Thermolability of factor VIII in donor fresh frozen blood plasma

A criterion of the quality of fresh frozen blood plasma (FFP) is the activity of clotting factor VIII (FVIII).Aim — to identify technological barriers in the study of FVIII thermolability and to describe the requirements for experiments, providing new knowledge about the thermolability of this factor.Basic information. An analysis of domestic and foreign publications devoted to the study of the mechanisms responsible for reducing the value of FVIII activity in donor blood plasma from the moment of donation to the moment of transfusion was carried out. Data on the decrease in FVIII activity at various stages of work with blood plasma are presented. An analysis of methods for preparing samples for studying changes in the values of FVIII in donor blood plasma was performed. The existence of contradictory conclusions about the infl uence on the change in FVIII at the thawing stage of various values of the effects on FFP and poor knowledge of the change in the indicator at the stage of heating to the transfusion temperature after the end of the phase transition in the samples was established. The fundamental differences in the methods of preparing and conducting experiments in previous works are determined. Methods for increasing the reliability of experimental results for studying the thermal lability of FVIII are proposed.

Efanesoctocog alfa for hemophilia A: results from a phase 1 repeat-dose study

Efanesoctocog alfa (rFVIIIFc-VWF-XTEN, BIVV001) is a new class of factor VIII (FVIII) replacement that breaks the von Willebrand factor-imposed FVIII half-life ceiling. In a Phase 1/2a study, single-dose efanesoctocog alfa was well tolerated and no safety concerns were identified. We evaluated the safety, tolerability, and pharmacokinetics of repeat-dose efanesoctocog alfa in a Phase 1 study in previously treated adults (≥150 exposure days) with severe hemophilia A. Participants received four once-weekly efanesoctocog alfa doses (Cohort 1, 50 IU/kg; Cohort 2, 65 IU/kg). All enrolled participants (Cohort 1, n=10; Cohort 2, n=14) completed the study. Inhibitor development to FVIII was not detected. After the last efanesoctocog alfa dose, geometric mean (range) FVIII activity half-life, area under the activity-time curve, and steady state maximum concentration for Cohort 1 and Cohort 2 were 41.3 (34.2-50.1) hours and 37.3 (28.9-43.8) hours, 8290 (5810-10,300) h × IU/dL and 11,200 (7040-15,800) h × IU/dL, and 131 (96-191) IU/dL and 171 (118-211) IU/dL, respectively. There was minimal accumulation after 4 doses. Mean FVIII activity on Day 3 post dose was 46% and 69% and on Day 7 was 10% and 12% for Cohorts 1 and 2, respectively. Overall, four once-weekly doses of efanesoctocog alfa were well tolerated, no safety concerns identified, and no bleeds reported during the treatment period. Once-weekly efanesoctocog alfa provided high sustained FVIII activity within the normal to near-normal range for 3-4 days post-dose and may improve protection against bleeds in patients with hemophilia A. (EU Clinical Trials Register study 2018-001535-51)

Pharmacokinetics-Guided Perioperative Replacement Therapy in Hemophilia a Patients

Purpose: Pharmacokinetics(PK)-based prophylactic treatment has been proven to meet the pharmacoeconomics needs of patients with hemophilia to the greatest extent in recent years，but the way and significance of PK-guided perioperative replacement therapy remain unclear. Methods :In this study, PK parameters (calculated by DAS software), including half-life and in vivo recovery(IVR), were used to guide individualized replacement therapy for surgical patients with hemophilia A. PK profiles were described by a two-compartment model. The collection of perioperative factor VIII(FVIII) plasma concentrations, factor consumption, and blood loss data was used to verify the efficacy of individualized programs. Results :A total of 46 patients underwent 50 surgeries (median age: 32 years, median weight: 60.5 kg), all of which were major surgeries. The median half-life was 15.44h, and the median IVR was 2.29IU dl -1/IU kg -1. In total, 50 surgeries contributed with 528 plasma FVIII activity observations, of which 310 (58.71%) entered the target range. The median intraoperative blood loss of 43 surgeries was 446.9ml. No severe complications occurred during the perioperative period. Hematomas appeared after six surgeries, which have been resolved after treatment at discharge. Inhibitor developed in one patient and was transient. The median consumption of FⅧ concentrates during the perioperative period was 511.7U/kg, which reduced by 26.69% compared with the dosage based on weight (648.3U/kg, P＜0.001). During the perioperative period, the actual factor consumption was consistent with the PK-guided plan (P>0.05). In addition, a negative correlation was found between intraoperative blood loss and immediate postoperative FVIII activity (r= -0.477, P=0.001). Conclusion: PK-guided perioperative replacement therapy in hemophilia A patients can safely and effectively reduce the consumption of FⅧ concentrates. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Rituximab Monotherapy Is Effective for Inhibitor Eradication with Concomitant Porcine Factor VIII Followed By Emicizumab for Bleed Control in Acquired Hemophilia a

Introduction Acquired hemophilia A (AHA) is a rare bleeding disorder in which acquired auto-antibodies to endogenous Factor VIII (FVIII) resulting in decreased FVIII activity. AHA can lead to life-threatening bleeding, with effective treatment requiring both immunosuppressive therapy (IST) and bypassing agents such as recombinant activated Factor VII (rFVIIa) or activated prothrombin complex concentrates (APCC) (Tiede et al. Haematologica 2020). Some, including our group, have begun using emicizumab as well (Knoebl et al. Blood 2020). IST is required for inhibitor eradication, but regimens are heterogenous and have not been systematically compared in the literature. While there is no standard of care IST in these patients, most patients in the literature receive multiple agents, including corticosteroids, mycophenolate mofetil, cyclosporine, and/or rituximab in combination. We report in a prospective cohort that for IST, rituximab monotherapy is an effective strategy. An updated treatment algorithm is offered that has been effective for treatment of these patients at our institution, which adds emicizumab therapy after initial bleed control. Methods We analyzed clinical, pharmacy, and laboratory data from 24 patients treated with rpFVIII at the University of North Carolina for AHA from July 2015 to June 2021. All patients were initially treated according to our previously established dosing algorithm with recombinant porcine FVIII, and the last five patients have received emicizumab after initial factor dosing (see Figure 1). 17 of the patients who received rituximab and were followed at our center subsequently attained inhibitor eradication, six of those received only rituximab therapy. Investigational review board approval was obtained for our data collection and analysis. Patients who did not receive rituximab, failed to reach an inhibitor level <0.5 BU, or who were lost to follow up were excluded from the analysis. For patients that fit the inclusion criteria, the time between date of the first rituximab infusion and the date of inhibitor eradication was calculated. Results All patients in our cohort who we followed until inhibitor eradication (17 of 24 patients) had eradication of inhibitors after a median of 143 days from initiation of immunosuppression. For patients treated with rituximab monotherapy for inhibitor eradication (6 of 17), this goal was reached in a median of 134.5 days (range 76-191 days). For those who received agents in addition to rituximab and have reached inhibitor eradication to date (9 of 17 patients), median days from initiation of immunosuppression to inhibitor eradication was 137.5 days (range 11-485) (P = 0.43 on Mann-Whitney test). Patients were treated as previously reported by our group per an algorithm that starts recombinant porcine FVIII without waiting for a porcine inhibitor and at lower than FDA recommended dosing. Subsequent doses for bleed control are titrated according to one-stage, clot based FVIII activity. This report also includes 5 new patients who, after initial bleed control per our algorithm, were initiated on emicizumab while awaiting inhibitor eradication. There was no correlation between time to rituximab initiation and time to inhibitor eradication in both those who received rituximab monotherapy and those who had multiple IST agents. There was also no significant difference in initial inhibitor titer between groups with median initial inhibitor titer of 104 BU in the rituximab monotherapy group, and 70 BU in the multiple IST agents group (see Figure 3). Conclusions Rituximab monotherapy appears to be an effective strategy for inhibitor eradication in acquired hemophilia A. In the context of bleed treatment with porcine factor, followed by emicizumab, a standardized, algorithmic approach can be effectively employed for these patients. Though any patients have inhibitor recurrence, as is described in the literature, with emicizumab available, bleeding can be avoided with regular monitoring. Emicizumab given while re-eradicating an inhibitor can prevent morbidity of this disease. Figure 1 Figure 1. Disclosures Ellsworth: Takeda: Other: Salary supported as part of NHF-Takeda Clinical Fellowship Award. Key: Uniqure: Consultancy, Other: Participation as a clinical trial investigator; Grifols: Research Funding; Takeda: Research Funding; BioMarin: Honoraria, Other: Participation as a clinical trial investigator; Sanofi: Consultancy. Ma: Accordant: Consultancy; Takeda: Honoraria, Research Funding. OffLabel Disclosure: Emicizumab is not approved for use in Acquired Hemophilia A and this represents an OFF LABEL use of the drug.

Exposure-Response Relationship between Von Willebrand Factor (VWF) Activity and Bleeding Events Following Prophylaxis with Recombinant VWF (rVWF, vonicog alfa) in Patients with Severe Von Willebrand Disease (VWD)

Background: rVWF (vonicog alfa; Vonvendi ®,Baxalta US Inc, a Takeda company, Lexington, MA, USA) is a purified recombinant VWF concentrate approved for on-demand (OD) treatment of hemorrhage and management of surgical bleeding in adults with VWD. The efficacy and safety of rVWF prophylaxis has also been evaluated in a recent open-label phase 3 trial in adults with severe VWD (NCT02973087). Aims: To evaluate the exposure-response (ER) relationship between VWF activity (measured by VWF:ristocetin cofactor [RCo]), endogenous factor VIII (FVIII) activity (measured by FVIII:C), and spontaneous bleeding events (sBEs) in patients with severe VWD receiving rVWF prophylaxis for up to 1 year. Methods: The modeling framework involved developing population pharmacokinetic (PK) and PK/pharmacodynamic (PD) models and conducting simulations to characterize VWF activity/PK and FVIII activity/PD, then developing an ER model for VWF and FVIII activities in association with sBEs. The population PK and PK/PD models were developed using data from 100 unique patients receiving intravenous rVWF in 4 completed clinical studies (NCT00816660; NCT01410227; NCT02283268; NCT02973087). The PK and PK/PD analyses were used to generate model parameters and evaluate predictors of heterogeneity for PK/VWF:RCo and PD/FVIII:C time profiles. The ER relationship was evaluated using sBEs from the phase 3 rVWF prophylaxis trial (NCT02973087) in 23 adults with severe VWD (VWF:RCo <20 IU/dL) requiring VWF therapy to manage BEs during the year before study entry: 13/23 patients were previously treated OD with a VWF (Prior OD group) and 10/23 had received plasma-derived VWF (pdVWF) prophylaxis (Switch group). For this ER evaluation, a repeated time-to-event (RTTE) model was used, including a piecewise exponential additive model, and the covariate effect of previous treatment (OD with a VWF or prophylaxis with pdVWF) was explored. Model selection was performed by comparing the goodness of fit of linear and nonlinear ER models based on the PK and PK/PD models' predicted values for 1) VWF:RCo and FVIII:C trough levels; 2) average VWF:RCo and FVIII:C levels in dosing interval; and 3) average VWF:RCo and FVIII:C levels over 24 h following rVWF treatment, with comparisons of these levels before sBE onset in patients with and without sBEs. The PK and PK/PD models were also used to derive the VWF:RCo and FVIII:C levels for pdVWF, and these were applied to the ER model. The impact of the dosing regimens (twice weekly [BIW] or once weekly [QW]) on the ER for rVWF and pdVWF were investigated based on population simulations. Hazard ratios (HRs) for the probability of bleeding were generated as a function of median VWF activity at steady state for patients with type 3 VWD. Results: The RTTE model with a linear ER function linking the average levels of VWF:RCo or FVIII:C over 24 h before sBE onset was selected as the best model. A statistically significant ER relationship was observed (p<0.05) for the ER model with VWF:RCo, in which higher exposure to VWF:RCo was associated with a lower risk of sBE occurrence. The covariate effect of previous treatment (OD with a VWF or prophylaxis with pdVWF) was not statistically significant (p=0.6732). Simulations suggested that the HR per 10 IU/dL increment in the average exposure of VWF:RCo 24 h before an sBE was 0.673 (95% CI: 0.454-0.999). The HR per 20 IU/dL increment in the average exposure of VWF:RCo 24 h before an sBE was 0.453 (95% CI: 0.206-0.998). In addition, the predicted risk of a sBE for the 50 IU/kg QW regimen of rVWF and pdVWF was 30% and 43% higher, respectively, compared with the 50 IU/kg BIW regimen of rVWF (ie, reference regimen). The predicted risk of bleeding with the 50 IU/kg BIW regimen of pdVWF was 20% higher compared with the 50 IU/kg BIW regimen of rVWF. A trend was observed for the ER relationship based on FVIII:C (average levels of FVIII over 24 h before the sBE) suggesting a lower risk of sBEs with increased FVIII:C, which was however not statistically significant. Conclusions: Analysis of exposure to VWF:RCo or FVIII:C vs sBE occurrence indicated a causal association between VWF:RCo and sBEs; higher VWF:RCo was associated with a lower sBE risk. This relationship was independent of the patients' previous treatment (OD with a VWF or prophylaxis with pdVWF). Once further supported with additional data, this ER model could be utilized for individualized dosing strategies to optimize patient outcomes with rVWF prophylaxis. Disclosures Wang: Takeda Development Center Americas, Inc.: Current Employment; Takeda: Current equity holder in publicly-traded company. Özen: Takeda Development Center Americas, Inc.: Current Employment; Takeda: Current equity holder in publicly-traded company. Mellgård: Takeda Development Center Americas, Inc.: Current Employment; Takeda: Current equity holder in publicly-traded company. Marier: Certara Strategic Consulting: Current Employment. Barriere: Certara Strategic Consulting: Current Employment. Vasilinin: Certara Strategic Consulting: Current Employment. Bhattacharya: Takeda: Current equity holder in publicly-traded company; Takeda Development Center Americas, Inc.: Current Employment. OffLabel Disclosure: Abstract reports results from a population ER analysis using data from a clinical trial investigating the efficacy and safety of rVWF prophylaxis. rVWF is not currently authorized for use as a prophylactic treatment.

Factor VIII Level Comparison in Patients with Severe Hemophilia a on Emicizumab with Inhibitors with One Stage, Bovine and Human Chromogenic Assays and the Factor VIII Equivalency of Emicizumab Using In Vivo Global Hemostasis Assays

Introduction Emicizumab is a recombinant, humanized bispecific monoclonal antibody that mimics the function of factor VIII (FVIII) which results in a significant reduction in the annualized bleeding rate in patients with hemophilia A (HA), however, the degree with which emicizumab corrects the coagulation defect remains unclear. The objective of this study was to compare the current available laboratory methods in clinical practice; one-stage clotting factor assays (OSCA), bovine and human chromogenic FVIII activity (bovCHR and humCHR, respectively) and FVIII Equivalency of Emicizumab by Thrombin Generation (F8EmT). Aims The aim of this study is to address the differences of FVIII activity with different techniques in patients with severe HA with inhibitors on emicizumab. Materials and Methods Factor VIII levels are determined with an activated partial thromboplastin time (aPTT), OSCA using SynthASil on the ACL TOP 500 (Instrumentation Laboratory, Bedford, MA). Factor VIII activity is also determined photometrically via the Chromogenix Coatest® SP4 FVIII chromogenic assay kit (bovCHR, Diapharma Group, West Chester, OH) and the Biophen FVIII:C chromogenic assay kit (humCHR, Aniara Diagnostica, West Chester, OH). For F8EmT, linear regression was utilized to model the FVIII levels as a function of the endogenous thrombin potential (ETP) and peak thrombin values for patients with mild/moderate hemophilia. Then, we used the ETP and peak thrombin results of the severe HA patients on emicizumab with the calibration curve to calculate their F8EmT. Association between patient weight and their F8EmT were also examined and evaluated by linear regression. Results Data is presented for eight patients with severe HA with inhibitors on emicizumab in the non-bleeding state (Table-1). All patients' FVIII levels measured with OSCA are in or above the normal range (94.0-289.1). Bovine chromogenic FVIII activity is in the severe hemophilia range for five out of eight patients, for the rest it is in the moderate hemophilia range. Human chromogenic FVIII activity ranged between 12.5-49.8%. Factor VIII Equivalency of Emicizumab by Thrombin Generation is either in the mild hemophilia or normal range in all participants of the study. Conclusion One-stage clotting factor assays demonstrated falsely high results as expected since it is activated partial thromboplastin time based. Bovine chromogenic FVIII activity results were consistent with the severe HA range of the patients though a few had results slightly above that level. Previous literature has stated that the humCHR in patients on emicizumab results in FVIII levels of ∼30% when emicizumab is at its therapeutic concentration (∼50 mcg/ml). This study also demonstrated similar results with 5/8 patients having levels 30-50%. F8EMT levels were mostly consistent with the humCHR. In conclusion, understanding the degree to which emicizumab corrects the coagulation defect of is an important goal as it has clinical implications.Certainly, additional studies with higher participant numbers are needed to confirm these findings. Figure 1 Figure 1. Disclosures Young: Apcintex, BioMarin, Genentech/Roche, Grifols, Novo Nordisk, Pfizer, Rani, Sanofi Genzyme, Spark, Takeda, and UniQure: Consultancy; Genentech/Roche, Grifols, and Takeda: Research Funding.

First-in-Human Dose-Finding Study of AAVhu37 Vector-Based Gene Therapy: BAY 2599023 Has Stable and Sustained Expression of FVIII over 2 Years

Background Gene therapy for hemophilia A has the potential to reduce the treatment burden for patients and their care providers by eliminating the need for regular factor VIII (FVIII) prophylaxis through long-term expression of endogenous FVIII at levels sufficient to provide bleed protection. Ongoing phase 3 gene therapy trials for hemophilia A show promise but can result in unpredictable FVIII expression of uncertain durability. Gene therapy must evolve to meet patient expectations of a durable, efficacious and safe treatment. BAY 2599023 (AAVhu37.hFVIIIco) is the first, clinical stage adeno-associated virus (AAV) gene therapy vector, based on the AAVhu37 serotype. BAY 2599023 is a non-replicating AAV vector and contains a single-stranded DNA genome encoding a B-domain-deleted FVIII, under the control of a liver-specific promoter/enhancer combination, optimized for transgenic expression. The AAVhu37 capsid is a member of the hepatotropic clade E family and was selected based on preclinical studies demonstrating efficient, liver-directed FVIII gene transfer, favorable biodistribution and durable FVIII expression. Here, we report safety and FVIII activity levels achieved to date in this first-in-human, dose-finding study of BAY 2599023. Methods The ongoing BAY 2599023 phase 1/2, open-label, dose-finding study (NCT03588299) included male patients aged ≥18 years with severe hemophilia A, no history of FVIII inhibitors, no detectable neutralizing immunity against AAVhu37 (neutralizing antibody titer ≤5), and ≥150 exposure days to FVIII products. Patients received a single intravenous infusion of BAY 2599023 and were enrolled sequentially into three dose cohorts (0.5 × 10 13 GC/kg, 1.0 × 10 13 GC/kg and 2.0 × 10 13 GC/kg), each comprising at least two patients. Patients to be enrolled in a fourth cohort will receive a single infusion of 4 × 10 13 GC/kg (Figure 1). Primary endpoints were adverse events (AEs), serious AEs (SAEs) and AEs/SAEs of special interest (S/AESIs). The secondary endpoint was FVIII activity over time. Informed patient consent and ethics committee approval were obtained. Results Three cohorts of ≥2 patients each (N = 9) were enrolled sequentially (Figure 1). At the data cutoff (May 2021), FVIII activity data were available for the first eight patients. BAY 2599023 delivered sustained FVIII expression levels for up to >23 months, with evidence of bleed protection. Patients in Cohorts 2 and 3 have all been off prophylaxis with FVIII products since approximately 6-12 weeks after gene transfer. To date, it has been observed that no spontaneous bleeds requiring treatment have been reported once FVIII levels >11 IU/dL were achieved. Of the 9 patients treated, 5 patients developed an AESI: mild/moderate alanine aminotransferase (ALT) elevations observed in Cohort 2 (n =1) and Cohort 3 (n = 3) were managed with corticosteroid treatment; another ALT elevation was reported as study-drug-related SAE in Cohort 3 (n = 1) but returned to normal a few weeks after interruption of the H2 blocker famotidine. The latest follow-up data for up to 28 months will be presented. Conclusions BAY 2599023 was designed to enhance efficacy and durability of FVIII expression with a favorable safety profile. Sustained FVIII levels allowed suspension of FVIII prophylaxis in the majority of patients, with asymptomatic ALT elevations that responded to corticosteroids, making BAY 2599023 a key candidate in the evolution of gene therapy in hemophilia A. Figure 1 Figure 1. Disclosures Pipe: Genventiv: Consultancy; Regeneron/ Intellia: Consultancy; uniQure: Consultancy, Other; Spark Therapeutics: Consultancy; Takeda: Consultancy; Sanofi: Consultancy, Other; Sangamo Therapeutics: Consultancy; Roche/Genentech: Consultancy, Other; Pfizer: Consultancy; Novo Nordisk: Consultancy; Freeline: Consultancy, Other: Clinical trial investigator; HEMA Biologics: Consultancy; CSL Behring: Consultancy; Catalyst Biosciences: Consultancy; Biomarin: Consultancy, Other: Clinical trial investigator; Bayer: Consultancy; ASC Therapeutics: Consultancy; Apcintex: Consultancy; Grifols: Consultancy; Octapharma: Consultancy; Shire: Consultancy. Sheehan: BioMarin: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Bayer: Consultancy, Research Funding. Coppens: Portola/Alexion: Research Funding; CSL Behring: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Roche: Research Funding; Daiichi Sankyo: Research Funding; Sanquin Blood Supply: Research Funding; uniQure: Research Funding; Medcon International: Consultancy; MEDtalks: Consultancy; Novo Nordisk: Consultancy; Pfizer: Consultancy; Sobi: Consultancy. Eichler: Takeda: Consultancy, Honoraria; BioMarin: Consultancy, Research Funding; Roche: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; CSL Behring: Consultancy, Honoraria; Pfizer: Research Funding; Novo Nordisk: Consultancy, Research Funding; Biotest: Consultancy, Honoraria; Bayer: Consultancy, Research Funding. Linardi: Bayer: Current Employment. Wiegmann: Bayer: Current Employment. Hay: Pfizer: Consultancy, Research Funding; Inspiration: Consultancy, Honoraria; BioMarin: Consultancy, Honoraria; Roche: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Spark Therapeutics: Consultancy, Research Funding. Lissitchkov: Bayer: Other: Principal Investigator of Clinical Trials; Catalist: Other: Principal Investigator of Clinical Trials; Grifols: Other: Principal Investigator of Clinical Trials.

The Effects of Tranexamic Acid on Bleed Control, Coagulopathy and Survival with Trauma in Anemic Mice

Clinical evidence suggests that anemia increases surgical bleeding and is associated with poor outcomes. Globally, ~ 50% of anemia is attributed to iron deficiency as the most common nutritional disorder. To study the effects of iron deficiency anemia (IDA) on traumatic bleeding we developed a mouse model of IDA and traumatic injury, and tested the effects of prophylactic tranexamic acid (TXA), on blood loss, coagulopathy and survival. Materials and Methods C57BL/6J mice, both male and female, were fed with usual laboratory ("control mice") or iron deficient (4ppm iron) chow ("IDA mice") starting at 3 weeks of age. After 6 weeks, IDA was documented by blood count, red cell indices and liver iron content. Mice then were subjected to an established liver laceration model causing severe bleeding. Blood loss (weighing blood-soaked sponges in the abdominal cavity), seven-day survival and coagulation parameters (APTT, activity levels of Factor (F) V, FVIII, Fibrinogen) were determined at 15 and 60 minutes after liver laceration for "IDA" and "control mice", treated or not treated five minutes prior to injury with TXA (10mg/kg). All data were expressed as median and were compared using Mann-Whitney test. Results Compared to "control" mice, "IDA mice" developed hypochromic and microcytic anemia with a significantly lower mean hematocrit (32±1.7% vs 49±1.2%, p≤0.0001) and hepatic iron content (75.9±19.8µg/g vs 22.4±9.4 µg/g, p≤0.0001). "IDA mice" demonstrated significantly more bleeding after liver laceration compared to "control mice." Most of the bleeding had occurred at 15 minutes after injury with little incremental bleeding at 60 minutes. The blood loss in "IDA mice" was greater at both time points compared to "control mice" (15 minutes: 21.5±2.3µl/g vs 15.9±2.6µl/g, p≤0.0001; 60 minutes: 24.5±1.6µl/g vs 20.7±1.9µl/g, p≤0.0001). TXA reduced bleeding significantly in "IDA mice" at 15 and 60 min to ~15µl/g. In "control mice", bleed improvement was only present at 60 min (also reduced to ~15µl/g), without improvement below the ~15µl/g baseline threshold at 15 min. Coagulopathy developed in both groups over 60 min, with similar prolongation of the APTT from baseline (23.9±1.5s to 36.0±4.9s in "IDA mice"; 22.8±1.3s 35.0±3.8s in "control mice"), substantial depletion of FV and FVIII activity levels and partial reduction of fibrinogen. TXA administration normalized the APTT only in "control mice" at 60 minutes, but not in "IDA mice", although TXA reconstituted FV and fibrinogen to ~100% activity, with FVIII activity of ~50% in both groups. Survival of "IDA mice" was lower compared to "control mice" (50% vs 75%), but increased significantly with TXA (80%, p=0.04). Conclusion Enhanced bleeding and poorer survival was observed in "IDA mice" compared to "control mice" after liver laceration at similar degrees of coagulopathy. Prophylactic TXA corrected bleeding and reduced mortality in "IDA mice" to values similar to those observed for "control mice" despite incomplete correction of the coagulopathy in "IDA mice". This suggests that TXA may be of particular importance in the face of anemia, by mechanisms that may go beyond hemostasis correction alone, warranting further investigation. Disclosures von Drygalski: CSL Behring: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Research Funding; Novo Nordisk: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hematherix, Inc: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: Super FVa; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Biomarin: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; uniQure: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Low FXIII activity levels in intensive care unit hospitalized COVID-19 patients

Background COVID-19 infection is associated with a hypercoagulable state. Severe COVID-19 patients present with high plasma fibrinogen levels, continuous deposition of fibrin and the presence of microthrombi in their lungs, accompanied by significant fibrinolysis, resulting in high D-dimer levels. Due to the role of FXIII in fibrin crosslinking and clot stabilization, we analyzed its activity levels and dynamics in COVID-19 patients hospitalized in the intensive care unit (ICU). Methods FXIII levels were measured in thirty four COVID-19 patients hospitalized in the ICU and in fourteen non-severe COVID-19 patients. FVIII levels were measured for comparison. Laboratory data and clinical variables were recorded. Results The average FXIII activity level in 34 ICU hospitalized COVID-19 patients was 69.9±33 %, significantly lower compared to an average of 120±20.9 % FXIII activity in 14 non-severe COVID-19 patients. FXIII activity levels were below the low normal value (< 79 % FXIII activity) in 74 % of the ICU hospitalized COVID-19 patients. In contrast, high FVIII activity was measured among all severe COVID-19 patients. Consecutive measurements, performed in fourteen ICU hospitalized COVID-19 patients, pointed to a significant decrease in FXIII activity from the average of 85.7±28.2 %, (which is in the normal range), to an average of 68.0±20.4 %, below the low normal range, within 6.4±3.4 days of ICU hospitalization. Liver functions did not differentiate between patients with low and normal FXIII activity. No inhibitor to FXIII activity was found in the plasma of severe COVID-19 patients. Levels of FXIII-A antigen correlated with FXIII activity, and were low in severe COVID-19 patients. Conclusions Low FXIII activity levels were found in COVID-19 patients hospitalized in the ICU, with gradual decline during their hospitalization. A mechanism of consumption may account for the low FXIII activity in these patients.

Congenital hemophilia A with low activity of factor XII: a case report and literature review

Background Congenital hemophilia A is a recessive inherited hemorrhagic disorder. According to the activity of functional coagulation factors, the severity of hemophilia A is divided into three levels: mild, moderate and severe. The first bleeding episode in severe and moderate congenital hemophilia A occurs mostly in early childhood and mainly involves soft tissue and joint bleeds. At present, there are limited reports on severe congenital hemophilia A with low factor XII (FXII) activity during the neonatal period. Case presentation A 13-day-old neonate was admitted to the hospital with hematoma near the joints of both upper arms. Coagulation tests showed he had low activity of factor VIII (FVIII) and FXII. He was diagnosed with congenital hemophilia A and treated with human coagulation factor VIII (recombinant FVIII). Although the hematoma became smaller, FVIII activity was only increased to a certain extent and FXII activity decreased gradually. Unfortunately, the child responded poorly to recombinant human coagulation factor VIII and his guardian rejected prophylactic inhibitors and genetic testing and refused further treatment. Three months later, the child developed intracranial hemorrhage (ICH) due to low FVIII activity. Conclusions In hemophilia A, the presence of FVIII inhibitors, drug concentration and testing are three important aspects that must be considered when FVIII activity does not reach the desired level. Early positive disease treatment and prophylaxis can decrease the frequency of bleeding and improve quality of life. We recommend that pregnant women with a family history of hemophilia A undergo early prenatal and neonatal genetic testing.