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.).

Low molecular weight heparin decreases pro-coagulant activity in clinical MSC products.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are multipotent adult cells that can be isolated from tissues including bone marrow [MSC(BM)], adipose [MSC(AT)] and umbilical cord [MSC(CT)]. Previous studies have linked expression of tissue factor (TF) on MSC surfaces to a procoagulant effect. Venous thromboembolism (VTE), immediate blood-mediated inflammatory reaction (IBMIR) and microvascular thrombosis remain a risk with intravascular MSC therapy. We examined the effect of low molecular weight heparin (LMWH) on clinical-grade MSCs using calibrated automated thrombography (CAT). METHODS: Clinical grade MSC(BM)s, MSC(AT)s and MSC(CT)s harvested at passage 4 were added to normal pooled plasma (NPP) to a final concentration of either 400 000 or 50 000 cells/mL. LMWH was added to plasma in increments of 0.1 U/mL. Thrombin generation (TG) was measured using CAT. Flow cytometry was conducted on the cells to measure MSC phenotype and TF load. RESULTS: Presence of MSCs decreased lag time and increased peak TG. All cell lines demonstrated a dose response to LMWH, with MSC(AT) demonstrating the least thrombogenicity and most sensitivity to LMWH. TG was significantly reduced in all cell lines at doses of 0.2 U/mL LMWH and higher. DISCUSSION: All MSC types and concentrations had a decrease in peak thrombin and TG with increasing amounts of LMWH. While this in vitro study cannot determine optimal dosing, it suggests that LMWH can be effectively used to lower the risk of VTE associated with intravascular administration of MSCs. Future in vivo work can be done to determine optimal dosing and effect on IBMIR and VTE.

Multiyear Follow-up of AAV5-hFVIII-SQ Gene Therapy for Hemophilia A.

BACKGROUND: Adeno-associated virus (AAV)-mediated gene therapy is under investigation as a therapeutic option for persons with hemophilia A. Efficacy and safety data include 3 years of follow-up after a single administration of AAV5-hFVIII-SQ. METHODS: We report durable efficacy, long-term safety, and clinical and biologic results in 15 adults with severe hemophilia A (factor VIII level, ≤1 IU per deciliter) who had received a single infusion of AAV5-hFVIII-SQ at various dose levels. We evaluated the factor VIII level, annualized rate of bleeding events, use of factor VIII, safety, expression kinetics, and biologic markers of AAV transduction for up to 3 years. RESULTS: Three years after infusion, two participants (one who had received 6×1012 vector genomes [vg] per kilogram of body weight and one who had received 2×1013 vg per kilogram) had factor VIII expression of less than 1 IU per deciliter, as assessed on chromogenic assay. Seven participants (who had received 6×1013 vg per kilogram) had a median factor VIII expression of 20 IU per deciliter; the median number of annualized treated bleeding events was 0, and the median use of exogenous factor VIII was reduced from 138.5 infusions to 0 infusions per year. Bleeding in all target joints (major joints with ≥3 bleeding events within 6 months) in this cohort resolved (≤2 bleeding events within 12 months). Two years after infusion, six participants (who had received 4×1013 vg per kilogram) had a median factor VIII expression of 13 IU per deciliter; the median annualized rate of bleeding events was 0, and the median use of factor VIII was reduced from 155.5 infusions to 0.5 infusions per year. Bleeding in target joints resolved in five of six participants. The factor VIII pharmacodynamic profiles reflected cellular turnover in the blood and molecular events leading to episomal DNA stabilization for persistent expression, findings that are consistent with previous observations in two model systems. Transgene-derived human factor VIII (hFVIII) protein activity mirrored native hFVIII in hemostatic ability. No inhibitor development, thromboses, deaths, or persistent changes in liver-function tests were observed. CONCLUSIONS: Gene therapy with AAV5-hFVIII-SQ vector in participants with hemophilia A resulted in sustained, clinically relevant benefit, as measured by a substantial reduction in annualized rates of bleeding events and complete cessation of prophylactic factor VIII use in all participants who had received 4×1013 vg per kilogram or 6×1013 vg per kilogram of the gene therapy. (Funded by BioMarin Pharmaceutical; ClinicalTrials.gov number, NCT02576795; EudraCT number, 2014-003880-38.).

Rurioctocog alfa pegol PK-guided prophylaxis in hemophilia A: results from the phase 3 PROPEL study.

Rurioctocog alfa pegol prophylaxis targeting factor VIII (FVIII) troughs ≥1% has shown to be efficacious with an acceptable safety profile in people with hemophilia A (PwHA). The PROPEL trial compared safety and efficacy of 2 target FVIII troughs in PwHA aged 12 to 65 years, with severe disease, annualized bleeding rate ≥2, and previous FVIII treatment. PwHA were randomized to 12 months' pharmacokinetic (PK)-guided rurioctocog alfa pegol prophylaxis targeting FVIII troughs of 1% to 3% (reference arm) or 8% to 12% (elevated arm); first 6 months was treatment-adjustment period. The primary endpoint was absence of bleeds during the second 6 months, analyzed using multiple imputations (full analysis set [FAS]). In the 1% to 3% and 8% to 12% arms, respectively, point estimates (95% confidence interval) of proportions of PwHA with zero total bleeds were 42% (29% to 55%) and 62% (49% to 75%) in FAS (N = 115; P = .055) and 40% (27% to 55%) and 67% (52% to 81%) in per-protocol analysis set (N = 95; P = .015). Dosing frequency and consumption varied in each arm. Adverse events (AEs) occurred in 70/115 (60.9%) PwHA; serious AEs in 7/115 (6%) PwHA, including 1 treatment-related in 8% to 12% arm (transient anti-FVIII inhibitor). There were no deaths, serious thrombotic events, or AE-related discontinuations. PK-guided prophylaxis was achievable and efficacious in both arms. No new safety signals were observed in the 8% to 12% arm. These results demonstrate elevated FVIII troughs can increase the proportion of PwHA with zero bleeds and emphasize the importance of personalized treatment. This trial was registered at www.clinicaltrials.gov as #NCT02585960.

Factor VII activating protease (FSAP) inhibits the outcome of ischemic stroke in mouse models.

The outcome of ischemic stroke can be improved by further refinements of thrombolysis and reperfusion strategies. Factor VII activating protease (FSAP) is a circulating serine protease that could be important in this context. Its levels are raised in patients as well as mice after stroke and a single nucleotide polymorphism (SNP) in the coding sequence, which results in an inactive enzyme, is linked to an increased risk of stroke. In vitro, FSAP cleaves fibrinogen to promote fibrinolysis, activates protease-activated receptors, and decreases the cellular cytotoxicity of histones. Based on these facts, we hypothesized that FSAP can be used as a treatment for ischemic stroke. A combination of tissue plasminogen activator (tPA), a thrombolytic drug, and recombinant serine protease domain of FSAP (FSAP-SPD) improved regional cerebral perfusion and neurological outcome and reduced infarct size in a mouse model of thromboembolic stroke. FSAP-SPD also improved stroke outcomes and diminished the negative consequences of co-treatment with tPA in the transient middle cerebral artery occlusion model of stroke without altering cerebral perfusion. The inactive MI-isoform of FSAP had no impact in either model. FSAP enhanced the lysis of blood clots in vitro, but in the tail transection model of hemostasis, FSAP-SPD treatment provoked a faster clotting time indicating that it also has pro-coagulant actions. Thus, apart from enhancing thrombolysis, FSAP has multiple effects on stroke progression and represents a promising novel therapeutic strategy in the treatment of ischemic stroke.

Can T-cell and B-cell excision circles predict development of inhibitors in pediatric hemophilia A?

BACKGROUND: Hemophilia A (HA) therapy requires intravenous replacement infusions of factor (F) VIII concentrate. Inhibitors are high-affinity immunoglobulin G that are directed against FVIII and thereby render replacement therapy ineffective. This complication has significant prognostic implications. We aimed to examine the immune system involvement in inhibitor formation specifically T-cell excision circles (TRECs) and B-cell excision circles (KRECs), markers of new T and B cells, respectively, and examine them as surrogate markers for inhibitor formation. METHODS: Blood samples were collected from 35 children with severe HA. Children were divided into two groups: with FVIII inhibitors and without FVIII inhibitors. TRECs and KRECs were measured in peripheral blood. RESULTS: A total of 11 patients with inhibitors and 24 without were evaluated. Children with inhibitors had higher levels of TRECs however not statistically significant (p = 0.085). CjKREC levels were higher in the inhibitor patients (p = 0.003). Moreover, the sj/cjKREC ratio was lower in the inhibitor patients (p = 0.015). CONCLUSIONS: Our findings may add to the notion that inhibitor formation is attributed to humoral immunity due to peripheral B-cell expansion and loss of peripheral tolerance. Improved knowledge regarding the involvement of the immune system in the formation of FVIII inhibitors will enable better therapy tailoring in the era of non-replacement therapies. IMPACT: The etiology of FVIII inhibitor formation is multifactorial, in which the immune system plays a pivotal role. Our findings may add to the notion that inhibitor formation is attributed to humoral immunity due to peripheral B-cell expansion and production of antibodies against FVIII. Improved knowledge regarding the involvement of the immune system in the development of FVIII inhibitors will enable the identification of patients prone to inhibitor development and better therapy tailoring in the new era of non-replacement therapies.

Antibody-Based Ticagrelor Reversal Agent in Healthy Volunteers.

BACKGROUND: Ticagrelor is an oral P2Y12 inhibitor that is used with aspirin to reduce the risk of ischemic events among patients with acute coronary syndromes or previous myocardial infarction. Spontaneous major bleeding and bleeding associated with urgent invasive procedures are concerns with ticagrelor, as with other antiplatelet drugs. The antiplatelet effects of ticagrelor cannot be reversed with platelet transfusion. A rapid-acting reversal agent would be useful. METHODS: In this randomized, double-blind, placebo-controlled, phase 1 trial, we evaluated intravenous PB2452, a monoclonal antibody fragment that binds ticagrelor with high affinity, as a ticagrelor reversal agent. We assessed platelet function in healthy volunteers before and after 48 hours of ticagrelor pretreatment and again after the administration of PB2452 or placebo. Platelet function was assessed with the use of light transmission aggregometry, a point-of-care P2Y12 platelet-reactivity test, and a vasodilator-stimulated phosphoprotein assay. RESULTS: Of the 64 volunteers who underwent randomization, 48 were assigned to receive PB2452 and 16 to receive placebo. After 48 hours of ticagrelor pretreatment, platelet aggregation was suppressed by approximately 80%. PB2452 administered as an initial intravenous bolus followed by a prolonged infusion (8, 12, or 16 hours) was associated with a significantly greater increase in platelet function than placebo, as measured by multiple assays. Ticagrelor reversal occurred within 5 minutes after the initiation of PB2452 and was sustained for more than 20 hours (P<0.001 after Bonferroni adjustment across all time points for all assays). There was no evidence of a rebound in platelet activity after drug cessation. Adverse events related to the trial drug were limited mainly to issues involving the infusion site. CONCLUSIONS: In healthy volunteers, the administration of PB2452, a specific reversal agent for ticagrelor, provided immediate and sustained reversal of the antiplatelet effects of ticagrelor, as measured by multiple assays. (Funded by PhaseBio Pharmaceuticals; ClinicalTrials.gov number, NCT03492385.).

Full Study Report of Andexanet Alfa for Bleeding Associated with Factor Xa Inhibitors.

BACKGROUND: Andexanet alfa is a modified recombinant inactive form of human factor Xa developed for reversal of factor Xa inhibitors. METHODS: We evaluated 352 patients who had acute major bleeding within 18 hours after administration of a factor Xa inhibitor. The patients received a bolus of andexanet, followed by a 2-hour infusion. The coprimary outcomes were the percent change in anti-factor Xa activity after andexanet treatment and the percentage of patients with excellent or good hemostatic efficacy at 12 hours after the end of the infusion, with hemostatic efficacy adjudicated on the basis of prespecified criteria. Efficacy was assessed in the subgroup of patients with confirmed major bleeding and baseline anti-factor Xa activity of at least 75 ng per milliliter (or ≥0.25 IU per milliliter for those receiving enoxaparin). RESULTS: Patients had a mean age of 77 years, and most had substantial cardiovascular disease. Bleeding was predominantly intracranial (in 227 patients [64%]) or gastrointestinal (in 90 patients [26%]). In patients who had received apixaban, the median anti-factor Xa activity decreased from 149.7 ng per milliliter at baseline to 11.1 ng per milliliter after the andexanet bolus (92% reduction; 95% confidence interval [CI], 91 to 93); in patients who had received rivaroxaban, the median value decreased from 211.8 ng per milliliter to 14.2 ng per milliliter (92% reduction; 95% CI, 88 to 94). Excellent or good hemostasis occurred in 204 of 249 patients (82%) who could be evaluated. Within 30 days, death occurred in 49 patients (14%) and a thrombotic event in 34 (10%). Reduction in anti-factor Xa activity was not predictive of hemostatic efficacy overall but was modestly predictive in patients with intracranial hemorrhage. CONCLUSIONS: In patients with acute major bleeding associated with the use of a factor Xa inhibitor, treatment with andexanet markedly reduced anti-factor Xa activity, and 82% of patients had excellent or good hemostatic efficacy at 12 hours, as adjudicated according to prespecified criteria. (Funded by Portola Pharmaceuticals; ANNEXA-4 ClinicalTrials.gov number, NCT02329327.).

A high efficient FVIII variant corrects bleeding in hemophilia A mouse model.

Hemophilia A is a bleeding disorder caused by quantitative or qualitative deficiencies in coagulation factor VIII (FVIII). Low FVIII expression due to its unstable mRNA and binding with immunoglobulin-binding protein (BiP) compromises gene therapy endeavors in hemophilia A. Site-directed mutagenesis have demonstrated an improvement in the expression of FVIII proteins. In this study, a targeted point mutation of Pro at position 290 to Thr (P290T) enhances the in vitro specific activity of B-domain-deleted factor VIII (BDD-FVIII). Hydrodynamic gene delivery of P290T cDNA into FVIII-deficient (FVIII-/-) mice corrected bleeding symptoms. P290T variant resulted in high plasma FVIII coagulant activity 24 h post-gene delivery. Furthermore, bleeding time and average blood loss was significantly reduced in FVIII-/- mice injected with P290T variant, whereas BDD-FVIII and PBS-injected mice experienced prolonged bleeding and excessive blood loss. Histological analysis of the liver biopsies revealed no apparent signs of liver damage. No signs of potential toxicity were seen in mice following mice bodyweights assessment. Altogether, our results demonstrate that the introduction of P290T mutation increases both in vitro and in vivo FVIII coagulant activity, supporting ongoing efforts to develop more effective replacement therapy for hemophilia A.

Prostacyclin analogues decrease platelet aggregation but have no effect on thrombin generation, fibrin clot structure, and fibrinolysis in pulmonary arterial hypertension: PAPAYA coagulation.

Prostacyclin (PGI2) analogues (epoprostenol, treprostonil, iloprost) are the cornerstone of pulmonary arterial hypertension (PAH) treatment. PGI2 analogues inhibit platelet reactivity, but their impact on coagulation and fibrinolysis parameters has not been elucidated. We compared platelet reactivity, thrombin generation, clot permeation, and lysis properties in patients with PAH treated with PGI2 analogues (n = 20) and those not receiving PGI2 analogues (n = 20). Platelet reactivity was lower in patients treated with PGI2 analogues, compared to the control group, as evaluated with arachidonic acid (ASPI), adenosine diphosphate (ADP), and thrombin receptor-activating peptide-6 (TRAP) tests (p = .009, p = .02, p = .007, respectively). In the subgroup analysis, both treprostinil and epoprostenol decreased platelet reactivity to the similar extent. There were no differences regarding thrombin generation, clot permeation, and lysis parameters in patients receiving and not receiving PGI2 analogues (p ≥ .60 for all). In the subgroup analysis, there were no differences regarding coagulation and fibrinolysis parameters between treprostinil, epoprostenol, and no PGI2 analogues. To conclude, patients with PAH treated with PGI2 analogues have reduced platelet reactivity, but similar clot formation and lysis parameters, compared to patients not receiving PGI2 analogues. Further randomized clinical trials are required to confirm these findings.

Andexanet Alfa or Prothrombin Complex Concentrate for Factor Xa Inhibitor Reversal in Acute Major Bleeding: A Systematic Review and Meta-Analysis.

OBJECTIVES: To combine evidence on andexanet alfa and prothrombin complex concentrates for factor Xa inhibitor-associated bleeding to guide clinicians on reversal strategies. DATA SOURCES: Embase, Pubmed, Web of Science, and the Cochrane Library. STUDY SELECTION: Observational studies and randomized clinical trials studying hemostatic effectiveness of andexanet alfa or prothrombin complex concentrate for acute reversal of factor Xa inhibitor-associated hemorrhage. DATA EXTRACTION: Two independent reviewers extracted the data from the studies. Visualization and comparison of hemostatic effectiveness using Sarode et al or International Society of Thrombosis and Hemostasis Scientific and Standardization Committee criteria at 12 and 24 hours, (venous) thrombotic event rates, and inhospital mortality were performed by constructing Forest plots. Exploratory analysis using a logistic mixed model analysis was performed to identify factors associated with effectiveness and venous thromboembolic event. DATA SYNTHESIS: A total of 21 studies were included (andexanet: 438 patients; prothrombin complex concentrate: 1,278 patients). The (weighted) mean effectiveness for andexanet alfa was 82% at 12 hours and 71% at 24 hours. The (weighted) mean effectiveness for prothrombin complex concentrate was 88% at 12 hours and 76% at 24 hours. The mean 30-day symptomatic venous thromboembolic event rates were 5.0% for andexanet alfa and 1.9% for prothrombin complex concentrate. The mean 30-day total thrombotic event rates for andexanet alfa and prothrombin complex concentrate were 10.7% and 3.1%, respectively. Mean inhospital mortality was 23.3% for andexanet versus 15.8% for prothrombin complex concentrate. Exploratory analysis controlling for potential confounders did not demonstrate significant differences between both reversal agents. CONCLUSIONS: Currently, available evidence does not unequivocally support the clinical effectiveness of andexanet alfa or prothrombin complex concentrate to reverse factor Xa inhibitor-associated acute major bleeding, nor does it permit conventional meta-analysis of potential superiority. Neither reversal agent was significantly associated with increased effectiveness or a higher rate of venous thromboembolic event. These results underscore the importance of randomized controlled trials comparing the two reversal agents and may provide guidance in designing institutional guidelines.

New therapies using nonfactor products for patients with hemophilia and inhibitors.

Regular prophylaxis with factor VIII (FVIII) or FIX products to prevent bleeding in patients with severe hemophilia A (HA) and HB, respectively, results in marked suppression of the onset of arthropathy and contributes greatly to improvements in quality of life. Some issues remain with the use of clotting factor replacement therapy, however. The need for multiple IV infusions is associated with a substantial mental and physical burden, and the hemostatic effect of bypassing agents (BPAs) in patients with inhibitor is inconsistent. The development of subcutaneous products with prolonged hemostatic efficiency, irrespective of the presence of inhibitors, has been a longtime wish for patients. A new class of therapeutic agents that act by enhancing coagulation (emicizumab) and inhibiting anticoagulant pathways (fitusiran and concizumab) have been established, and clinical trials using these nonfactor products are ongoing. The current findings have demonstrated that prophylaxis by nonfactor products supports marked reductions of bleeding episodes in hemophilia patients with or without inhibitor. Emicizumab has already been approved for use internationally. Some concerns are evident, however. Thrombotic microangiopathy and thromboembolism have occurred in 5 emicizumab-treated patients receiving repeated infusions of activated prothrombin complex concentrates, and a sinus vein thrombosis has occurred in a fitusiran-treated patient receiving repeated infusions of FVIII product. Moreover, reliable techniques to monitor hemostatic function in patients receiving nonfactor products with concomitant BPA or FVIII/FIX therapies require further assessment. These novel therapeutic agents have promising hemostatic properties, although wider experience in hemophilia centers is warranted to establish appropriate therapeutic strategies.

Treatment of rare factor deficiencies other than hemophilia.

The deficiency of fibrinogen, prothrombin, factor V (FV), FVII, FVIII, FIX, FX, FXI, and FXIII, called rare coagulation disorders (RCDs), may result in coagulopathies leading to spontaneous or posttrauma and postsurgery hemorrhages. RCDs are characterized by a wide variety of symptoms, from mild to severe, which can vary significantly from 1 disease to another and from 1 patient to another. The most typical symptoms of all RCDs are mucosal bleedings and bleeding at the time of invasive procedures, whereas other life-threatening symptoms such as central nervous system bleeding and hemarthroses are mostly present only in some deficiencies (afibrinogenemia, FX, and FXIII). At variance with hemophilia A and B and von Willebrand disease, RCDs are much less prevalent, ranging from 1 case in 500 000 to 1 in 2 million in the general population. Their clinical heterogeneity associated with the low number of patients has led to a delay in the development of appropriate therapies. Indeed, a similar heterogeneity can also be found in the treatment products available, ranging from the specific recombinant proteins to treat FVII- and FXIII-deficient patients to the complete absence of specific products to treat patients with FII or FV deficiencies, for whom prothrombin complex concentrates or fresh frozen plasma are, to date, the only option. The recent development of novel hemostatic approaches for hemophilia, such as the use of nonsubstitutive therapy as RNA interference, anti-tissue factor pathway inhibitor, and the gene therapy aimed at improving the patient's quality of life may also have an important role in the treatment of patients with RCDs in the future.

New therapies for hemophilia.

Hemophilia A (HA) and hemophilia B (HB) are the most common severe bleeding disorders. Replacement therapy, providing the missing coagulation factor, has been the mainstay of treatment both prophylactically and to treat bleeding. Despite widespread availability of safe and effective replacement therapy, patients with HA and HB continue to experience a tremendous burden of treatment, breakthrough bleeding, and progressive joint disease, as well as high rates of inhibitor development. These remaining challenges are now being addressed by incredible advances in bioengineering. Recombinant bioengineering has led to replacement therapies with easier modes of administration, decreased immunogenicity, increased efficacy, and extended half-lives. Emicizumab, a bispecific antibody that acts as a substitutive therapy for HA, has been approved for patients with and without inhibitors. Novel compounds are in development to exploit the natural balance of hemostasis by targeting the natural anticoagulants protein C, protein S, tissue factor pathway inhibitor, and antithrombin. The substitution and rebalancing therapies provide an opportunity for steady-state hemostatic control without exposure to immunogenic clotting factor proteins. As such, they may have broader applications outside those being investigated in the clinical trial programs.

Choosing the Best Approach to Warfarin Reversal After Traumatic Intracranial Hemorrhage.

BACKGROUND: Patients on warfarin with traumatic intracranial hemorrhage often have the warfarin effects pharmacologically reversed. We compared outcomes among patients who received 4-factor prothrombin complex concentrate (PCC), fresh frozen plasma (FFP), or no reversal to assess the real-world impact of PCC on elderly patients with traumatic intracranial hemorrhage (ICH). MATERIALS AND METHODS: This was a retrospective analysis of 150 patients on preinjury warfarin. Data were manually abstracted from the electronic medical record of an academic level 1 trauma center for patients admitted between January 2013 and December 2018. Outcomes were ICH progression on follow-up computed tomography scan, mortality, need for surgical intervention, and trends in the use of reversal agents. RESULTS: Of 150 patients eligible for analysis, 41 received FFP, 60 PCC, and 49 were not reversed. On multivariable analysis, patients not reversed [OR 0.25 95% CI (0.31-0.85)] and women [OR 0.38 95% CI (0.17-0.88)] were less likely to experience progression of their initial bleed on follow-up computed tomography while subdural hemorrhage increased the risk [OR 3.69 95% CI (1.27-10.73)]. There was no difference between groups in terms of mortality or need for surgery. Over time use of reversal with PCC increased while use of FFP and not reversing warfarin declined (P < 0.001). CONCLUSIONS: Male gender and using a reversal agent were associated with progression of ICH. Choice of reversal did not impact the need for surgery, hospital length of stay, or mortality. Some ICH patients may not require warfarin reversal and may bias studies, especially retrospective studies of warfarin reversal.

Novel treatments for hemophilia through rebalancing of the coagulation cascade.

Hemophilia A and B are inherited hemorrhagic disorders that result from alterations in the coagulation cascade. Aside from spontaneous bleeding, the main complication of hemophilia is hemarthrosis. Progress over the last three decades, specifically prophylaxis using recombinant factor, has prevented hemarthrosis and lengthened patient life expectancies. However, many treatments require frequent dosing up to three times a week, and alloantibodies (inhibitors) against replacement factor continues to be an issue. These problems call for novel treatments for patients with hemophilia. Although there has been progress in extended half-life factors and mimetics of factor VIII, an alternative treatment methodology is to rebalance the activities of pro- and anticoagulant factors through inhibition of the natural anticoagulants: antithrombin, tissue factor pathway inhibitor, protein C, and protein S. This review will explore the efficacy of targeting these inhibitory pathways from preclinical development through clinical trials, and delve into concerns of thrombotic risk.

Pro-coagulant imbalance in patients with community acquired pneumonia assessed on admission and one month after hospital discharge.

OBJECTIVES: Patients hospitalized because of community-acquired-pneumonia (CAP) are at risk of cardiovascular diseases. Although plasma procoagulant imbalance play a role, mechanisms are not completely understood. We aimed to investigate whether there is a measurable state of procoagulant imbalance following inflammation determined by CAP. METHODS: We analyzed blood from 51 CAP patients at admission and 51 healthy subjects (HS) for (i) pro and anticoagulants, (ii) thrombin generation (TG) with or without thrombomodulin (TM), which is the physiologic activator of the protein C anticoagulant pathway and(iii) by assessing the ratio between von Willebrand-factor (VWF) and its protease ADAMTS13. Thirty patients were re-analyzed one month after discharge when CAP was resolved. RESULTS: Median levels of TG parameters, including the endogenous thrombin potential (ETP), the ETP-TM-ratio (with/without TM), peak-thrombin and velocity index were higher in patients at baseline than HS. In particular, the median (IQR) ETP-TM-ratio in patients vs. HS was 0.88 (0.83-0.91) vs. 0.63 (0.48-0.71), p<0.001. Factor (F)VIII, a potent procoagulant involved in TG was higher in patients at baseline than HS [195 U/dL (100-388) vs. 127(108-145)], p<0.001]. The ratio of VWF/ADAMTS13 was higher at baseline than HS. Cumulatively, the findings indicate a state of pro-coagulant imbalance, which (although reduced), remained high [i.e., ETP-TM-ratio, 0.80 (0.74-0.84); FVIII, 152 U/dL (122-190)] one month after discharge when the infection was resolved. CONCLUSIONS: Patients with CAP possess a state of pro-coagulant imbalance, which remains substantially high, even when the infection is resolved. The findings suggest CAP patients as candidates for antithrombotic prophylaxis even after the resolution of infection. Clinical trials are warranted to assess the benefit/risk ratio of prophylaxis extension.

Generation of hyperfunctional recombinant human factor IX variants expressed in human cell line SK-Hep-1.

OBJECTIVE: To develop recombinant factor IX (FIX) variants with augmented clotting activity. RESULTS: We generated three new variants, FIX-YKALW, FIX-ALL and FIX-LLW, expressed in SK-Hep-1 cells and characterized in vitro and in vivo. FIX-YKALW showed the highest antigen expression level among the variants (2.17 µg-mL), followed by FIX-LLW (1.5 µg-mL) and FIX-ALL (0.9 µg-mL). The expression level of FIX variants was two-five fold lower than FIX-wild-type (FIX-WT) (4.37 µg-mL). However, the biological activities of FIX variants were 15-31 times greater than FIX-WT in the chromogenic assay. Moreover, the new variants FIX-YKALW, FIX-LLW and FIX-ALL also presented higher specific activity than FIX-WT (17, 20 and 29-fold higher, respectively). FIX variants demonstrated a better clotting time than FIX-WT. In hemophilia B mice, we observed that FIX-YKALW promoted hemostatic protection. CONCLUSION: We have developed three improved FIX proteins with potential for use in protein replacement therapy for hemophilia B.

Fibrinogen Replacement Therapy for Traumatic Coagulopathy: Does the Fibrinogen Source Matter?

Fibrinogen is the first coagulation protein to reach critically low levels during traumatic haemorrhage. There have been no differential effects on clinical outcomes between the two main sources of fibrinogen replacement: cryoprecipitate and fibrinogen concentrate (Fg-C). However, the constituents of these sources are very different. The aim of this study was to determine whether these give rise to any differences in clot stability that may occur during trauma haemorrhage. Fibrinogen deficient plasma (FDP) was spiked with fibrinogen from cryoprecipitate or Fg-C. A panel of coagulation factors, rotational thromboelastography (ROTEM), thrombin generation (TG), clot lysis and confocal microscopy were performed to measure clot strength and stability. Increasing concentrations of fibrinogen from Fg-C or cryoprecipitate added to FDP strongly correlated with Clauss fibrinogen, demonstrating good recovery of fibrinogen (r2 = 0.99). A marked increase in Factor VIII, XIII and α2-antiplasmin was observed in cryoprecipitate (p < 0.05). Increasing concentrations of fibrinogen from both sources were strongly correlated with ROTEM parameters (r2 = 0.78-0.98). Cryoprecipitate therapy improved TG potential, increased fibrinolytic resistance and formed more homogeneous fibrin clots, compared to Fg-C. In summary, our data indicate that cryoprecipitate may be a superior source of fibrinogen to successfully control bleeding in trauma coagulopathy. However, these different products require evaluation in a clinical setting.

Management of Intracranial Hemorrhage in Patients with a Left Ventricular Assist Device: A Systematic Review and Meta-Analysis.

BACKGROUND: Intracranial hemorrhage (ICH) has been reported to occur in up to 23% of patients with left ventricular assist devices (LVADs). Currently, limited data exists to guide neurosurgical management strategies to optimize outcomes in patients with an LVAD who develop ICH. METHODS: A systematic review and meta-analysis of the literature was performed to evaluate the mortality rate in these patients following medical and/or surgical management and to evaluate antithrombotic reversal and resumption strategies after hemorrhage. RESULTS: 17 studies reporting on 3869 LVAD patients and 545 intracranial hemorrhages spanning investigative periods from 1996 to 2019 were included. The rate of ICH in LVAD patients was 10.6% (411/3869) with 58.6% (231/394) being intraparenchymal hemorrhage (IPH), 23.6% (93/394) subarachnoid hemorrhage (SAH), and 15.5% (61/394) subdural hemorrhage (SDH). Total mortality rates for surgical management 65.6% (40/61) differed from medical management at 45.2% (109/241). There was an increased relative risk of mortality (RR=1.45, 95% CI: 1.10-1.91, p = 0.01) for ICH patients undergoing surgical intervention. The hemorrhage subtype most frequently managed with anticoagulation reversal was IPH 81.8% (63/77), followed by SDH 52.2% (12/23), and SAH 39.1% (18/46). Mean number of days until antithrombotic resumption ranged from 6 to 10.5 days. CONCLUSION: Outcomes remain poor, specifically for those undergoing surgery. As experience with this population increases, prospective studies are warranted to contribute to management and prognostication .