Efanesoctocog Alfa Prophylaxis for Patients with Severe Hemophilia A.

BACKGROUND: Efanesoctocog alfa provides high sustained factor VIII activity by overcoming the von Willebrand factor-imposed half-life ceiling. The efficacy, safety, and pharmacokinetics of efanesoctocog alfa for prophylaxis and treatment of bleeding episodes in previously treated patients with severe hemophilia A are unclear. METHODS: We conducted a phase 3 study involving patients 12 years of age or older with severe hemophilia A. In group A, patients received once-weekly prophylaxis with efanesoctocog alfa (50 IU per kilogram of body weight) for 52 weeks. In group B, patients received on-demand treatment with efanesoctocog alfa for 26 weeks, followed by once-weekly prophylaxis with efanesoctocog alfa for 26 weeks. The primary end point was the mean annualized bleeding rate in group A; the key secondary end point was an intrapatient comparison of the annualized bleeding rate during prophylaxis in group A with the rate during prestudy factor VIII prophylaxis. Additional end points included treatment of bleeding episodes, safety, pharmacokinetics, and changes in physical health, pain, and joint health. RESULTS: In group A (133 patients), the median annualized bleeding rate was 0 (interquartile range, 0 to 1.04), and the estimated mean annualized bleeding rate was 0.71 (95% confidence interval [CI], 0.52 to 0.97). The mean annualized bleeding rate decreased from 2.96 (95% CI, 2.00 to 4.37) to 0.69 (95% CI, 0.43 to 1.11), a finding that showed superiority over prestudy factor VIII prophylaxis (P<0.001). A total of 26 patients were enrolled in group B. In the overall population, nearly all bleeding episodes (97%) resolved with one injection of efanesoctocog alfa. Weekly prophylaxis with efanesoctocog alfa provided mean factor VIII activity of more than 40 IU per deciliter for the majority of the week and of 15 IU per deciliter at day 7. Prophylaxis with efanesoctocog alfa for 52 weeks (group A) improved physical health (P<0.001), pain intensity (P = 0.03), and joint health (P = 0.01). In the overall study population, efanesoctocog alfa had an acceptable side-effect profile, and the development of inhibitors to factor VIII was not detected. CONCLUSIONS: In patients with severe hemophilia A, once-weekly efanesoctocog alfa provided superior bleeding prevention to prestudy prophylaxis, normal to near-normal factor VIII activity, and improvements in physical health, pain, and joint health. (Funded by Sanofi and Sobi; XTEND-1 ClinicalTrials.gov number, NCT04161495.).

Phase 3 Trial of Concizumab in Hemophilia with Inhibitors.

BACKGROUND: Concizumab is an anti-tissue factor pathway inhibitor monoclonal antibody designed to achieve hemostasis in all hemophilia types, with subcutaneous administration. A previous trial of concizumab (explorer4) established proof of concept in patients with hemophilia A or B with inhibitors. METHODS: We conducted the explorer7 trial to assess the safety and efficacy of concizumab in patients with hemophilia A or B with inhibitors. Patients were randomly assigned in a 1:2 ratio to receive no prophylaxis for at least 24 weeks (group 1) or concizumab prophylaxis for at least 32 weeks (group 2) or were nonrandomly assigned to receive concizumab prophylaxis for at least 24 weeks (groups 3 and 4). After a treatment pause due to nonfatal thromboembolic events in three patients receiving concizumab, including one from the explorer7 trial, concizumab therapy was restarted with a loading dose of 1.0 mg per kilogram of body weight, followed by 0.2 mg per kilogram daily (potentially adjusted on the basis of concizumab plasma concentration as measured at week 4). The primary end-point analysis compared treated spontaneous and traumatic bleeding episodes in group 1 and group 2. Safety, patient-reported outcomes, and pharmacokinetics and pharmacodynamics were also assessed. RESULTS: Of 133 enrolled patients, 19 were randomly assigned to group 1 and 33 to group 2; the remaining 81 were assigned to groups 3 and 4. The estimated mean annualized bleeding rate in group 1 was 11.8 episodes (95% confidence interval [CI], 7.0 to 19.9), as compared with 1.7 episodes (95% CI, 1.0 to 2.9) in group 2 (rate ratio, 0.14 [95% CI, 0.07 to 0.29]; P<0.001). The overall median annualized bleeding rate for patients receiving concizumab (groups 2, 3, and 4) was 0 episodes. No thromboembolic events were reported after concizumab therapy was restarted. The plasma concentrations of concizumab remained stable over time. CONCLUSIONS: Among patients with hemophilia A or B with inhibitors, the annualized bleeding rate was lower with concizumab prophylaxis than with no prophylaxis. (Funded by Novo Nordisk; explorer7 ClinicalTrials.gov number, NCT04083781.).

The effects of emicizumab on in vitro coagulation and fibrinolysis parameters in patients with disseminated intravascular coagulation with and without addition of anti-FVIII antibody.

BACKGROUND: Emicizumab (Emi) is used as haemostatic prophylaxis for patients with haemophilia A (PwHA). Disseminated intravascular coagulation (DIC) is a condition characterized by persistent systemic activation of coagulation, but there is yet no information on coagulation and fibrinolysis potentials in Emi-treated PwHA with DIC. AIM: To examine the effect of Emi on coagulation and fibrinolysis potentials in HA-model DIC plasmas. METHODS: Plasma from a patient with sepsis-DIC (seven patients) was treated with anti-factor (F)VIII monoclonal antibody (HA-model DIC plasma) and incubated with Emi (50 µg/mL). The plasma was then assessed using clot-fibrinolysis waveform analysis (CFWA). Coagulation and fibrinolysis parameters were expressed as ratios relative to normal plasma (|min1|-ratio and |FL-min1|-ratio, respectively). PATIENTS AND RESULTS: In case 1, coagulant potential was slightly high and fibrinolytic potential was extremely low, presenting a coagulant-dominant state (|min1|-ratio/|FL-min1|-ratio: 1.1/.38). In cases 2-5, fibrinolytic potential was not suppressed, but there were marked hypercoagulant potentials, indicating relative coagulant-dominant states. In case 6, coagulant and fibrinolytic potentials were increased but well balanced (|min1|-ratio/|FL-min1|-ratio: 1.38/1.28). In case 7, both potentials were severely deteriorated in not only CFWA but also the thrombin/plasmin generation assay. The addition of Emi into the HA-model DIC plasmas increased |min1|-ratio values in all cases, but the coagulant potentials did not exceed the initial ones (DIC plasma before treatment with anti-FVIII antibody). CONCLUSIONS: The presence of Emi in the HA-model DIC plasma improved coagulation potentials, but did not increase coagulation potentials beyond those of DIC plasma in non-HA states.

Hybrid human-porcine factor VIII proteins partially escape the inhibitory effects of anti-factor VIII inhibitor alloantibodies having A2 or C2 domain specificity.

INTRODUCTION: Porcine factor (pF)VIII has low cross-reactivity with anti-human (h)FVIII inhibitor alloantibodies. Clinical trials of pFVIII in congenital haemophilia A patients with inhibitor (PwHA-I) are in progress. Most polyclonal anti-hFVIII inhibitors recognize its A2 and/or C2 domain(s), and recombinant human-porcine hybrid (hp)FVIII proteins may escape neutralization by these inhibitors. AIM: To evaluate the ability of hpFVIII to limit the anti-FVIII activity of inhibitor alloantibodies. METHODS: Three hybrid proteins were created by substituting the hFVIII A2, C2 domain or both with the corresponding domains of pFVIII [termed hp(A2), hp(C2) and hp(A2/C2), respectively]. The reactivity of these hybrids was assessed by one-stage clotting assays (OSA), thrombin generation assays (TGA) and rotational thromboelastometry (ROTEM) by adding them to FVIII-deficient samples. RESULTS: OSA demonstrated that the hybrid proteins avoided neutralization by anti-FVIII A2 or C2 monoclonal antibodies (mAb) and polyclonal inhibitor-antibodies (polyAb) from PwHA-I. In TGA, thrombin generation with hp(A2) and hp(A2/C2) was not attenuated in the presence of patient IgG recognizing anti-A2 domain. In contrast, that with hFVIII and hp(C2) was suppressed by this IgG to levels equivalent to those of FVIII-deficient plasma. With anti-A2/C2 polyAb, the activity of hp(A2/C2) was unaffected. ROTEM demonstrated that the addition of hp(A2) or hp(A2/C2) to anti-A2 polyAb shortened clot times/clot formation times, whilst hFVIII or hp(C2) were ineffective. Similarly with anti-A2/C2 polyAb, hp(A2/C2) restored coagulation potential to a greater extent than hp(A2) and hp(C2). CONCLUSION: Hybrid FVIII proteins containing porcine FVIII A2 and/or C2 domain(s) could support effective therapy in PwHA-I by avoiding neutralization.

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.

The clinical and genetic landscape of early-onset thrombophilia in Japan.

OBJECTIVES: To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20 years of age were studied in Japan. METHODS/RESULTS: Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n = 55), PS (n = 29), or AT deficiency (n = 18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p = .019). CONCLUSIONS: We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

ROTEM could be useful for lupus anticoagulant hypoprothrombinemia syndrome.

BACKGROUND: Lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS) is a rare disease caused by acquired factor II (FII) deficiency and lupus anticoagulant. Patients with LAHPS typically present with thrombosis and bleeding. However, little information is available on the evaluation of coagulation potential in patients with LAHPS. We examined global coagulation potentials in patients with LAHPS during the clinical course in this study. METHODS: Coagulation potentials in two pediatric patients with LAHPS were assessed by measuring clotting time (CT) and clot formation time using Ca2+-triggered rotational thromboelastometry (ROTEM), CT and maximum coagulation velocity using clot waveform analysis (CWA), and lag time and peak thrombin using the thrombin generation assay (TGA). The day of admission was defined as day 0. RESULTS: In case 1, the bleeding symptoms disappeared by day 5. However, the TGA and CWA results were markedly lower than normal, although FII activity (FII:C) returned to within the normal range by day 14. In contrast, ROTEM revealed a recovery to near-normal levels (day 14). All coagulation parameters (day 80) were within normal ranges. In case 2, coagulation potential was severely depressed until day 12, although FII:C returned to normal levels. Bleeding symptoms disappeared on day 19, and the ROTEM data revealed that the parameters were close to the normal range. The coagulation parameters in all assays were normalized on day 75. CONCLUSIONS: Recovery of coagulation potential in patients with LAHPS was slower than the recovery of FII:C. Moreover, ROTEM appeared to be clinically useful for assessing coagulation potential in patients with LAHPS.

Current and future therapies for haemophilia-Beyond factor replacement therapies.

Some non-factor products that work by facilitating the coagulation pathway (emicizumab) and blocking the anticoagulant pathway (fitusiran, concizumab and marstacimab) for patients with haemophilia (H) have been developed, and clinical trials using these products are currently ongoing. Prophylaxis using non-factor products by subcutaneous administration provides marked reductions of bleeding episodes in patients with HA or HB, regardless of the presence of inhibitor. Emicizumab has already been approved globally. Emicizumab alters the phenotype of patients with HA from severe to mild by maintaining trough levels of equivalent factor VIII activity (15-20 iu/dl). Phase 3 clinical trials and long-term observations assessing emicizumab revealed tolerable safety and efficacy. However, thrombotic events have occurred in patients receiving these non-factor products. Furthermore, monitoring of the haemostatic function of these products with concomitant therapy is also required in clinical practice. These products have promising haemostatic efficiency, but wider clinical experience is needed to provide optimal therapeutic strategies in the future.

Clot Waveform Analysis for Monitoring Hemostasis.

Clot waveform analysis (CWA) is a recently developed global coagulation assessment, based on the continuous observation of changes in light transmittance, absorbance, or light scattering that occurs as fibrin formed in a plasma sample during routine clotting tests such as activated partial thromboplastin time (aPTT) and prothrombin time (PT). CWA can utilize qualitative waveform patterns as well as sensitive quantitative parameters and can be used as a simple method to assess global hemostasis, and can be applied to various challenging clinical situations. Although not all coagulation analyzers currently in use are able to provide CWA, the number of analyzers available to do so is increasing, as the usefulness of this process has become more widely recognized. CWA can be based on the coagulation mechanism of aPTT, an intrinsic trigger, and this has been reported in many studies, including diagnosis and treatment of patients with hemophilia, disseminated intravascular coagulation, and monitoring of anticoagulants and thrombosis. CWA using trace amounts of tissue factors also has the potential to expand the applications of this technology. Recently, there have been reports of the combined evaluation of fibrinolytic dynamics. Among the existing global coagulation assays, CWA may prove to be the easiest to standardize in clinical practice. However, more extensive testing using standardized methods in various clinical settings is needed to determine the true role of CWA in the evaluation of hemostasis and thrombosis in the future.

The in vitro effect of anticoagulant agents on coagulation and fibrinolysis in the presence of emicizumab in the plasmas from patients with haemophilia A.

INTRODUCTION: Emicizumab is used as hemostatic prophylaxis for patients with hemophilia A (PwHA), irrespective of the presence of inhibitors. Although bacterial infection can lead to a procoagulant state, there is limited information on coagulation and fibrinolysis potentials in emicizumab-treated PwHA and on the use of anticoagulants in such cases. AIM: We examined whether anticoagulants affect the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab. METHODS: Plasma from PwHA was in vitro supplemented with emicizumab (50 µg/mL; emi-plasma) and anticoagulants (recombinant thrombomodulin (rTM), nafamostat mesylate (NM), unfractionated heparin (UFH), or low-molecular-weight heparin (LMH)). PwHA plasma spiked with rFVIII (1 IU/mL) was used as a reference (ref-plasma). The coagulation and fibrinolysis potentials in plasma was measured by thrombin and plasmin generation assay (T/P-GA) and clot-fibrinolysis waveform analysis (CFWA). RESULTS: In T/P-GA and CFWA, coagulation potentials (maximum coagulation velocity; |min1|, and peak thrombin; Th-Peak) in plasma rose with increasing concentrations of emicizumab and rFVIII, but fibrinolytic potentials (peak plasmin; Plm-Peak, and maximum fibrinolytic velocity; |FL-min1|) remained unchanged. Adding rTM, NM, and UFH to emi-plasma suppressed coagulation and fibrinolysis potentials, similar to ref-plasma. Regarding the heparin, UFH and LMH inhibited the improved coagulation in emi-plasma. UFH inhibited fibrinolysis as well, but LMH did not. CONCLUSIONS: Anticoagulants could exhibit the inhibitory effects on the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab, similar to those in normal plasma.

Peri-operative hemostatic management of tooth extraction in patients with hemophilia A, with and without inhibitors, receiving emicizumab prophylaxis.

INTRODUCTION: Emicizumab treatment may allow patients with hemophilia A without (PwHA) and with inhibitors (PwHA-I) to undergo some minor surgeries, such as tooth extraction, without peri-operative factor infusions. However, criteria for determining the necessity of factor infusions before minor surgeries are unknown. AIM: We report the peri-operative hemostatic management and outcomes of emicizumab-treated PwHA and PwHA-I cases who underwent tooth extractions using our institutional protocol. METHODS: We retrospectively evaluated PwHA and PwHA-I who underwent tooth extraction with emicizumab prophylaxis at our institution. Local bleeding risk was assessed based on the method, number, and site of tooth extraction. Hemostasis was monitored peri-operatively by rotational thromboelastometry (ROTEM). Hemostatic agents and a mouth splint were used. RESULTS: Twenty-nine extractions (17 interventions) were performed in eight PwHA and two PwHA-I. Based on ROTEM, pre-operative factor infusions were used in ten PwHA and four PwHA-I interventions. Among nine low local bleeding risk interventions, three (33.3%) each received no infusions, one dose of factor infusion pre-operatively, and pre- and post-operative factor infusions. All eight high local bleeding risk interventions involved planned factor infusions. Absorbable hemostats were used in all extractions. A mouth splint was used in 21/25 (84.0%) PwHA and in 4/4 (100%) PwHA-I extractions. No post-extraction bleeding or thrombotic events occurred. CONCLUSIONS: Use of a systemic hemostatic treatment plan according to the local bleeding risk, peri-operative coagulation status assessment using ROTEM, filling the extraction socket with hemostats, and use of a mouth splint can achieve effective and safe hemostatic management in emicizumab-treated PwHA and PwHA-I.

Anti-idiotype monoclonal antibodies against emicizumab enable accurate procoagulant and anticoagulant assays, irrespective of the test base, in the presence of emicizumab.

INTRODUCTION: Emicizumab markedly shortens the activated partial thromboplastin time (aPTT), resulting in inaccurate measurements of procoagulant and anticoagulant factor activities. We have recently reported that mixtures of two different anti-idiotype monoclonal antibodies against emicizumab (anti-emicizumab-mAbs) allow measurement of factor (F)VIII activity (FVIII:C) and FVIII inhibitor in emicizumab-containing plasmas. It is unknown whether anti-emicizumab mAbs can work for other aPTT-based procoagulant and anticoagulant assays. AIM: To investigate whether anti-emicizumab mAbs were measured by all of the aPTT-based assays tested. METHODS: Two anti-emicizumab-mAbs (300 µg/mL each) were preincubated with emicizumab (200 µg/mL)-spiked FVIII-deficient plasma; we then measured FVIII:C, FIX:C, FXI:C, FXII:C, protein (P)C:C, PS:C, global PC-FV (aPTT-based), and prothrombin time (PT), diluted Russel's viper venom time (dRVVT), chromogenic-based FVIII:C, FIX:C and PC:C (non-aPTT-based). Emicizumab (100 µg/mL)-spiked haemophilia (H)A plasmas from patients (n = 23) were also measured. RESULTS: Emicizumab shortened the clotting time in all aPTT-based assays, resulting in high levels of FVIII:C, FIX:C, FXI:C and FXII:C; low levels of PC:C and PS:C; and false-positive results for activated PC resistance. The addition of anti-emicizumab-mAbs to emicizumab-added plasma restored all factors to the initial levels without emicizumab. Chromogenic FVIII:C measurement by human FIXa/FX was affected by emicizumab, but anti-emicizumab mAbs cancelled this effect. PT-based assays and dRVVT, chromogenic FIX:C and PC:C assays showed no effect with emicizumab. Twenty-three plasma samples from HA patients also showed similar patterns. CONCLUSION: Anti-emicizumab mAbs in vitro could cancel the effect of emicizumab, irrespective of the test base, resulting in accurate measurements of procoagulant and anticoagulant factor activity.

Plasma-derived factor VIIa and factor X mixture agent (MC710) prophylaxis in haemophilia B patients with inhibitors.

INTRODUCTION: Haemophilia B patients with factor IX inhibitors have particularly unmet needs for conventional therapy. AIM: Phase II/III clinical trial, multicentre, open-label, prospective, self-controlled study was conducted to assess MC710 prophylaxis in haemophilia B patients with inhibitors. METHODS: We enrolled haemophilia patients who had received episodic or prophylactic treatment with bypassing agents up to that time. The participants continued their conventional therapy for 24 weeks and then MC710 was prophylactically infused intravenously every 2 or 3 days at 60 to 120 µg as FVIIa per kilogram of body weight for 24 weeks. The primary endpoint was the annual bleeding rate (ABR) requiring bypassing agents, which was compared intraindividually between the conventional therapy period and the MC710 prophylaxis period. RESULTS: A total of 11 male haemophilia B patients were enrolled. The median ABR ratio for each participant (the prophylaxis period ABR divided by the conventional therapy period ABR) was .33 (2.1/6.5), range from .00 to 3.77. ABR ratios for 9 of the 11 patients ranged from .00 to .60, and 3 of the 9 patients had zero bleeding events during the prophylaxis period. Meanwhile, ABR ratios for the remaining two patients were 2.53 and 3.77, respectively. Although a fibrinogen decrease recovered by the dose reduction was reported for only one participant as the sole adverse drug reaction in this study, no thrombotic events or other safety concerns were reported. CONCLUSION: MC710 prophylaxis is considered to be decrease the bleeding rate in haemophilia B patients with inhibitors without safety concerns.

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.

Hemostatic potential of recombinant von Willebrand factor and standard or pegylated extended half-life recombinant factor VIII on thrombus formation under high shear flow.

BACKGROUND: Von Willebrand factor (VWF) and factor VIII (FVIII) complex play a pivotal role in hemostasis. A deficiency or defect of VWF causes von Willebrand disease (VWD). Recombinant (r)VWF product has proved to be effective for hemostatic treatment of VWD, but limited information is available on their role in moderating thrombus formation under flow condition. We aimed to assess thrombus formation in the presence of rVWF combined with rFVIII or pegylated-extended half-life rFVIII (peg-EHL-rFVIII) in VWD whole blood under high shear flow. METHODS: Perfusion chamber experiments under high shear (2,500 s- 1) combined with immunostaining were performed using patient's whole blood with type 1 VWD, mixed with rVWF (Vonvendi®; 1.6 IU/mL), rFVIII or peg-EHL-rFVIII (Advate® or Adynovate®; 1.0 IU/mL), or both. Similar experiments were also conducted with clinical medical devices (T-TAS®). RESULTS: The addition of rFVIII did not augment thrombus formation assessed by surface coverage (SC) and thrombus height (TH), whereas rVWF enhanced these parameters (SC 19.1 ± 1.1% vs. 30.1 ± 4.1%, TH 2.2 ± 0.14 µm vs. 3.6 ± 0.40 µm, respectively). The co-presence of rVWF/rFVIII was comparable to plasma-derived VWF/FVIII (Confact®, VWF:FVIII ratio = 1.6:1.0) for increasing thrombogenicity in SC (32.5 ± 4.3% vs. 38.7 ± 5.5%) and in TH (5.0 ± 0.60 µm vs. 5.5 ± 0.64 µm), respectively. The pre-incubation time with rVWF and rFVIII appeared to have a little effect on the size of thrombus. Peg-EHL-rFVIII mediated thrombus formation to similar extent as rFVIII in the co-presence of rVWF. Similar results were obtained even with T-TAS. Immunostaining demonstrated that rFVIII and peg-EHL-rFVIII were similarly co-localized with rVWF in formed thrombi, indicating that pegylation did not interfere with molecular complexes. CONCLUSION: The effects of high-level rVWF and peg-EHL-rFVIII on thrombus formation were comparable to conventional therapeutic products in a patient's whole blood with VWD under high shear flow.

The use of infrared thermography for non-invasive detection of bleeding and musculoskeletal abnormalities in patients with hemophilia: an observational study.

BACKGROUND: In patients with hemophilia (PwH), bleeding often occurs in joints and muscles, and early detection of hemorrhage is important to prevent the onset and progression of mobility impairment. Complex-Image analysis such as ultrasonography, computed tomography, and magnetic resonance imaging are used to detect bleeding. On the other hand, no simple and rapid method to detect the active bleeding has been reported. Local inflammatory responses occur when blood leaks from damaged vessels, and the temperature at the site of active bleeding could be expected to increase in these circumstances, leading to an increase in surrounding skin temperature. Therefore, the purpose of this study was to investigate whether the measurement of skin temperature using infrared thermography (IRT) can be used as a diagnostic aid to detect active bleeding. METHODS: Fifteen PwH (from 6 to 82 years old) complaining of discomfort such as pain were examined. Thermal images were obtained simultaneously at the affected sides and comparable unaffected sides. The average skin temperature of the affected side and of the unaffected side were measured. The temperature differences were calculated by subtracting the average skin temperature at the unaffected side from the affected side. RESULTS: In eleven cases with active bleeding, the skin temperature at the affected side was more than 0.3 °C higher (0.3 °C to 1.4 °C) compared to the unaffected side. In two cases without active bleeding, there were no significant differences in skin temperature between the affected and unaffected sides. In two cases with previous rib or thumb bone fracture, the skin temperature at the affected side was 0.3 °C or 0.4 °C lower than that of the unaffected side, respectively. In two cases with active bleeding in which longitudinal evaluation was conducted, the difference in skin temperature decreased after hemostatic treatment. CONCLUSION: The analysis of skin temperature deference using IRT was a useful supportive tool to readily assess musculoskeletal abnormalities and bleeding in PwH as well as to determine the success of the hemostatic treatment.

The First Case in Japan of Fulminant Myocarditis Due to Multisystem Inflammatory Syndrome in Children (MIS-C) That Required Mechanical Circulatory Support.

Multisystem inflammatory syndrome in children (MIS-C) is a novel hyperinflammatory syndrome that is associated with severe acute respiratory syndrome coronavirus 2 infections. Reports describing the mechanical circulatory support (MCS) and myocardial biopsy for fulminant myocarditis due to MIS-C are limited.A 13-year-old male patient with MIS-C underwent treatment, including immunosuppressive therapy and MCS devices, and managed to recover from pulseless electrical activity cardiac arrest.This is the first patient in Japan with MIS-C who required MCS devices in Japan. Appropriate and immediate treatment with immunosuppressive therapy and MCS devices is important.

[Elucidation of an altered anticoagulant function due to Factor V abnormality and development of a simple screening assay for thrombophilia].

Coagulation factor V (FV) is both procoagulant and anticoagulant functions. Congenital FV abnormality, which are caused by mutations in the FV gene, are characterized by a tendency to bleed. However, FV-R506Q (FVLeiden) is the most common FV abnormality that eliminates an activated protein C (APC) cleavage site, resulting in the occurrence of deep venous thrombosis (DVT). In Japan, the thrombotic predisposition caused by FVLeiden and FV molecular abnormalities was believed to be nonexistent. We did, however, report the first case in Japan of a young patient with FV abnormality-related thrombosis. The recurrent DVT in this case was caused by a novel mutation of FV-W1920R (FVNara), located in the C1 domain and far from the APC cleavage sites. We considered the possibility that there were cases of FV-related thrombotic predisposition that had gone undetected in Japan. We thoroughly examined FV-related anticoagulant function to understand the pathogenesis of thrombosis caused by FV abnormality. Furthermore, using recombinant thrombomodulin, we successfully developed a novel assay with clot waveform analysis for the rapid detection of FV deficiency with APC resistance. Other FV abnormality-related thrombosis has been reported in Japan in recent years, and we hope to further clarify the FV-related thrombotic predisposition in the future.

Emicizumab enhances thrombus formation in vitro under high shear flow conditions in whole blood from patients with type 1 and type 3 von Willebrand disease.

INTRODUCTION: Type 1 and type 3 von Willebrand disease (VWD) are caused by partial and complete, quantitative deficiency of von Willebrand factor (VWF), respectively, and factor (F)VIII/VWF complex concentrates are used for haemostatic treatment. Emicizumab, mimics activated FVIII, reduces bleeding in haemophilia A patients. The effects of emicizumab on haemostasis in both types of VWD remain to be fully established, however. AIM: To examine the effects of emicizumab on thrombogenesis in type 1 and type 3 VWD. PATIENTS/METHODS: Perfusion chamber experiments under high shear conditions (2500 s-1 ) combined with immunostaining were performed using whole blood samples from patients with type 1 (VWF:Ag 25 U/dl) and type 3 VWD (<1.0 U/dl). RESULTS: The addition of FVIII (1 U/ml) to type 1 blood did not affect thrombus formation, whilst supplementation with VWF (1.6 U/ml) or FVIII/VWF (1 U/ml/1.6 U/ml) enhanced thrombogenesis to a similar extent. FVIII/VWF promoted thrombus formation significantly more than VWF alone, however, in type 3 blood. Emicizumab (100 µg/ml) augmented thrombus formation in type 3 blood compared to FVIII, and this potency seemed to be somewhat greater than that of VWF. Surface coverage of formed thrombus in type 3 VWD was less than that in type 1 VWD, but thrombus height was comparable in both. The addition of emicizumab to type 3 blood enhanced thrombin generation and fibrin formation compared to control IgG. CONCLUSION: Emicizumab promoted mechanisms of thrombus formation in vitro in type 3 and type 1 VWD, suggesting the possibility of alternative therapeutic protocols in these patients.

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.