associated with low annualized bleed rates (ABRs) in males aged ≥12 years with severe hemophilia B. The long-term safety and efficacy of rFIXFc prophylaxis was confirmed in the B-YOND study (NCT01425723), an extension of the B-LONG clinical trial.

OBJECTIVE

The aim of this post-hoc analysis was to evaluate the efficacy of a ≥14-day rFIXFc dosing interval in patients treated prophylactically during B-LONG or B-YOND.

METHODS

The analysis included 22 patients aged ≥12 years who received prophylactic rFIXFc with a ≥14-day dosing interval at any time during B-LONG or B-YOND up until the second interim analysis of B-YOND (September 2015).

RESULTS

The median (interquartile range [IQR]) rFIXFc exposure on the ≥14-day dosing interval was 3.4 (1.8-4) years. Patients treated with a ≥14-day dosing interval were well controlled with a median (IQR) overall ABR of 1.6 (0.6-2.7) and a median (IQR) spontaneous ABR of 0.7 (0.3-1.1) in 18 evaluable patients. A rFIXFc dosing interval of ≥14 days was well tolerated, with no new safety concerns identified.

CONCLUSION

Most patients on rFIXFc prophylaxis, with a dosing interval of ≥14 days, remained well controlled; ABRs were consistent with those reported in the overall study population. A ≥14-day dosing interval can be utilized in some well controlled individuals and reduces the burden imposed by frequent prophylactic injections while maintaining adequate bleed suppression.

Long-term safety and efficacy of turoctocog alfa in prophylaxis and treatment of bleeding episodes in severe haemophilia A: Final results from the guardian 2 extension trial

INTRODUCTION

Turoctocog alfa is a recombinant factor VIII (FVIII) molecule, approved for treatment and prophylaxis of bleeding in patients with haemophilia A. In the guardian 1 (adolescents/adults) and guardian 3 (children) phase 3 trials, turoctocog alfa demonstrated a favourable efficacy and safety profile. Guardian 1 or 3 completers could enrol in the guardian 2 extension. Final guardian 2 results are reported here.

AIM

Investigate long-term safety and efficacy of turoctocog alfa administered for prophylaxis and treatment of bleeds.

METHODS

In this phase 3b open-label trial, previously treated males of all ages with severe haemophilia A received prophylaxis regimens of turoctocog alfa or on-demand treatment of bleeds. The primary safety endpoint was frequency of FVIII inhibitor development. Efficacy endpoints included annualized bleeding rate (ABR) during prophylaxis, haemostatic response in treatment of bleeds and number of injections required to treat bleeds.

RESULTS

Overall, 213 patients were dosed with turoctocog alfa; 207 patients received prophylaxis; 19 received on-demand treatment. No FVIII inhibitors (≥0.6 BU) were reported. For all patients on prophylaxis, overall median ABR was 1.37 bleeds/y; success rate for treatment of bleeds was 90.2%; and 88.2% of bleeds were controlled with 1-2 injections of turoctocog alfa. For the on-demand regimen, overall median ABR was 30.44 bleeds/y; success rate for treatment of bleeds was 96.7%; and 94.9% of bleeds were controlled with 1-2 injections of turoctocog alfa.

CONCLUSION

Extended use of turoctocog alfa is safe and effective for prevention and treatment of bleeding episodes in previously treated patients with haemophilia A across all ages.

Early in vivo anticoagulation inhibits the angiogenic response following hindlimb ischemia in a rodent model

Emerging findings have demonstrated the critical role of blood clotting factors in the formation and stabilization of embryonic blood vessels. Whether a similar role is true during post-natal angiogenesis remains to be determined. Here we sought to determine whether the suppression of thrombin generation with anticoagulant drugs at doses routinely used for therapeutic purposes would affect the angiogenesis pattern following hindlimb ischemia in rats. Animals were treated with r- hirudin or enoxaparin within six hours post induction of hindlimb ischemia, whereas two other groups received oral anticoagulation warfarin beginning at day 3 post-ischemia or saline (as control). The revascularization anatomical and functional responses were evaluated 30 days following tissue ischemia. Chronic administration of the drugs resulted in stable anticoagulation in all animals throughout the experiment. Animals that received drugs with fast anticoagulation effects (i.e. r-hirudin and enoxaparin) presented a significant decrease in capillary density and capillary-to-myocyte ratio compared to control animals. These effects were not associated with changes in relative perfusion of the hindlimb at steady state. These anti-angiogenic effects occur in a time-dependent manner, since delayed inhibition of coagulation (> 72 hours) presents no adverse effect on the angiogenic response. We conclude that the use of anticoagulant drugs immediately after tissue ischemia induction hampers in vivo angiogenic response in a rodent hindlimb ischemia model.

Thalidomide for the Treatment of Gastrointestinal Bleeding Due to Angiodysplasia in a Patient with Glanzmann's Thrombasthenia

Angiodysplasia is a frequent cause of persistent gastrointestinal (GI) hemorrhage in elderly patients. Although GI bleeding isn't the most common manifestation in patients with bleeding disorders, when present, it represents a challenging complication. We describe a 62-year-old patient with Glanzmann's thrombasthenia, who used thalidomide for severe and recurrent GI bleeding. For 6 months, the patient experienced temporary control of GI bleeding with thalidomide in a daily oral dose of 100 mg. The anti-angiogenic effects of thalidomide have recently been explored by several groups, particularly in the management of bleeding from angiodysplasia, including cases with von Willebrand disease. Here, we review the relevant descriptions of the use of thalidomide in this situation, and also discuss potential reasons why we observed only a temporary control of the GI bleeding in our patient, such as the use of low-dose regimen due to limitations posed by thalidomide side effects.

Evaluation of the immature platelet fraction contribute to the differential diagnosis of hereditary, immune and other acquired thrombocytopenias

The differential diagnosis of immune (ITP) and hereditary macrothrombocytopenia (HM) is key to patient management. The immature platelet fraction (IPF) represents the subset of circulating platelets with higher RNA content, and has been shown to distinguish hypo- from hyperproliferative thrombocytopenias. Here we evaluated the diagnostic accuracy of IPF in the differential diagnosis between HM and other thrombocytopenias in a population of patients with post-chemotherapy thrombocytopenia (n = 56), bone marrow failure (n = 22), ITP (n = 105) and HM (n = 27). TPO levels were also measured in HM and ITP matched for platelet counts. Platelet counts were similar in all patient groups. Higher IPF values were observed in both ITP (12.3%; 2.4–65.6%) and HM (29.8%; 4.6–65.9%) compared to hypoproliferative thrombocytopenias. IPF values were also higher in HM compared to ITP, yielding a diagnostic accuracy of 0.80 (95%CI 0.70–0.90; P < 0.0001) to distinguish these two conditions. Intra- and inter-assays reproducibility of IPF in HM patients revealed that this is a stable parameter. In conclusion, IPF is increased in HM compared to both ITP and other thrombocytopenias and contributes to the differentiation between ITP and HM. Further studies are warranted to understand the biological rationale of these findings and to its incorporation in diagnostic algorithms of HM.

Comparing the burden of illness of haemophilia between resource-constrained and unconstrained countries: the São Paulo-Toronto Hemophilia Study

INTRODUCTION

Although the regular replacement of clotting factor concentrates (prophylaxis) has been well established as the standard of care for severe haemophilia, the high cost of factor concentrates has limited access to prophylaxis in countries with under-developed or developing economies.

AIMS

We studied the health gap that could be addressed by providing unlimited access to clotting factor concentrates with implementation of long-term prophylaxis initiated from an early age in life.

METHODS

We performed a cross-sectional study of a random, representative sample of boys with moderate and severe haemophilia at three haemophilia treatment centres in Sao Paulo, Brazil, and one centre in Toronto, Canada.

RESULTS

Canadian subjects were more often treated with prophylaxis, and began treatment at an earlier age. Fewer Canadian subjects had bleeds within the preceding 6 months (19 vs. 34, P = 0.003). Canadian subjects had lower (better) Pettersson radiographic scores (1.5 vs. 6.0, P = 0.0016), lower (better) Hemophilia Joint Health Scores (5.5 vs. 10.5, P = 0.0038), higher (better) Activity Scale for Kids scores (96.6 vs. 92.0, P = 0.033), more time spent in vigorous activity, and higher (better) social participation scores.

CONCLUSIONS

Our findings suggest that increasing access to clotting factor concentrates for young boys with severe haemophilia is a global imperative.

Validity of the Portuguese CHO-KLAT in Brazil

INTRODUCTION

It is essential to assess the health-related quality of life outcomes of boys with haemophilia in Brazil. The Canadian Haemophilia Outcomes-Kids Life Assessment Tool (CHO-KLAT) was recently adapted for this population.

AIM

To test the construct validity of the Portuguese version of the CHO-KLAT.

METHODS

We recruited 50 boys, with moderate [factor VIII (FVIII) level 1-5%] or severe (FVIII level <1%) haemophilia, to participate in a descriptive study to establish a baseline understanding of the current status of boys with haemophilia in Brazil. All boys were required to complete the Brazilian CHO-KLAT and Brazilian Pediatric Quality of Life Inventory (PedsQL) by self-report. We examined the correlation between the CHO-KLAT and PedsQL scores to establish the construct validity of the Brazilian version of the CHO-KLAT.

RESULTS

We obtained CHO-KLAT and PedsQL data from 35 boys with severe haemophilia and 15 with moderate haemophilia. They ranged in age from 7.3 to 18.0 years, with a mean of 13.0 years. They reported a mean CHO-KLAT score of 72.3 (range = 44.1-93.9). The mean PedsQL score was 79.9 (range = 45.7-96.7), with physical health (mean of 83.9) being better than psychosocial health (77.8). The Pearson's correlation between CHO-KLAT and PedsQL was 0.47 respectively (P < 0.001). The CHO-KLAT had a moderate and inverse relationship with the degree to which they were bothered by their haemophilia (ρ = -0.53), while the PedsQL had a weaker relationship (ρ = -0.27).

CONCLUSION

The results confirm the validity of the Portuguese version of the CHO-KLAT. This measure is now available for clinical trials in boys with haemophilia in Brazil.

Updates from guardian™: a comprehensive registration programme

Turoctocog alfa is an approved B-domain truncated recombinant factor VIII concentrate for adults and children with haemophilia A. Clinical data for turoctocog alfa have been reported from the guardian(™) 1, guardian(™) 2 and guardian(™) 3 phase III trials. guardian(™) 1 and guardian(™) 3 phase III trials enrolled 150 adolescents/adults (≥ 12 yr), and 63 children (<12 yr), respectively, with previously treated severe haemophilia A and no history of inhibitors; 188 of these patients continued into the ongoing guardian(™) 2 extension trial. In the three trials, patients have received prophylaxis with turoctocog alfa three times weekly or every second day, with breakthrough bleeds resolved to an expected postinjection level of ≥ 0.50 IU/mL. No safety concerns have arisen, and no patients have developed confirmed inhibitors (primary endpoint). Indeed, no confirmed inhibitors have been detected in >200 patients treated for a cumulative total of >54,000 exposure days in the phase III trials. Pooled efficacy data show a favourable long-term effect of turoctocog alfa on annualised bleeding rate and a success rate for haemostatic response of 86%; 90% of bleeds were resolved with 1-2 doses. This article reviews the clinical development of turoctocog alfa with reference to the guardian(™) clinical programme, describing results obtained to date and ongoing trials.

Transgene-host cell interactions mediate significant influences on the production, stability, and function of recombinant canine FVIII

Recombinant FVIII manufacturing is characterized by poor product stability and low yields. Codon-optimization of transgenes accelerates translation by exploiting the synonymous codon usage bias of a species. However, this can alter the performance of the final product. Additionally, the effects of transgene design across diverse cell types are not well understood and are of interest for next-generation protein and gene therapies. To investigate the effects of transgene design across different host cells, B-domain-deleted (BDD) and modified codon-optimized (CO-N6) transgenes were inserted via lentiviral delivery into cBOECs, HEK293T, and MDCK cells. The CO-N6 cFVIII transgene produced threefold more protein per transgene in HEK293T cells, and sixfold more protein in the two canine cell lines. However, pharmacokinetic analysis in hemophilia A dogs demonstrated that cFVIII produced from cBOECs transduced with the CO-N6 transgene had significantly reduced in vivo recovery. Furthermore, this product showed reduced in vitro stability and activity on thrombin activation versus the BDD product. This trend was reversed in HEK293T lines. Overall, our results demonstrate the need for an integrated approach that not only assesses protein expression levels but also considers the influence that host-cells have on preserving the molecular and biochemical properties of the naturally occurring FVIII.

Allergic reaction in a cohort of haemophilia A patients using plasma-derived factor VIII (FVIII) concentrate is rare and not necessarily triggered by FVIII

In contrast to haemophilia B, allergic manifestations are rare complications in haemophilia A (HA) patients treated with factor VIII (FVIII) concentrates. Nevertheless, it can be serious and hamper replacement therapy in these cases. The aims of this study were to evaluate the frequency of allergic reaction in a cohort of HA patients treated only with plasma-derived FVIII (pdFVIII) concentrates, and assess the possible immune mechanisms involved. History of allergic reaction was retrospectively assessed. Patients with allergic manifestations were followed, and had plasma samples collected in different timepoints in relation to the allergic episode. These samples were analysed for the presence of inhibitor and anti-FVIII immunoglobulins subclasses. Three of 322 HA patients (0.9%) developed allergic reaction after exposure to pdFVIII products during the last 15 years in our centre. The first patient, with severe HA, without inhibitor, had anti-pdFVIII IgE and IgG4, but no anti-recombinant FVIII (rFVIII) IgE. The second patient, with severe HA, and high-responding inhibitor, presented allergic manifestation with both, pdFVIII concentrate and activated prothrombin complex concentrate. Although anti-pdFVIII and anti-rFVIII IgG4 were detected, no anti-FVIII IgE was present. The third patient, with moderate HA without inhibitor, atopic, had no anti-FVIII immunoglobulin detected, and allergic symptoms disappeared after switching to rFVIII concentrate. This study corroborates the low incidence of allergic reactions in HA patients. In the three cases presented, the anti-FVIII immunoglobulin profile demonstrated that the allergic manifestation was triggered by other proteins contained in pdFVIII products, and not directed to FVIII.