Coagulation Factor Inhibitors Research Articles

Coagulation factor inhibitors in COVID‐19: From SARS‐CoV‐2 vaccination to infection

BackgroundRecent reports have highlighted patients with COVID‐19 and vaccine recipients diagnosed with coagulation factor inhibitors. This is challenging. as severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection has been identified as a prothrombotic risk factor, with heparin treatment decreasing mortality. However, both infection and vaccination have been associated with immune‐mediated hematologic abnormalities, including thrombocytopenia, further rendering these groups at risk for both hemorrhagic and thrombotic events. ObjectivesWe sought to characterize the incidence and clinical findings of coagulation factor inhibitors in patients with COVID‐19 and vaccine recipients. MethodsWe queried the US Centers for Disease Control and Prevention’s Vaccine Adverse Event Reporting System (VAERS), a publicly accessible database, for reports of potential bleeding episodes or coagulation disturbances associated with SARS‐CoV‐2 vaccination. We performed an additional comprehensive literature review to identify reports of SARS‐CoV‐2 infection or vaccination‐associated coagulation factor inhibitors. ResultsVAERS data showed 58 cases of coagulation factor inhibitors, suggesting a rate of 1.2 cases per 10 million doses. A total of 775 articles were screened and 15 were suitable for inclusion, with six reports of inhibitors after vaccination and nine reports of inhibitors after infection. Inhibitor specificity for factor VIII was most common. Among reported cases, two patients expired due to hemorrhage, one following infection and one following vaccination. ConclusionThe incidence of coagulation factor inhibitors in patients with SARS‐CoV‐2 vaccination and infection appears similar to the general population. Nonetheless, given the importance of heparin therapy in treating hospital patients, recognition of inhibitors is important.

Anticoagulation polyvinyl chloride extracorporeal circulation catheters for heparin-free treatment.

Extracorporeal circulation (ECC) catheters have potential to be blood compatible and could be used to prevent thrombotic occlusion. Here, we produced heparin-mimicking anticoagulation PVC tubing on a large scale by synthesizing a heparin-mimicking polymer (HMP) and co-extruding. The PVC@HMP catheter was evaluated using whole human blood in vitro, which indicated it could prevent plasma protein attachment, reduce platelet adhesion and activation, and inhibit coagulation factors (XII, XI, IX, and VIII). Moreover, the anticoagulation PVC tubing was assembled into extracorporeal circulation with a New Zealand rabbit model, manifesting excellent real-time antithrombogenic properties without systemic heparin anticoagulation in vivo. The rapid recovery of coagulation factors after operation further confirmed its superiority over heparin, which would not completely inactivate the activity of those coagulation factors (XII, XI, IX and VIII). In addition, the PVC@HMP-1 catheters remain patent after being implanted in rats for 28 days without apparent inflammation and mortality complications. The anticoagulation PVC tubes could be used to construct various systemic and integrative anticlotting biomedical devices, which would dramatically reduce the introduction of heparin into blood circulation, thus preventing side effects and promoting the development of heparin-free treatment.

POSC14 Frequency of Complications in a Cohort of Patients Diagnosed with Hemophilia Undergoing Prophylactic Treatment at a Health Care Institution in Colombia: A Retrospective Non-Interventional Study

Hemophilia A and B are disorders associated with the deficit of coagulation factors VIII and IX that increase the risk of bleeding and complications (clotting factor inhibitor antibodies, severe bleedings, hospitalizations and anaphylactic reactions) depending on the severity of the disorder. The objective of this study was to determine the incidence of complications in a cohort of patients diagnosed with moderate and severe hemophilia A or B under treatment in a specialized institution.

Direct oral anticoagulant (DOAC) interference in hemostasis assays

Abstract Direct oral anticoagulants (DOACs) are a group of direct coagulation factor inhibitors including both direct thrombin inhibitors and direct factor Xa inhibitors. These medications may cause hemostasis assay interference by falsely increasing or decreasing measured values, depending on the analyte. Considering the potential for DOAC interference in a variety of hemostasis assays is essential to avoid erroneous interpretation of results. Preanalytic strategies to avoid DOAC interference include selecting alternatives to clot-based hemostasis assays in patients taking DOACs when possible and sample collection timed when the patient is off anticoagulant therapy or at the expected drug trough. Clinical laboratories may also provide educational materials that clearly describe possible interferences from DOAC, develop testing algorithms to aid in detection of DOAC in submitted samples, use DOAC-neutralizing agents to remove DOACs before continuing with testing, and write interpretive comments that explain the effects of DOAC interference in hemostasis tests. Using a combination of the described strategies will aid physicians and laboratorians in correctly interpreting hemostasis and thrombosis laboratory tests in the presence of DOACs.

Diagnosis and Treatment of Acquired Hemophilia: One Single-Center Experience from PR. China

Objective: To deepen the understanding of the clinical manifestations of acquired hemophilia A for timely and correctly treatment.Methods: The clinical data of the acquired hemophilia A patients diagnosed in the hospital from Jan 2006 to Mar 2021 were retrospectively analyzed, and the relevant literature was reviewed.Results: 17 patients with acquired hemophilia A, male: female =10: 7, median age 61 years (19 to 78 years), were diagnosed and treated in the hospital with the median time from the onset to diagnosis 21 days (2 days to 6 months). Six patients had comorbidity, including hepatitis B carrying, chronic myelomonocytic leukemia, diabetes, hypertension and positive autoantibodies, pemphigoid and gastric cancer, respectively. Other 11 patients were healthy before the onset. All patients had large large ecchymosis of skin, and one case was combined with hematuria, and one case with retroperitoneal hematoma. All patients had APTT extension (45s-144.7s) and the prolonged APTT could not be corrected with normal mixed plasma with and without incubation at 37℃ for 2 hours. FVIII activity was 1% - 8.9% and inhibitor titer 2 - 128 Bu/ml. All patients with bleeding were with prothrombin complex/recombinant activated coagulation factor VII, some of them with pd-coagulation factor FVIII preparations. Inhibitors were removed with prednisone acetate (1 case) + chemotherapy (1 case), prednisone acetate / + CTX (11 cases) + chemotherapy (1 case), prednisone acetate/prednisolone + mabthera (2 cases) + CTX (1 case), respectively. The removal time of inhibitor was from 8 days to 4 years. During the treatment process, two patients developed lower extremity venous thrombosis, and one patient was complicated with lung infection.Conclusion: Patients with unexplained bleeding and prolonged APTT should be conducted normal mixed plasma correction test, coagulation factor activity and inhibitor titer examination. After correctly diagnosis, bypass agents /coagulation factor VIII preparations should be given timely for hemostasis, protocol based on glucocorticoid + CTX/mabthera to remove the inhibitor and symptomatic treatment for patients with primary comorbidity disease at the same time. DisclosuresNo relevant conflicts of interest to declare.

Generation of a humanized FXII knock‐in mouse—A powerful model system to test novel anti‐thrombotic agents

BackgroundEffective inhibition of thrombosis without generating bleeding risks is a major challenge in medicine. Accumulating evidence suggests that this can be achieved by inhibition of coagulation factor XII (FXII), as either its knock‐out or inhibition in animal models efficiently reduced thrombosis without affecting normal hemostasis. Based on these findings, highly specific inhibitors for human FXII(a) are under development. However, currently, in vivo studies on their efficacy and safety are impeded by the lack of an optimized animal model expressing the specific target, that is, human FXII. ObjectiveThe primary objective of this study is to develop and functionally characterize a humanized FXII mouse model. MethodsA humanized FXII mouse model was generated by replacing the murine with the human F12 gene (genetic knock‐in) and tested it in in vitro coagulation assays and in in vivo thrombosis models. ResultsThese hF12KI mice were indistinguishable from wild‐type mice in all tested assays of coagulation and platelet function in vitro and in vivo, except for reduced expression levels of hFXII compared to human plasma. Targeting FXII by the anti‐human FXIIa antibody 3F7 increased activated partial thromboplastin time dose‐dependently and protected hF12KI mice in an arterial thrombosis model without affecting bleeding times. ConclusionThese data establish the newly generated hF12KI mouse as a powerful and unique model system for in vivo studies on anti‐FXII(a) biologics, supporting the development of efficient and safe human FXII(a) inhibitors.

Measurement of coagulation factor antibody levels is useful for diagnosis and determining therapeutic efficacy in hemorrhagic patients with autoantibodies to coagulation factor VIII and factor V: results from a single center in Japan

Coagulation factor inhibitors (CFIs) sometimes cause fatal bleeding conditions. Determination of an inhibitor titer (INH-titer) using the Bethesda method is essential for diagnosing diseases associated with CFIs and examining the effects of immunosuppressive therapy. We reviewed 17 cases with CFIs (acquired hemophilia A, n = 11; FV inhibitor, n = 6) to examine the usefulness of determining quantities of an autoantibody to a coagulation factor (CF-IgG) by ELISA for diagnosis and therapeutic efficacy, as compared with INH-titer. One patient with an INH-titer and no evidence of CF-IgG was lupus anticoagulant (LA)-positive, and thus the positive INH-titer may have been a false positive caused by LA. Although INH-titer alone was insufficient to correctly identify patients with CFI, determination of CF-IgG appeared to be useful. In addition, even after INH-titer disappearance, hemorrhagic conditions recurred when CF-IgG was detected. These findings suggest that the presence of a clearance antibody against the coagulation factor might reduce the activity of that coagulation factor even after disappearance of the corresponding neutralizing antibody. Although the diagnosis and therapeutic efficacy can also be determined by INH-titer disappearance and improvement of corresponding coagulation factor activity, determination of CF-IgG by ELISA can improve the accuracy of these assessments.

Prospective study examining the use of thrombin–gelatin matrix (Floseal) to prevent post dental extraction haemorrhage in patients with inherited bleeding disorders

The bleeding risk in individuals with inherited bleeding disorders (IBDs) during exodontia is traditionally managed with perioperative coagulation factors and/or desmopressin, in conjunction with systemic and topical perioperative tranexamic acid and meticulous primary closure. Factor replacement is costly, requires specialist input, and carries a risk of developing factor VIII (FVIII) inhibitors. This prospective study was performed to determine whether the use of a standardized Floseal and anti-fibrinolytic protocol could reduce postoperative bleeding in patients with IBDs undergoing dental extraction, as compared to factor replacement. All patients >18 years old attending Queensland Haemophilia Centre between November 2014 and July 2019 who required dental extractions were referred to the Oral and Maxillofacial Unit. Patients were consented for intraoperative Floseal administration instead of factor replacement. All other operative measures remained the same. The bleed rate was assessed against a historical control cohort. There were 34 extraction events in 32 patients. Four of the patients reported postoperative bleeding requiring factor supplementation or desmopressin; the bleeding rate was 11.8%. While not statistically significant, this was a reduction in the bleed rate compared to the traditional protocol (P = 0.35). Third molar extractions were 10.33 times more likely to cause postoperative bleeding (P = 0.018). The Floseal protocol was equipotent to the traditional perioperative factor replacement protocol. Floseal use is more economical, eliminates the risk of peri-procedural FVIII inhibitor development, and provides a haemostatic option for patients with very rare factor deficiencies, pre-existing clotting factor inhibitors, and those with anaphylaxis to clotting concentrates.

Effective Management of a Patient with Acquired Coagulation Factor Inhibitors Using Therapeutic Plasma Exchange Alone

Rae Na, M.D., Kyong-Suk Ryu, Min-Sun Kim, M.D., John Jeongseok Yang, M.D., Han-Seung Park, M.D., Seongsoo Jang, M.D., Sang-Hyun Hwang, M.D., Heung-Bum Oh, M.D., Dae-Hyun Ko, M.D.. Lab Med Online 2021;11:203-7. https://doi.org/10.47429/lmo.2021.11.3.203

Clinical Outcomes of Acquired Factor VIII Inhibitors in Cancer Population: A Systematic Review

Background: In cancer patients, the development of autoantibodies against coagulation factors is a rare but a life-threatening bleeding disorder. Acquired hemophilia A (AHA) is the most common subset of the disorder and is caused by the inhibitory antibodies against coagulation factor VIII (FVIII) activity which can cause significant bleeding diathesis in those patients. Therefore, a prompt diagnosis is necessary for management of controlling the suppression of the inhibitor and the bleeding diathesis.Aims: We conducted a systematic review to study the occurrence of FVIII inhibitors in cancer patients, particularly their clinical outcomes and treatment responses.Methods: We performed an electronic search through March 31, 2017 with search terms “acquired hemophilia factor VIII inhibitor and cancer”, “acquired hemophilia A” in PUBMED and EMBASE. Manuscripts with unavailable details, other coagulation factor inhibitors, hereditary cases and in other languages were excluded. The primary endpoint was measuring clinical response to treatments as defined by reduction of at least 50% in the baseline FVIII inhibitor level. Secondary endpoints were identifying early (defined a time to response ≤ 1.5 months from the initiation of therapy) vs. late responders to treatments and overall survival (OS) between responders and non-responders.Results:47 cases of AHA associated with malignancies were analyzed. Several cancer and hemophilia characteristics were compared between treatment responders and non-responders. Findings include 68% males, median age 70 (58-74), hematologic vs. solid malignancy of 62% vs. 38%, median FVII inhibitor level 14 BU/mL. The most common therapy used to eradicate the inhibitor was immunosuppressive therapy; differences in treatment modalities did not result in significant differences between responders and non-responders (Table 1). Treatment responders have lower median FVII inhibitor level as compared to non-responders (12 vs. 41 BU/mL; p = 0.027). There was equal number of cases for early and late responders. Median OS for responders was 41 months with 95 % CI [10.7-71.3] vs. 2 months for non-responders with 95% CI [1.3-2.7].Conclusion:The amount of inhibitor overall seems to be the best predictor of clinical outcomes in AHA patients regardless of the type of therapy used and the type of malignancy. Earlier detection of FVIII inhibitors could lead to earlier interventions with suppression therapy, potentially improving outcomes. Larger studies are needed to confirm our findings. [Display omitted] DisclosuresRojas Hernandez:Daichii Sankyo: Research Funding. Oo:Daichii Sankyo: Research Funding.

Genetically Proxied Inhibition of Coagulation Factors and Risk of Cardiovascular Disease: A Mendelian Randomization Study.

BackgroundWe conducted Mendelian randomization analyses investigating the linear associations of genetically proxied inhibition of different coagulation factors with risk of common cardiovascular diseases.Methods and ResultsGenetic instruments proxying coagulation factor inhibition were identified from genome‐wide association studies for activated partial thromboplastin time and prothrombin time in BioBank Japan (up to 58 110 participants). Instruments were identified for 9 coagulation factors (fibrinogen alpha, beta, and gamma chain; and factors II, V, VII, X, XI, and XII). Age‐ and sex‐adjusted estimates for associations of the instruments with the outcomes were derived from UK Biobank and the FinnGen, CARDIoGRAMplusC4D (Coronary Artery Disease Genome‐wide Replication and Meta‐analysis), and MEGASTROKE consortia with numbers of incident and prevalent cases of 820 to 60 810. Genetically proxied inhibition of fibrinogen alpha, beta, and gamma chain, factor II, and factor XI were associated with reduced risk of venous thromboembolism (P<0.001). With the exception of fibrinogen beta and factor II, inhibition of these factors was also associated with reduced risk of any ischemic stroke and cardioembolic stroke (P≤0.002). Genetically proxied inhibition of fibrinogen beta and gamma were associated with reduced large‐artery stroke risk (P=0.001). There were suggestive protective associations of genetically proxied inhibition of factors V, VII, and X with ischemic stroke (P<0.05), and suggestive adverse associations of genetically proxied inhibition of factors II and XII with subarachnoid hemorrhage.ConclusionsThis study supports targeting fibrinogen and factor XI for reducing venous thromboembolism and ischemic stroke risk, and showed suggestive evidence that inhibition of factors V, VII, and X might reduce ischemic stroke risk.

Selection and in vitro and in vivo characterization of a Kunitz protease inhibitor domain of protease nexin 2 variant that inhibits factor XIa without inhibiting plasmin

The 57-amino acid Kunitz Protease Inhibitor (KPI) domain of Protease Nexin 2 inhibits Factor XIa (FXIa) and other proteases. We previously fused KPI to human serum albumin (KPIHSA). KPIHSA inhibits coagulation Factor XIa (FXIa) 6-fold more rapidly than plasmin. We screened a bacterial expression library of KPI variants randomized at M17, and selected M17D as having the highest anti-FXIa: antiplasmin activity ratio. Expressed as HSA fusion proteins in Pichia pastoris, KPIHSA and KPI(M17D)HSA inhibited FXIa indistinguishably (Ki 9 nM) but KPI(M17D)HSA lacked detectable antiplasmin activity. Purified variant and wild-type KPIHSA were expressed and injected into mice with ferric chloride-treated carotid arteries, with or without systemic administration of tissue plasminogen activator (Tenecteplase, TNKase). The time to arterial occlusion (TTO) or reperfusion (TTR) was assessed by Doppler ultrasound. TTR did not differ between mice treated with TNKase alone or with TNKase supplemented with 38 mg/kg KPI(M17D)HSA but was significantly prolonged to >60 min in all mice treated with TNKase and 38 mg/kg KPIHSA. TTO was significantly but equally prolonged by either 38 mg/kg KPIHSA or KPI(M17D)HSA versus vehicle controls. The antiplasmin activity of KPI is relevant in vivo but its elimination did not enhance counter-thrombosis by KPI.

Acquired hemophilia A that required surgical hemostasis of hematomas occupying oral cavity: a case report

BackgroundAcquired hemophilia A is a rare coagulopathy caused by inhibitors of blood coagulation factor VIII. Patients with acquired hemophilia A have a higher mortality risk (5–10%) than those with congenital hemophilia. Moreover, there is no established evidence of management recommended for patients with acquired hemophilia A. Previous studies have reported the presence of hematomas in the oral cavities of patients with acquired hemophilia A, which were treated conservatively. Here, we describe the case of a patient with acquired hemophilia A, where emergency surgical hemostasis was required for large intraoral hematomas.Case presentationA 65-year-old Japanese man was referred to our hospital with a chief complaint of bleeding from large intraoral hematomas. On examination, he could not close his mouth because of the hematomas, which were bleeding spontaneously. Computed tomography angiography revealed no evidence of arteriovenous malformation, and blood test results showed that the activated partial thromboplastin time was elevated beyond the normal limit. To avoid a life-threatening hemorrhage from hematomas, emergency surgical hemostasis was performed with nasotracheal intubation using fiberoptic bronchoscopy. Hemostasis was successfully performed, as the hematomas were carefully removed. Moreover, the clinical course was successfully completed using intravenously administered activated prothrombin complex concentrate for hemostasis after operation.ConclusionsAcquired hemophilia A can cause a life-threatening hemorrhage without predictive factors. Intraoral hematoma may cause airway obstruction. There is no consensus regarding the management of hemorrhage in patients with acquired hemophilia A. As shown here, exophytic hematomas in the oral cavity can be safely removed and nasotracheal intubation with fiberoptic bronchoscopy may be useful in patients with coagulopathy disease.

Inhibitor Index in the Clot Waveform Analysis-Based Mixing Test Differentiates among Hemophilia A without and with Inhibitors, and Lupus Anticoagulant.

The mixing test is used to identify the pathway to follow-up testing and is also useful for the investigation of lupus anticoagulant (LA) positivity. "To completely correct" indicates clotting factor deficiency, while "to not correct" indicates the presence of a clotting factor inhibitor including LA. "Index of circulation anticoagulant" and/or "percent correction" is used to interpret the results of mixing studies, but it does not accurately differentiate factor inhibitors from LA. To precisely differentiate hemophilia A (HA), HA with inhibitor (HA-inh), and LA using the clot waveform analysis (CWA)-based mixing test. Plasma samples from HA, LA, and HA-inh including acquired HA were incubated with normal plasma in 9:1, 1:1, and 1:9 mix ratios. From activated partial thromboplastin time CWA at 0-minute (immediately) and 12-minute incubation, the ratios of CWA parameters at 12 minutes/0 minute (inhibitor index) were assessed. The inhibitor index values of CWA parameters obtained using the mixing test in a 1:1 ratio demonstrated a significant difference between HA-inh and LA but could not differentiate LA from HA-inh completely. Plasmas used for the mixing tests in 9:1 and 1:9 ratios were able to fully distinguish between HA-inh (>0.5 BU/mL) and LA. These indices significantly correlated with inhibitor titer below 40 BU/mL (r > 0.90), possibly estimating FVIII inhibitor titer from the inhibitor index. Plasmas in HA and LA could be distinguished by mixing in a 1:1 ratio at 0 minute (immediately). The inhibitor index from CWA-based mixing tests with a 12-minute incubation could differentiate among HA, HA-inh, and LA quickly.

Preparation, Characterization and Ex vivo Permeability Study of Transdermal Apixaban O/W Nanoemulsion Based Gel

This study designed to prepare ultrafine apixaban (APX) o/w nanoemulsion (NE) based gel with droplet size below 50 nm as a good method for transdermal APX delivery without using permeation enhancer, alternatively, the formulation components itself act as permeation enhancer. APX, a potent oral anticoagulant drug that selectively and directly inhibit coagulation factor Xa, was selected as a good candidate for transdermal delivery as it displays poor water solubility (0.028 mg/mL) and low bioavailability (50%). APX-NE gel was prepared using triacetin, triton-x-100 and carbitol as oil phase, surfactant and cosurfactant respectively, while Carbopol 940 used as a gelling agent. Ex vivo permeation of APX-NE gel through human stratum corneum reveal

Treatment of Acquired Hemophilia a with Rituximab and Emicizumab

Background Acquired hemophilia A is a rare bleeding disorder caused by autoantibodies that inhibit coagulation factor VIII (FVIII). The disorder is understudied given its rarity and there are no randomized prospective trials to guide therapy. In practice, treatment involves attaining hemostasis and eliminating the FVIII inhibitor, typically with high-dose steroids (1 mg/kg daily) and either cyclophosphamide or rituximab. However, current approaches carry risk of significant adverse events and delayed or inadequate responses. Emicizumab is a bispecific antibody that targets coagulation factors IXa and X to recapitulate the function of endogenous FVIII. We present a case series of patients with acquired hemophilia A who were successfully treated with a regimen consisting of rituximab and emicizumab. Methods We identified patients &amp;gt;18 years who were diagnosed with acquired hemophilia A and received treatment with rituximab and emicizumab at Brigham and Women's Hospital between 2019 and 2020. We performed a retrospective chart review. Data collected included the patients' clinical presentation, laboratory studies (including coagulation testing, FVIII activity, and FVIII inhibitor titer), and treatments received (including systemic therapies, recombinant factor VIIa [rFVIIa], red blood cell [RBC] transfusions, and vascular embolization). We recorded the time to normalization of the activated partial thromboplastin time (aPTT) and chromogenic FVIII activity following emicizumab and rituximab initiation, respectively. Activated prothrombin complex concentrate was avoided given the use of emicizumab. Results We identified 8 patients with acquired hemophilia A who received treatment with emicizumab and rituximab. The median patient age was 81 (range 47-93). All patients sought medical attention for extensive ecchymoses or bleeding and were found to have prolonged aPTT leading to FVIII inhibitor identification (Table 1). The median inhibitor titer was 18 Bethesda units (range 9.2-107.5). Patients concurrently received 4 weekly doses of rituximab 375mg/m2 and 4 weekly loading doses of emicizumab 3mg/kg. Patient (Pt) #1 continued emicizumab 3mg/kg every two weeks to complete three months of treatment. Pts #2, #3, and #8 received high-dose prednisone (1mg/kg) at the start of treatment for a range of 10-14 days. Pt #8 received 7 additional days of prednisone for an initial aPTT of 60.7 seconds before starting emicizumab and rituximab; she had no clinical response when treated with prednisone alone. Pts #2, #5, and #7 required vascular embolization. 7 patients (Pts #2 through #8) had aPTT retested within 1 week of starting emicizumab, and the aPTT for these patients normalized within 10 days of starting emicizumab (i.e. after only 1-2 doses; Figure 1). Except for Pt #5 who had recurrent hematuria from a persistent anatomic bladder defect that eventually required prostatic artery embolization, patients did not require rFVIIa or RBC transfusions for more than 7 days after starting emicizumab. Except for Pt #5 who required 28 doses of rFVIIa and 3 units of RBC transfusions after starting emicizumab, the median number of rFVIIa doses and RBC units given to the remaining 7 patients was zero (range 0-6 doses) and zero (range 0-4 units), respectively. Pts #2 and #3 had chromogenic FVIII levels obtained &amp;gt;30 days after starting rituximab with improvement in FVIII activity to 29% (day 71) and 86% (day 91), respectively. During a median follow-up of 102 days, no patients experienced recurrent bleeding. However, Pt #3 exhibited a slowly increasing aPTT that reached 46.3 seconds on day 233 of follow-up without symptoms; further diagnostic testing is pending. Conclusion Our case series demonstrates that the combination of rituximab and emicizumab can be an effective and safe regimen for the treatment of acquired hemophilia A. No thrombotic events or thrombotic microangiopathy occurred. Treatment with weekly emicizumab led to aPTT normalization after 1-2 doses and facilitated hemostasis, as reflected by a median usage of zero rFVIIA doses and zero RBC transfusions after starting emicizumab when excluding one patient with hematuria from an anatomic defect. This compares favorably to historical reports. While no patient has had recurrent bleeding, additional chromogenic FVIII activity testing for patients is needed to confirm long-term normalization of FVIII activity. Disclosures Gibson: Ampressa therapeutics: Current equity holder in private company; nference: Consultancy, Current equity holder in private company; ImmPACT-Bio: Consultancy; Boston Clinical Research Institute: Consultancy. Parnes:Bayer: Consultancy; I-Mab: Consultancy; Sunovion: Consultancy; UniQure: Consultancy; Sigilon: Consultancy; Shire/Takeda: Consultancy, Research Funding; Genentech: Research Funding; Geron: Current equity holder in publicly-traded company. OffLabel Disclosure: Emicizumab is used off-label in our case series for the treatment of acquired hemophilia A.

Acquired hemophilia A and plasma cell neoplasms: a\xa0case report and review of the\xa0literature

BackgroundAcquired hemophilia A is a rare autoimmune disease with clinically often significant bleeding diathesis resulting from circulating autoantibodies inhibiting coagulation factor VIII. Half of acquired hemophilia A cases are associated with an underlying disorder, such as autoimmune diseases, cancer, or use of certain drugs, or occur during pregnancy and in the postpartum period. In the other half, no underlying cause is identified. An association of acquired hemophilia A with plasma cell neoplasm seems to be extremely rare.Case presentationWe describe a case of a 77-year-old Swiss Caucasian man who was diagnosed with acquired hemophilia A and smoldering multiple myeloma as an underlying cause. Acquired hemophilia A was treated with prednisolone, cyclophosphamide, and immunoadsorption. Extensive workup revealed a plasma cell neoplasm as the only disorder associated with or underlying the acquired hemophilia A. For long-term control of acquired hemophilia A, we considered treatment of the plasma cell neoplasm necessary, and a VRD (bortezomib, lenalidomide, and dexamethasone) regimen was initiated. Due to multiple complications, VRD was reduced to VRD-lite after two cycles. After nine cycles of induction therapy and five cycles of consolidation therapy, the patient is in complete remission of his acquired hemophilia A and very good partial remission of the plasma cell neoplasm. We conducted a literature review to identify additional cases of this rare association and identified 15 other cases. Case descriptions, including the sequence of occurrence of acquired hemophilia A and plasma cell neoplasm , treatment, evolution, and outcome are presented.Discussion and conclusionsOur case, together with 15 other cases described in the literature, underscore the possibility of plasma cell neoplasm as an underlying cause of acquired hemophilia A. Physicians should consider including protein electrophoresis, immunofixation, and analysis of free light chains in laboratory diagnostics when treating a patient with acquired hemophilia A. The occurrence of excessive and unexplained bleeding in patients diagnosed with plasma cell neoplasm should raise suspicion of secondary acquired hemophilia A and trigger the request for coagulation tests, particularly in patients treated with immunomodulatory drugs such as thalidomide or lenalidomide. Additionally, early intervention with immunoadsorption can be lifesaving in cases with high-titer factor VIII inhibitors, especially when surgical interventions are necessary.

Inhibition of platelet aggregation and blood coagulation by a P-III class metalloproteinase purified from Naja atra venom

Snake venom metalloproteinases (SVMPs) are an important component in viperid and crotalid venoms, and these SVMPs play important and versatile roles in the pathogenesis of snakebite envenoming. The SVMPs from elapid venoms are not well elucidated compared with those from viperid and crotalid venoms. Atrase B is a nonhemorrhagic P-III SVMP purified from the Naja atra venom, which possesses a weak fibrinogenolytic activity. In this paper, the activity and mechanism of atrase B against platelet aggregation and blood coagulation were investigated. The in vitro assay showed that atrase B remarkably inhibited ristocetin- and thrombin-induced platelet aggregation by cleavage of the platelet membrane glycoprotein Ib, and the coagulation of normal human plasma, which may be caused by inhibiting coagulation factor VIII predominantly. When atrase B was intravenously injected into rats at doses of 0.05 and 0.30 mg/kg, the activated partial thromboplastin and the thrombin times were significantly prolonged in a dose-dependent manner. Similarly, the fibrinogen level decreased, but only a high dose of atrase B showed remarkable activity against platelet aggregation. Results suggested that anticoagulation was a more important function of atrase B compared with its activity against platelet aggregation. These results indicated that atrase B may play an important role in the anticoagulant properties of Naja atra venom. In addition, atrase B may be a potent anticoagulant agent because its effectiveness in vivo against platelet aggregation and blood coagulation.

In vitro detection and removal of direct oral anticoagulants from patient plasma specimens

: Medical laboratory scientists are often called upon to detect and identify the presence of direct oral anticoagulants in patient plasma, especially in emergent circumstances. Clot-based or chromogenic laboratory assays are often required to detect coagulopathies, coagulation factor inhibitors, or lupus anticoagulants (LA) but are limited by the presence of therapeutic anticoagulants that may invalidate the accuracy of the assay by falsely prolonging clot-based assay intervals and raising chromogenic assay results. We describe a semiquantitative urine reagent strip, DOAC-Dipstick® that may be employed to detect all direct oral anticoagulants and distinguish oral direct thrombin inhibitors (DTI) from oral anti-activated factor X (Xa) inhibitors. A limit of 30 ng/mL was established as the threshold for positivity using the strips. For oral anti-activated factor X inhibitors, the strips’ false positive rate was 4% and false negative rate was 2%. For the oral DTI, the strips’ false positive rate was 0.5% and false negative rate was 0.6%. We further describe four similar devices, DOAC-Stop®, DOAC-Remove®, DP-Filter® and DOAC Filter®, designed to remove direct anticoagulants from plasma by adsorption, filtration and precipitation, while essentially leaving intact native procoagulants suitable for testing. These devices employ activated charcoal (carbon) or similar formulations for adsorption. In LA testing, the DOAC-Stop® device reduces the initial PTT-LA interval for all DOACs by a mean of 21 seconds; there is no reduction for specimens with apixaban, 20 seconds for rivaroxaban, and 25.9 seconds for dabigatran. For the DRVVT assay, DOAC-Stop® removed the anticoagulants from 35 out of 41 specimens. By judiciously selecting and applying these devices and observing their limitations, laboratories may report clot-based and chromogenic substrate results, as alternately affected by DOAC presence, with reasonable confidence.

Optimization of Ultrasound-Assisted Extraction of Functional Food Fiber from Canadian Horseweed (Erigeron canadensis L.)

Much attention has been recently paid to the design of sustainable processes for the production of functional food additives based on renewable resources. Thus, methods for incorporation of green techniques in treatment of undeveloped biomass, resulting in value-added bioproducts, are in great demand. We focus here on the biological activity and chemical properties of Erigeron canadensis (horseweed) functional food fiber, which can be strongly affected by the extraction procedure employed. In the present contribution, we report on an attempt to introduce a sustainable and energy-efficient ultrasound-assisted extraction process, followed by a multistep purification procedure, resulting in a macromolecular plant-derived anticoagulant agent. The most efficient ultrasound-assisted process was determined by optimization through the response surface methodology I-optimal design (24). A comparison with the conventional procedure for retrieval of horseweed biomacromolecules revealed that the optimized ultrasound-assisted extraction was more sustainable, with the cumulative energy demand being 38% lower (12.2 MJ), 6.6 times reduced water consumption (3.5 L), and 1.2 times shorter (41 h) total processing time. Moreover, the optimal ultrasound-assisted extraction process-purified food fiber turned out to be a better anticoagulant agent by 57%, compared to a conventional product, and was a more selective indirect inhibitor of the human Xa coagulation factor.