Force-sensing treadmill gait analysis system can detect gait abnormalities in haemophilia patients without arthropathy.

BACKGROUND: Joint damage in patients with haemophilia (PwH) is commonly assessed by imaging, but few reports have described how structural changes in joints, for example, haemophilic arthropathy (HA)-affect gait ability. OBJECTIVES: We evaluated gait function among PwH with HA, PwH without HA, and people without haemophilia (non-PwH) using a Zebris FDM-T treadmill (FDM-T), an easy-to-use gait assessment instrument with a force sensor matrix. METHODS: The following gait parameters were collected: centre of pressure trajectory intersection (COPi) anterior/posterior variability, COPi lateral variability, COPi anterior/posterior symmetry, COPi lateral symmetry, single-limb support line (SLSL) length, and SLSL variability. Participants walked at their typical gait speed. The physical function of the PwH was assessed by the Hemophilia Joint Health Score (HJHS). Parameters were compared among the three groups. RESULTS: Twelve PwH with HA, 28 PwH without HA, and 12 non-PwH were enrolled. Gait speed significantly differed between groups (non-PwH, 3.1 ± 0.7; PwH without HA, 2.0 ± 0.7; PwH with HA; 1.5 ± 0.4). The COPi anterior/posterior variability, COPi lateral variability, SLSL length, and SLSL variability were greater in the PwH groups than in the non-PwH group. The COPi lateral symmetry differed between PwH with HA and the other groups. The HJHS was not correlated with gait parameters among PwH with HA. CONCLUSIONS: Gait parameters and speed were abnormal in both PwH with HA and PwH without HA. The FDM-T can be used to identify early stages of physical dysfunction that cannot be detected by conventional functional assessments such as the HJHS.

Coagulant potentials of emicizumab in the plasmas from infant and toddler patients with hemophilia A.

BACKGROUND: Emicizumab significantly reduces bleedings in patients with hemophilia A (PwHA). A clinical study (HAVEN 7; NCT04431726) for PwHA aged less than or equal to 12 months is ongoing, but emicizumab-driven coagulation potential in PwHA in early childhood remains to be clarified. AIM: To investigate the in vitro or in vivo coagulation potential of emicizumab in plasmas obtained from infant and toddler PwHA. METHODS: Twenty-seven plasma samples from 14 infant/toddler PwHA (aged 0-42 months, median 19 months) who received emicizumab (n = 9), factor (F)VIII products (n = 8), or no treatment (n = 10) were obtained. FVIII activity in FVIII-treated plasmas was cancelled by the addition of anti-FVIII monoclonal antibody (mAb). Emicizumab-treated plasmas (in vivo) and emicizumab-spiked plasmas (in vitro) were analyzed. Emicizumab-untreated plasma or emicizumab-treated plasma supplemented with two anti-emicizumab mAbs were used as references. Adjusted maximum coagulation velocity (Ad|min1|) by clot waveform analysis and peak thrombin (Peak-Th) by thrombin generation assay was assessed. RESULTS: Ad|min1| values in 24 samples were improved by the presence of emicizumab. Values did not improve in the three remaining samples (aged 1, 23, and 31 months). Although the presence of emicizumab showed an age-dependent increase in Peak-Th in 20 samples, this increase was not observed in seven samples (aged 0, 1, 1, 2, 8, 19, and 36 months). Emicizumab-dependent increases in both Ad|min1| and Peak-Th were shown in 18 samples, and increases in either parameter were shown in eight samples. One sample (from patient aged 1 month) showed no increase in both, however. CONCLUSION: Emicizumab could improve coagulant potential in plasmas from infant/toddler patients with hemophilia A.

Clinical conditions and risk factors for inhibitor-development in patients with haemophilia: A decade-long prospective cohort study in Japan, J-HIS2 (Japan Hemophilia Inhibitor Study 2).

BACKGROUND: Inhibitor-development is a serious complication in patients with haemophilia (PwH). Previous studies reported that therapeutic and genetic factors could be associated with these alloantibodies. Relevant clinical features such as genetic-background and different treatment regimens in Japan remain unclear, however. AIMS: To analyse a nation-wide Japanese registry for PwH, and to examine risk factors for inhibitor-development. METHODS AND RESULTS: Newly diagnosed patients with haemophilia A (PwHA) or haemophilia B (PwHB) without inhibitors after 2007, and with treatment records traceable from 0 to 75 exposure days (ED), were enrolled in the Japan Hemophilia Inhibitor Study 2 (J-HIS2) initiated in 2008. Of 417 patients (340 PwHA, 77 PwHB) from 46 facilities, 83 (76 PwHA, 7 PwHB) were recorded with inhibitors by July 2020. Inhibitors were observed in 31.0% of severe PwHA, 8.0% moderate and 1.6% mild and in 17.1% of severe PwHB. The majority of inhibitors (89.7% in severe PwHA and 71.4% in severe PwHB) were detected on or before 25ED (median 12ED in PwHA and 19ED in PwHB). Genotyping in these severe patients identified an association between inhibitor-development and null variants of F8 (P < .01) or F9 (P < .05). A lower incidence of inhibitors was recorded in severe PwHA treated with prophylaxis than in those treated on-demand (P < .01). A past-history of intracranial-haemorrhage appeared to be associated with inhibitor-development, while FVIII-concentrates infusion and routine vaccination on the same day was not related to inhibitor-development. CONCLUSION: The J-HIS2 study has identified significant clinical variables associated with inhibitor-development in Japanese PwH, consistent with other global studies.

Novel Insights and New Developments Regarding Coagulation Revealed by Studies of the Anti-Factor IXa (Activated Factor IX)/Factor X Bispecific Antibody, Emicizumab.

Emicizumab is a humanized anti-FIXa/FX (factor IXa/X) bispecific monoclonal antibody that mimics FVIIIa (activated factor VIII) cofactor function. The hemostatic efficacy of emicizumab has been confirmed in clinical studies of patients with hemophilia A, irrespective of the presence of FVIII inhibitors. Emicizumab differs in some properties from FVIIIa molecule. Emicizumab requires no activation by thrombin and is not inactivated by activated protein C, but emicizumab-mediated coagulation is regulatable and maintains hemostasis. A small amount of FIXa (activated factor IX) is required to initiate emicizumab-mediated hemostasis, whereas tissue factor/FVIIa (activated factor VII)-mediated FXa (activated factor X) and thrombin activation initiates FVIIIa-mediated hemostasis. Fibrin formation, followed by fibrinolysis, appears to be similar between emicizumab- and FVIIIa-mediated hemostasis. These results suggest possible future uses of emicizumab for treating hemorrhagic diseases other than hemophilia A and reveal previously unobservable behaviors of procoagulation and anticoagulation factors in conventional hemostasis. Here, we have reviewed novel insights and new developments regarding coagulation highlighted by emicizumab.

A microchip flow-chamber assay screens congenital primary hemostasis disorders.

BACKGROUND: Von Willebrand disease (VWD) and platelet function disorders (PFDs) are congenital bleeding disorders caused by primary hemostasis defects. Platelet function tests are time-consuming and require considerable amounts of blood sample, and there have been no easy-to-use assays for assessing platelet function quickly and sensitively. We report the usefulness of a microchip flow-chamber system (T-TAS® ) for detecting and/or predicting clinical severity in patients with VWD type 1 and type 2N and platelet storage pool disease. Here, we developed an application of a screening assay for primary hemostasis disorders. METHODS: Microchips coated with collagen (PL-chip) and collagen/thromboplastin (AR-chip) were utilized to evaluate platelet thrombus formation (PTF) at high shear and fibrin-rich PTF at low shear, respectively, in whole blood samples from 22 patients with VWD (16 type 2A, four type 2B, two type 3) and four patients with PFDs (two BSS, two Glanzmann thrombasthenia). The time-to-increase by 10 kPa (T10 ) was calculated from flow pressure curves. Also, whole blood-induced platelet aggregation was assessed using Multiplate® analysis. RESULTS: PL-chip T10 values ≥10 min successfully distinguished patients with all types of VWD and PFDs from healthy controls, irrespective of age, bleeding scores, and von Willebrand factor levels. However, AR-chip assay incompletely distinguished between type 2A patients and healthy ones. Multiplate analysis permitted screening of PFDs and type 3 VWD, but values in type 2A partially overlapped with those in controls. PL-chip assay did not reflect the clinical severity in these patients. CONCLUSIONS: T-TAS with PL-chip could be a quick screening tool for congenital primary hemostasis disorder, VWD, and PFDs.

[Risk factors of inhibitor development among hemophilia patients revealed in a 10-year prospective cohort study in Japan, J-HIS2 (Japan Hemophilia Inhibitor Study 2)].

The development of an inhibitor is a serious complication for patients with hemophilia (PwH). Previous international studies have reported some therapeutic and genetic factors associated with inhibitor development. However, actual situations, such as genetic-background, treatment, and inhibitor development, have remained unclear in PwH in Japan. The Japan Hemophilia Inhibitor Study 2 (J-HIS2) was organized in 2008 to establish a nation-wide registry system for PwH in Japan and prospectively investigate the risk factors for inhibitor development. Patients who were newly diagnosed after 2007 without inhibitor and whose treatment was traceable from 0 to 75 exposure days were enrolled in J-HIS2. Of the 386 patients (hemophilia A [HA]: 315, hemophilia B [HB]: 71) from 46 facilities, inhibitor development was observed in 77 (HA: 71, HB: 6) by November 2018. Inhibitor development was observed in 31.6% of patients with severe hemophilia A, 6.5% with moderate hemophilia A, and 1.8% with mild hemophilia A. However, it was observed in 15.4% of those with severe hemophilia B. The relative-risk of the F8 null genotype for inhibitor development was higher than that of the non-null one (p<0.01). In patients with severe hemophilia A with 25 exposure days of infusions or inhibitor development, prophylaxis was more protective for inhibitor development than non-prophylaxis (p<0.01). A simultaneous infusion of FVIII-concentrates and vaccination seemed to exert a limited effect on inhibitor development. History of intracranial hemorrhage appears to be associated with inhibitor development.

Assessment of self-/parent-reported quality of life in Japanese children with haemophilia using the Japanese version of KIDSCREEN-52.

INTRODUCTION: Assessing health-related quality of life (HRQOL) is critical for providing comprehensive clinical care to patients with haemophilia. HRQOL in individuals with similar cultural backgrounds should be compared using internationally standardized, generic questionnaires. AIM: To evaluate self-/parent-assessed HRQOL in Japanese children and adolescents with haemophilia A or B. METHODS: Children and adolescents aged 8-18 years were enrolled. The haemophilia group comprised families with haemophilia, and the control group comprised those without chronic illness. HRQOL was assessed using the self-/parent-reported questionnaire KIDSCREEN-52, the Japanese version. The Oslo 3-Item Social Support Scale was investigated. RESULTS: The questionnaire was completed by 36 families in the haemophilia group and 160 parents and children in the control group. Haemophilia children aged 8-12 years had lower scores for 'moods and emotions' than control children; the parents had lower scores in the haemophilia group than in the control group for 'moods and emotions', 'social support and peers', and 'school environment'. No significant differences in HRQOL were observed between both groups of adolescents aged 13-18 years or their parents. Neck-shoulder pain was associated with a low psychological state, including 'self-perception', but other joint pains did not affect the outcomes of the HRQOL indices. Social support weaknesses were associated with low physical and psychological states, whereas unexpected hospital visits identified low values for 'self-perception', 'autonomy', and 'school environment'. CONCLUSION: Proactive mental and clinical care in haemophilia families, especially with young children, will foster a better environment for patients and their parents and ease concerns about progress in haemophilia.

Whole blood ristocetin-induced platelet impedance aggregometry does not reflect clinical severity in patients with type 1 von Willebrand disease.

BACKGROUND: The haemorrhagic phenotype in patients with von Willebrand disease (VWD) is heterogeneous, and assays of von Willebrand factor ristocetin cofactor activity (VWF:RCo) do not always reflect clinical severity, especially in those individuals classed as type 1 VWD. Recent studies have shown that whole blood ristocetin-induced platelet agglutination (WB-RIPA) using an easy-to-use analyzer, Multiplate® platelet impedance technique, could be informative as a diagnostic test in VWD, although inconsistencies were evident in patients with the type 1 disorder, possibly associated with clinical symptoms. AIM: To investigate the relationship between WB-RIPA, bleeding scores (BS) and VWF-related measurements in type 1 VWD. METHODS: WB-RIPA assay using the Multiplate® was performed using whole blood from 55 patients with type 1 VWD. BS was determined using a standardized questionnaire. RESULTS: WB-RIPA values were significantly lower in type 1 VWD than in healthy controls (P < 0.0001). Weak correlations were apparent between WB-RIPA and VWF:RCo or VWF antigen (VWF:Ag; r = 0.22 or 0.28, respectively). There were significant differences in VWF:RCo (P = 0.036) and VWF:Ag (P = 0.0013) between patients with BS ≥4 (defined as abnormal bleeding tendency) and BS <4 (defined as no abnormal bleeding tendency), respectively. However, no significant difference was observed in WB-RIPA between the BS ≥4 group and BS <4 group. Overall, VWD patients with a WB-RIPA level >70 U did not seem to have an abnormal bleeding tendency, but low levels of WB-RIPA did not correlate with BS. CONCLUSION: WB-RIPA did not reflect clinical severity in type 1 VWD patients.

Emicizumab-mediated haemostatic function in patients with haemophilia A is down-regulated by activated protein C through inactivation of activated factor V.

Activated protein C (APC) inactivates activated factor V (FVa) and moderates FVIIIa by restricting FV cofactor function. Emicizumab is a humanized anti-FIXa/FX bispecific monoclonal antibody that mimicks FVIIIa cofactor function. In recent clinical trials in haemophilia A patients, once-weekly subcutaneous administration of emicizumab was remarkably effective in preventing bleeding events, but the mechanisms controlling the regulation of emicizumab-mediated haemostasis remain to be explored. We investigated the role of APC-mediated reactions in these circumstances. APC dose-dependently depressed thrombin generation (TG) initiated by emicizumab in FVIII-deficient plasmas, and in normal plasmas preincubated with an anti-FVIII antibody (FVIII-depleted). FVIIIa-independent FXa generation with emicizumab was not affected by the presence of APC, protein S and FV. The results suggested that APC-induced down-regulation of emicizumab-dependent TG was accomplished by direct inactivation of FVa. The addition of APC to emicizumab mixed with FVIII-depleted FV-deficient plasma in the presence of various concentrations of exogenous FV demonstrated similar attenuation of TG, irrespective of specific FV concentrations. Emicizumab-related TG in FVIII-depleted FVLeiden plasma was decreased by APC more than that observed with native FVLeiden plasma. The findings indicated that emicizumab-driven haemostasis was down regulated by APC-mediated FVa inactivation in plasma from haemophilia A patients without or with FV defects.

Factor (F)VIII/VIIa enhances global haemostatic function in the co-presence of bypassing agents and FVIII among patients with haemophilia A with inhibitor.

Bypassing therapy is essential for the haemostatic management of patients with haemophilia A with inhibitor (PWHA-inh), but the therapeutic effects are inconsistent. We previously reported that activated prothrombin complex concentrates (aPCC) activated factor (F)VIIIin vitro, and was mediated mainly by the activated FVII (FVIIa) contained in aPCC. We have extended those studies to assess global coagulation in whole blood from 18 PWHA-inh in the co-presence of aPCC and FVIII using Ca2+ -triggered rotational thromboelastometry. The clot times (CTs) in the presence of both aPCC (0·05 iu/ml) and recombinant (r)FVIII (1 iu/ml) ex vivo were shortened compared to the aPCC alone (P < 0·01). These enhancing effects of rFVIII were observed, irrespective of recognizing inhibitor epitopes; however, the clot formation time and 'α'-angle were not significantly different. In samples from 7 PWHA-inh post-infusion of aPCC (70-80 iu/kg), only the CTs were shortened in the presence of rFVIIIex vivo compared to its absence (P < 0·05), indicating that the enhanced activity centred on the initiation phase of coagulation. Furthermore, experiments in the co-presence of rFVIIa and rFVIII demonstrated that FVIII accelerated only the CTs. We concluded that FVIII/FVIIa-related coagulation mechanism enhanced global haemostatic function by the co-presence of bypassing agents and FVIII in PWHA-inh.

Reduced plasma factor X is associated with a lack of response to recombinant activated factor VII in patients with hemophilia A and inhibitor, but does not impair emicizumab-driven hemostasis in vitro.

BACKGROUND: The hemostatic effect of recombinant (r) factor (F)VIIa after repetitive intermittent administration may be attenuated in patients with hemophilia A (PwHA) with inhibitors (PwHAwI) creating a clinically unresponsive status, although mechanism(s) remain to be clarified. In patients receiving prophylaxis treatment with emicizumab, concomitant rFVIIa is sometimes utilized in multiple doses for surgical procedures or breakthrough bleeding. AIM AND METHODS: We identified 'unresponsiveness' to rFVIIa, based on global coagulation function monitored using rotational thromboelastometry (ROTEM) in 11 PwHAwI and 5 patients with acquired HA, and investigated possible mechanisms focusing on the association between plasma FX levels and rFVIIa-mediated interactions. RESULTS: Our data demonstrated that FX antigen levels were lower in the rFVIIa-unresponsive group than in the rFVIIa-responsive group (0.46 ± 0.14 IU/mL vs. 0.87 ± 0.15 IU/mL, p < 0.01). This relationship was further examined by thrombin generation assays using a FX-deficient PwHAwI plasma model. The addition of FX with rFVIIa was associated with increased peak thrombin (PeakTh) generation. At low levels of FX (<0.5 IU/mL), rFVIIa failed to increase PeakTh to the normal range, consistent with clinical rFVIIa-unresponsiveness. In the presence of emicizumab (50 µg/mL), PeakTh was increased maximally to 80 % of normal, even at low levels of FX (0.28 IU/mL). CONCLUSIONS: Unresponsiveness to rFVIIa was associated with reduced levels of FX in PwHAwI. Emicizumab exhibited in vitro coagulation potential in the presence of FX at concentrations that appeared to limit the clinical response to rFVIIa therapy.

Emicizumab-mediated hemostatic function assessed by thrombin generation assay in an in vitro model of factor VIII-depleted thrombophilia plasma.

Patients with hemophilia A (PwHA) may have concurrent deficiency of representative anticoagulant proteins, protein (P)C, PS, and antithrombin (AT), which reduces bleeding frequency. However, emicizumab-driven hemostasis in PwHA with such thrombophilic potential remains unclarified. This study investigated the influence of natural anticoagulants on emicizumab-driven coagulation in HA model plasma. Various concentrations of PS and AT were added to PS-deficient plasma and AT-deficient plasma in the presence of anti-FVIII antibody (FVIIIAb; 10BU/mL). PC-deficient plasma was mixed with normal plasma at various concentrations in the presence of FVIIIAb. Emicizumab (50 µg/mL) was added to these thrombophilic HA model plasmas, prior to tissue factor/ellagic acid-triggered thrombin generation assays. Co-presence of emicizumab increased peak thrombin values (PeakTh) dependent on PS, AT, and PC concentrations. Maximum coagulation potentials in the PS-reduced HA model plasmas remained normal in the presence of emicizumab. PeakTh were close to normal in the presence of 50%AT irrespective of emicizumab, but were higher than normal in the presence of 25%AT. Addition of recombinant FVIIa (corresponding to an administered dose of 90 µg/kg) enhanced coagulation potential to normal levels. Our findings provide novel information on hemostatic regulation in emicizumab-treated PwHA with a possible thrombophilic disposition.

Different factor VIII neutralizing effects on anti-factor VIII inhibitor antibodies associated with epitope specificity and von Willebrand factor.

Inhibitor neutralization therapy based on factor (F)VIII replacement is used for haemostatic treatment in haemophilia A patients with inhibitors on low responder, but effects appear to depend on various properties of inhibitors. We investigated this nature by evaluating the global coagulation function in timed-reactions after mixing FVIII (1 U/ml) with anti-FVIII alloantibodies containing distinct epitopes (2·5 Bethesda units/ml). Thrombin generation assays showed that peak thrombin and mean velocity to peak thrombin were depressed by anti-C2 type 1 inhibitors to significantly greater extents than by anti-A2 type 1 and anti-C2 type 2 (2- to 6-fold and 10- to 20-fold, respectively). In the presence of FVIII-von Willebrand Factor (VWF) complex, the anti-C2 type 1-mediated decreased thrombin generation was reduced by 20-40%, reflecting the protective function of VWF. However, the activities of anti-A2 type 1 were little affected, and that of anti-C2 type 2 was rather enhanced by c. 2·5-fold, relative to FVIII. Clot waveform analysis also showed similar patterns. Anti-FVIII monoclonal antibodies with well-defined characteristics demonstrated similar reactions to those with polyclonal inhibitors. In conclusion, the neutralizing effects of FVIII(-VWF) depending on epitopes could have significant therapeutic implications, and it could be important to determine inhibitor properties in order to predict the effects of infused FVIII in neutralization therapy.

Decrease in in vivo coagulant potential of emicizumab in a patient with hemophilia A and inhibitor complicated with infectious mononucleosis.

Emicizumab prophylaxis significantly reduces bleeding episodes in patients with hemophilia A (PwHA). There is little information on coagulant potentials in emicizumab-treated PwHA with infection, however. We encountered an emicizumab-treated PwHA with inhibitor, complicated with Epstein-Barr virus-associated infectious mononucleosis (IM) in phase 1/2 study (ACE001JP/ACE002JP). Although it was a typical clinical course of IM, activated partial thromboplastin time was mildly prolonged but rotational thromboelastometry revealed severely impaired coagulant potential. The blood concentration of emicizumab decreased moderately in the low concentration range, resulting in an increased risk of bleeding and possibly leading to severe ileocecal bleeds requiring coil embolization. The blood concentrations of factors IX/X little decreased and antiemicizumab antibodies did not develop, however. After the influence by IM resolved, his coagulant potentials gradually recovered with the recovery of emicizumab concentration, and parameters by global coagulation assays improved. An IM case for emicizumab-treated PwHA may need to monitor using global coagulation assays.

Longitudinal dynamic changes in factor VIII inhibitor titers in patients with hemophilia A and inhibitors receiving emicizumab prophylaxis.

Emicizumab prophylaxis dramatically reduces bleeding events in patients with hemophilia A (PwHA) with or without factor VIII (FVIII) inhibitors. However, long-term dynamic changes in FVIII inhibitor titers during emicizumab prophylaxis remain to be investigated. We conducted a retrospective follow-up study of FVIII inhibitor titers after initiation of emicizumab prophylaxis in 25 PwHA carrying current or historical FVIII inhibitors. Nineteen PwHA had FVIII inhibitors at initiation of emicizumab prophylaxis (age: median 22 [range 4-60] years and inhibitor titer: 30 [1.0-1450] BU/mL). In 17 of the 19 patients, the inhibitor titers markedly decreased to a median of 1.2 (< 0.6-58) BU/mL at a median follow-up of 71 (38-111) months. In two patients, titers were slightly elevated after initiation of emicizumab but decreased in the long term. The remaining six patients had negative inhibitor status (< 0.6 BU/mL) when switched to emicizumab from FVIII prophylaxis. Five patients maintained negative titers. One patient had inhibitor recurrence, with a peak titer of 1.6 BU/mL that decreased to 0.9 BU/mL. In most cases, FVIII inhibitor titers can be expected to decrease spontaneously during emicizumab prophylaxis, but regular follow-up is necessary to manage breakthrough bleeds.

Comparisons of global coagulation potential and bleeding episodes in emicizumab-treated hemophilia A patients and mild hemophilia A patients.

Emicizumab reduces bleeding events in patients with severe hemophilia A (HA). The coagulation potential of emicizumab at a clinical dose appears to correspond to about 15 IU/dL of factor VIII activity (FVIII:C), the equivalent of converting from a severe to mild phenotype. However, the clinical and laboratory characteristics of HA patients receiving emicizumab (Emi-PwHA) compared with patients with mild HA (PwMHA) remain to be determined. We reviewed clinical data from Emi-PwHA (n = 63) and PwMHA (n = 15) and evaluated comprehensive coagulation function using Ca2+-triggered rotational thromboelastometry (ROTEM) and ellagic acid/tissue factor-triggered clot waveform analysis (modified CWA). The median FVIII:C in PwMHA was 13.0 (IQR 8.5-17.0) IU/dL. Bleeding patterns in both groups were similar and classified into three categories: (1) spontaneous bleeding, post-traumatic, (2) bleeding within 1-2 days, and (3) delayed bleeding after 1-2 weeks. The coagulation potential in Emi-PwHA with and without breakthrough bleeds was comparable. Furthermore, coagulation function in Emi-PwHA was equivalent to PwMHA, although time between treatment and hospitalization for breakthrough bleeds in PwMHA appeared to be longer than those in Emi-PwHA. The coagulation potential and bleeding patterns appeared to be similar in Emi-PwHA and PwMHA, indicating that emicizumab-driven coagulation potential reflected mild HA.

Comprehensive blood coagulation potential in patients with acquired hemophilia A: retrospective analyses of plasma samples obtained from nationwide centers across Japan.

Global coagulation potential was assessed in 59 patients with acquired hemophilia A (PwAHA) by clot waveform analysis (CWA) and/or thrombin and plasmin generation assay. Relationships between factor VIII activity (FVIII:C) and the parameters from CWA and T/P-GA in patients with congenital HA were compared by grading coagulation potential related to FVIII:C: T1 (FVIII:C < 1 IU/dL), T2 (1 ≤ , ≤ 5 IU/dL), T3 (5 < , 12 ≤ IU/dL), and T4 (12 < , ≤ 50 IU/dL). The median FVIII:C and inhibitor titers in PwAHA on admission were 3.3 IU/dL and 63.0 BU/mL, respectively, but global coagulation parameters corresponded to T1 or less. Median FVIII:C levels during follow-up in PwAHA were 1.7-9.6-6.7-40.0-21.7 IU/dL on days 0-14-28-56-93, respectively. CWA-based data corresponded to less than T2 until day 28, but more closely reflected FVIII:C after day 56. Peak thrombin was severely low (near T1) until day 28 and improved modestly after day 56 but remained less than T2. Peak plasmin was lower than T1 until day 56, and returned to T4 on day 93. In conclusion, global coagulation function in PwAHA was impaired to a greater extent than could be anticipated from assays of FVIII:C, until approximately 1 month after immunosuppression and treatment with FVIII-bypassing agents.

The seroprevalence of neutralizing antibodies against the adeno-associated virus capsids in Japanese hemophiliacs.

Adeno-associated virus (AAV) vectors are promising modalities of gene therapy to address unmet medical needs. However, anti-AAV neutralizing antibodies (NAbs) hamper the vector-mediated therapeutic effect. Therefore, NAb prevalence in the target population is vital in designing clinical trials with AAV vectors. Hence, updating the seroprevalence of anti-AAV NAbs, herein we analyzed sera from 100 healthy individuals and 216 hemophiliacs in Japan. In both groups, the overall seroprevalence against various AAV serotypes was 20%-30%, and the ratio of the NAb-positive population increased with age. The seroprevalence did not differ between healthy participants and hemophiliacs and was not biased by the concomitant blood-borne viral infections. The high neutralizing activity, which strongly inhibits the transduction with all serotypes in vitro, was mostly found in people in their 60s or of older age. The multivariate analysis suggested that "60s or older age" was the only independent factor related to the high titer of NAbs. Conversely, a large proportion of younger hemophiliacs was seronegative, rendering them eligible for AAV-mediated gene therapy in Japan. Compared with our previous study, the peak of seroprevalences has shifted to older populations, indicating that natural AAV exposure in the elderly occurred in their youth but not during the last decade.

Correlations between global clotting function tests, duration of operation, and postoperative chest tube drainage in pediatric cardiac surgery.

BACKGROUND: Systemic coagulation disorders after cardiac surgery represent serious postoperative complications. There have been few reports, however, identifying preoperative coagulation tests that predict postoperative bleeding. The aim of the present study was to investigate the relationship between postoperative hemorrhage and coagulation parameters determined by global coagulation assays, to define potential predictive markers. METHODS: Twenty-one pediatric patients were enrolled. Blood samples were collected before and 24 h after cardiac surgery. Laboratory investigations included platelet count, hematocrit, classical coagulation tests [prothrombin time, activated partial thromboplastin time, thrombin-antithrombin complex (TAT)], rotation thromboelastometry (ROTEM), and the thrombin generation test (TGT). The duration of the surgical procedure was recorded. Chest tube drainage was monitored for 24 h after operation as an index of postoperative hemorrhage. RESULTS: Comparisons between preoperative and postoperative results indicated that TAT increased significantly after operation, whereas ROTEM parameters did not show a hypercoagulable pattern. Preoperative endogenous thrombin potential (ETP) measured in the TGT and clot formation time (CFT) in the ROTEM correlated with chest tube drainage. The classical coagulation tests were not informative. Postoperatively, peak height and ETP in TGT, all ROTEM parameters, and duration of surgery were correlated with chest tube drainage. Duration of surgery was correlated with postoperative ROTEM parameters but not with TGT. Postoperative maximum clot firmness and AUC were correlated with platelet count decrease ratio. CONCLUSIONS: The preoperative CFT and ETP provide useful indices for predicting postoperative chest tube drainage volume. In addition, the duration of surgery also correlated with chest tube drainage and affected ROTEM parameters.