Oral Anticoagulants Beyond Warfarin.

Direct oral anticoagulants (DOACs) have largely replaced vitamin K antagonists, mostly warfarin, for the main indications for oral anticoagulation, prevention and treatment of venous thromboembolism, and prevention of embolic stroke in atrial fibrillation. While DOACs offer practical, fixed-dose anticoagulation in many patients, specific restrictions or contraindications may apply. DOACs are not sufficiently effective in high-thrombotic risk conditions such as antiphospholipid syndrome and mechanical heart valves. Patients with cancer-associated thrombosis may benefit from DOACs, but the bleeding risk, particularly in those with gastrointestinal or urogenital tumors, must be carefully weighed. In patients with frailty, excess body weight, and/or moderate-to-severe chronic kidney disease, DOACs must be cautiously administered and may require laboratory monitoring. Reversal agents have been developed and approved for life-threatening bleeding. In addition, the clinical testing of potentially safer anticoagulants such as factor XI(a) inhibitors is important to further optimize anticoagulant therapy in an increasingly elderly and frail population worldwide.

An architecturally rational hemostat for rapid stopping of massive bleeding on anticoagulation therapy.

Hemostatic devices are critical for managing emergent severe bleeding. With the increased use of anticoagulant therapy, there is a need for next-generation hemostats. We rationalized that a hemostat with an architecture designed to increase contact with blood, and engineered from a material that activates a distinct and undrugged coagulation pathway can address the emerging need. Inspired by lung alveolar architecture, here, we describe the engineering of a next-generation single-phase chitosan hemostat with a tortuous spherical microporous design that enables rapid blood absorption and concentrated platelets and fibrin microthrombi in localized regions, a phenomenon less observed with other classical hemostats without structural optimization. The interaction between blood components and the porous hemostat was further amplified based on the charged surface of chitosan. Contrary to the dogma that chitosan does not directly affect physiological clotting mechanism, the hemostat induced coagulation via a direct activation of platelet Toll-like receptor 2. Our engineered porous hemostat effectively stopped the bleeding from murine liver wounds, swine liver and carotid artery injuries, and the human radial artery puncture site within a few minutes with significantly reduced blood loss, even under the anticoagulant treatment. The integration of engineering design principles with an understanding of the molecular mechanisms can lead to hemostats with improved functions to address emerging medical needs.

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.).

Emicizumab prophylaxis in infants with hemophilia A (HAVEN 7): primary analysis of a phase 3b open-label trial.

ABSTRACT: Subcutaneous emicizumab enables prophylaxis for people with hemophilia A (HA) from birth, potentially reducing risk of bleeding and intracranial hemorrhage (ICH). HAVEN 7 (NCT04431726) is the first clinical trial of emicizumab dedicated to infants, designed to investigate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab in those aged ≤12 months with severe HA without factor VIII (FVIII) inhibitors. Participants in this phase 3b trial received emicizumab 3 mg/kg maintenance dose every 2 weeks for 52 weeks and are continuing emicizumab during the 7-year long-term follow-up. Efficacy end points included annualized bleed rate (ABR): treated, all, treated spontaneous, and treated joint bleeds. Safety end points included adverse events (AEs), thromboembolic events (TEs), thrombotic microangiopathies (TMAs), and immunogenicity (anti-emicizumab antibodies [ADAs] and FVIII inhibitors). At primary analysis, 55 male participants had received emicizumab (median treatment duration: 100.3; range, 52-118 weeks). Median age at informed consent was 4.0 months (range, 9 days to 11 months 30 days). Model-based ABR for treated bleeds was 0.4 (95% confidence interval, 0.30-0.63), with 54.5% of participants (n = 30) having zero treated bleeds. No ICH occurred. All 42 treated bleeds in 25 participants (45.5%) were traumatic. Nine participants (16.4%) had ≥1 emicizumab-related AE (all grade 1 injection-site reactions). No AE led to treatment changes. No deaths, TEs, or TMAs occurred. No participant tested positive for ADAs. Two participants were confirmed positive for FVIII inhibitors. This primary analysis of HAVEN 7 indicates that emicizumab is efficacious and well tolerated in infants with severe HA without FVIII inhibitors.

Postprocedural Anticoagulation After Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction: A Multicenter, Randomized, Double-Blind Trial.

BACKGROUND: Postprocedural anticoagulation (PPA) is frequently administered after primary percutaneous coronary intervention in ST-segment-elevation myocardial infarction, although no conclusive data support this practice. METHODS: The RIGHT trial (Comparison of Anticoagulation Prolongation vs no Anticoagulation in STEMI Patients After Primary PCI) was an investigator-initiated, multicenter, randomized, double-blind, placebo-controlled, superiority trial conducted at 53 centers in China. Patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention were randomly assigned by center to receive low-dose PPA or matching placebo for at least 48 hours. Before trial initiation, each center selected 1 of 3 PPA regimens (40 mg of enoxaparin once daily subcutaneously; 10 U·kg·h of unfractionated heparin intravenously, adjusted to maintain activated clotting time between 150 and 220 seconds; or 0.2 mg·kg·h of bivalirudin intravenously). The primary efficacy objective was to demonstrate superiority of PPA to reduce the primary efficacy end point of all-cause death, nonfatal myocardial infarction, nonfatal stroke, stent thrombosis (definite), or urgent revascularization (any vessel) within 30 days. The key secondary objective was to evaluate the effect of each specific anticoagulation regimen (enoxaparin, unfractionated heparin, or bivalirudin) on the primary efficacy end point. The primary safety end point was Bleeding Academic Research Consortium 3 to 5 bleeding at 30 days. RESULTS: Between January 10, 2019, and September 18, 2021, a total of 2989 patients were randomized. The primary efficacy end point occurred in 37 patients (2.5%) in both the PPA and placebo groups (hazard ratio, 1.00 [95% CI, 0.63 to 1.57]). The incidence of Bleeding Academic Research Consortium 3 to 5 bleeding did not differ between the PPA and placebo groups (8 [0.5%] vs 11 [0.7%] patients; hazard ratio, 0.74 [95% CI, 0.30 to 1.83]). CONCLUSIONS: Routine PPA after primary percutaneous coronary intervention was safe but did not reduce 30-day ischemic events. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03664180.

Targeted prophylactic anticoagulation based on the TRiP(cast) score in patients with lower limb immobilisation: a multicentre, stepped wedge, randomised implementation trial.

BACKGROUND: Prophylactic anticoagulation in emergency department patients with lower limb trauma requiring immobilisation is controversial. The Thrombosis Risk Prediction for Patients with Cast Immobilisation-TRiP(cast)-score could identify a large subgroup of patients at low risk of venous thromboembolism for whom prophylactic anticoagulation can be safely withheld. We aimed to prospectively assess the safety of withholding anticoagulation for patients with lower limb trauma at low risk of venous thromboembolism, defined by a TRiP(cast) score of less than 7. METHODS: CASTING was a stepped-wedge, multicentre, cluster-randomised trial with blinded outcome assessment. 15 emergency departments in France and Belgium were selected and randomly assigned staggered start dates for switching from the control phase (ie, anticoagulation prescription according to the physician's usual practice) to the intervention phase (ie, targeted anticoagulation according to TRiP(cast) score: no prescription if score <7 and anticoagulation if score was ≥7). Patients were included if they presented to a participating emergency department with lower limb trauma requiring immobilisation for at least 7 days and were aged 18 years or older. The primary outcome was the 3-month cumulative rate of symptomatic venous thromboembolism during the intervention phase in patients with a TRiP(cast) score of less than 7. The targeted strategy was considered safe if this rate was less than 1% with an upper 95% CI of less than 2%. The primary analysis was performed in the intention-to-treat population. This study is registered at ClinicalTrials.gov (NCT04064489). FINDINGS: Between June 16, 2020, and Sept 15, 2021, 15 clusters and 2120 patients were included. Of the 1505 patients analysed in the intervention phase, 1159 (77·0%) had a TRiP(cast) score of less than 7 and did not receive anticoagulant treatment. The symptomatic venous thromboembolism rate was 0·7% (95% CI 0·3-1·4, n=8/1159). There was no difference between the control and the intervention phases in the cumulative rate of symptomatic venous thromboembolism or in bleeding rates. INTERPRETATION: Patients with a TRiP(cast) score of less than 7 who are not receiving anticoagulation have a very low risk of venous thromboembolism. A large proportion of patients with lower limb trauma and immobilisation could safely avoid thromboprophylaxis. FUNDING: French Ministry of Health.

Innovations in RNA therapy for hemophilia.

Given the shortcomings of current factor-, nonfactor-, and adeno-associated virus gene-based therapies, the recent advent of RNA-based therapeutics for hemophilia is changing the fundamental approach to hemophilia management. From small interfering RNA therapeutics that knockdown clot regulators antithrombin, protein S, and heparin cofactor II, to CRISPR/Cas9 gene editing that may personalize treatment, improved technologies have the potential to reduce bleeds and factor use and avoid inhibitor formation. These novel agents, some in preclinical studies and others in early phase trials, have the potential to simplify treatment and improve hemostasis and quality of life. Furthermore, because these therapies arise from manipulation of the coagulation cascade and thrombin generation and its regulation, they will enhance our understanding of hemostasis and thrombosis and ultimately lead to better therapies for children and adults with inherited bleeding disorders. What does the future hold? With the development of novel preclinical technologies at the bench, there will be fewer joint bleeds, debilitating joint disease, orthopedic surgery, and improved physical and mental health, which were not previously possible. In this review, we identify current limitations of treatment and progress in the development of novel RNA therapeutics, including messenger RNA nanoparticle delivery and gene editing for the treatment of hemophilia.

Final Study Report of Andexanet Alfa for Major Bleeding With Factor Xa Inhibitors.

BACKGROUND: Andexanet alfa is a modified recombinant inactive factor Xa (FXa) designed to reverse FXa inhibitors. ANNEXA-4 (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of Factor Xa Inhibitors) was a multicenter, prospective, phase-3b/4, single-group cohort study that evaluated andexanet alfa in patients with acute major bleeding. The results of the final analyses are presented. METHODS: Patients with acute major bleeding within 18 hours of FXa inhibitor administration were enrolled. Co-primary end points were anti-FXa activity change from baseline during andexanet alfa treatment and excellent or good hemostatic efficacy, defined by a scale used in previous reversal studies, at 12 hours. The efficacy population included patients with baseline anti-FXa activity levels above predefined thresholds (≥75 ng/mL for apixaban and rivaroxaban, ≥40 ng/mL for edoxaban, and ≥0.25 IU/mL for enoxaparin; reported in the same units used for calibrators) who were adjudicated as meeting major bleeding criteria (modified International Society on Thrombosis and Haemostasis definition). The safety population included all patients. Major bleeding criteria, hemostatic efficacy, thrombotic events (stratified by occurring before or after restart of either prophylactic [ie, a lower dose, for prevention rather than treatment] or full-dose oral anticoagulation), and deaths were assessed by an independent adjudication committee. Median endogenous thrombin potential at baseline and across the follow-up period was a secondary outcome. RESULTS: There were 479 patients enrolled (mean age, 78 years; 54% male; 86% White); 81% were anticoagulated for atrial fibrillation, and the median time was 11.4 hours since last dose, with 245 (51%) on apixaban, 176 (37%) on rivaroxaban, 36 (8%) on edoxaban, and 22 (5%) on enoxaparin. Bleeding was predominantly intracranial (n=331 [69%]) or gastrointestinal (n=109 [23%]). In evaluable apixaban patients (n=172), median anti-FXa activity decreased from 146.9 ng/mL to 10.0 ng/mL (reduction, 93% [95% CI, 94-93]); in rivaroxaban patients (n=132), it decreased from 214.6 ng/mL to 10.8 ng/mL (94% [95% CI, 95-93]); in edoxaban patients (n=28), it decreased from 121.1 ng/mL to 24.4 ng/mL (71% [95% CI, 82-65); and in enoxaparin patients (n=17), it decreased from 0.48 IU/mL to 0.11 IU/mL (75% [95% CI, 79-67]). Excellent or good hemostasis occurred in 274 of 342 evaluable patients (80% [95% CI, 75-84]). In the safety population, thrombotic events occurred in 50 (10%) patients; in 16 patients, these occurred during treatment with prophylactic anticoagulation that began after the bleeding event. No thrombotic episodes occurred after oral anticoagulation restart. Specific to certain populations, reduction of anti-FXa activity from baseline to nadir significantly predicted hemostatic efficacy in patients with intracranial hemorrhage (area under the receiver operating characteristic curve, 0.62 [95% CI, 0.54-0.70]) and correlated with lower mortality in patients <75 years of age (adjusted P=0.022; unadjusted P=0.003). Median endogenous thrombin potential was within the normal range by the end of andexanet alfa bolus through 24 hours for all FXa inhibitors. CONCLUSIONS: In patients with major bleeding associated with the use of FXa inhibitors, treatment with andexanet alfa reduced anti-FXa activity and was associated with good or excellent hemostatic efficacy in 80% of patients. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02329327.

Rivaroxaban for Prevention of Thrombotic Events, Hospitalization, and Death in Outpatients With COVID-19: A Randomized Clinical Trial.

BACKGROUND: COVID-19 (coronavirus disease 2019) is associated with heightened risks of venous and arterial thrombosis and hospitalization due to respiratory failure. To assess whether prophylactic anticoagulation can safely reduce the frequency of venous and arterial thrombosis, hospitalization, and death in nonhospitalized patients with symptomatic COVID-19 and at least one thrombosis risk factor, we conducted the PREVENT-HD double-blind, placebo-controlled randomized trial (A Study of Rivaroxaban to Reduce the Risk of Major Venous and Arterial Thrombotic Events, Hospitalization and Death in Medically Ill Outpatients With Acute, Symptomatic COVID-19] Infection). METHODS: PREVENT-HD was conducted between August 2020 and April 2022 at 14 US integrated health care delivery networks. A virtual trial design used remote informed consent and clinical monitoring and facilitated data collection through electronic health record integration with a cloud-based research platform. Nonhospitalized patients with symptomatic COVID-19 and at least one thrombosis risk factor were enrolled and randomly assigned to either 10 mg of oral rivaroxaban or placebo daily for 35 days. The primary efficacy outcome was time to first occurrence of a composite of symptomatic venous thromboembolism, myocardial infarction, ischemic stroke, acute limb ischemia, non-central nervous system systemic arterial embolism, hospitalization, or death through day 35. The principal safety end point was International Society on Thrombosis and Hemostasis critical-site or fatal bleeding. The last study visit was on day 49. RESULTS: The study was terminated prematurely because of enrollment challenges and a lower-than-expected blinded pooled event rate. A total of 1284 patients underwent randomization with complete accrual of primary events through May 2022. No patients were lost to follow-up. The primary efficacy outcome occurred in 22 of 641 in the rivaroxaban group and 19 of 643 in the placebo group (3.4% versus 3.0%; hazard ratio, 1.16 [95% CI, 0.63-2.15]; P=0.63). No patient in either group experienced critical-site or fatal bleeding. One patient receiving rivaroxaban had a major bleed. CONCLUSIONS: The study was terminated prematurely after enrollment of 32% of planned accrual because of recruitment challenges and lower-than-expected event rate. Rivaroxaban prescribed for 35 days in nonhospitalized patients with symptomatic COVID-19 at risk for thrombosis did not appear to reduce a composite end point of venous and arterial thrombotic events, hospitalization, and death. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT04508023.

Aspirin Versus Clopidogrel for Long-Term Maintenance Monotherapy After Percutaneous Coronary Intervention: The HOST-EXAM Extended Study.

BACKGROUND: Long-term outcomes of antiplatelet monotherapy in patients who receive percutaneous coronary intervention are unknown. The HOST-EXAM (Harmonizing Optimal Strategy for Treatment of Coronary Artery Stenosis-Extended Antiplatelet Monotherapy) Extended study reports the posttrial follow-up results of the original HOST-EXAM trial. METHODS: From March 2014 through May 2018, 5438 patients who maintained dual antiplatelet therapy without clinical events for 12±6 months after percutaneous coronary intervention with drug-eluting stents were randomly assigned in a 1:1 ratio to receive clopidogrel (75 mg once daily) or aspirin (100 mg once daily). The primary end point (a composite of all-cause death, nonfatal myocardial infarction, stroke, readmission attributable to acute coronary syndrome, and Bleeding Academic Research Consortium type 3 or greater bleeding), secondary thrombotic end point (cardiac death, nonfatal myocardial infarction, ischemic stroke, readmission attributable to acute coronary syndrome, and definite or probable stent thrombosis), and bleeding end point (Bleeding Academic Research Consortium type 2 or greater bleeding) were analyzed during the extended follow-up period. Analysis was performed on the per-protocol population (2431 patients in the clopidogrel group and 2286 patients in the aspirin group). RESULTS: During a median follow-up of 5.8 years (interquartile range, 4.8-6.2 years), the primary end point occurred in 12.8% and 16.9% in the clopidogrel and aspirin groups, respectively (hazard ratio, 0.74 [95% CI, 0.63-0.86]; P<0.001). The clopidogrel group had a lower risk for the secondary thrombotic end point (7.9% versus 11.9%; hazard ratio, 0.66 [95% CI, 0.55-0.79]; P<0.001) and secondary bleeding end point (4.5% versus 6.1%; hazard ratio, 0.74 [95% CI, 0.57-0.94]; P=0.016). There was no significant difference in the incidence of all-cause death between the 2 groups (6.2% versus 6.0%; hazard ratio, 1.04 [95% CI, 0.82-1.31]; P=0.742). Landmark analysis at 2 years showed that the beneficial effect of clopidogrel was consistent throughout the follow-up period. CONCLUSIONS: During an extended follow-up of >5 years after randomization, clopidogrel monotherapy compared with aspirin monotherapy was associated with lower rates of the composite net clinical outcome in patients without clinical events for 12±6 months after percutaneous coronary intervention with drug-eluting stents. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02044250.

Comparative Effectiveness and Safety of Direct Oral Anticoagulants and Warfarin in Patients With Atrial Fibrillation and Chronic Liver Disease: A Nationwide Cohort Study.

BACKGROUND: The benefit-risk profile of direct oral anticoagulants (DOACs) compared with warfarin, and between DOACs in patients with atrial fibrillation (AF) and chronic liver disease is unclear. METHODS: We conducted a new-user, retrospective cohort study of patients with AF and chronic liver disease who were enrolled in a large, US-based administrative database between January 1, 2011, and December 31, 2017. We assessed the effectiveness and safety of DOACs (as a class and individually) compared with warfarin, and between DOACs in patients with AF and chronic liver disease. The primary outcomes were hospitalization for ischemic stroke/systemic embolism and hospitalization for major bleeding. Inverse probability treatment weights were used to balance the treatment groups on measured confounders. RESULTS: Overall, 10 209 participants were included, with 4421 (43.2%) on warfarin, 2721 (26.7%) apixaban, 2211 (21.7%) rivaroxaban, and 851 (8.3%) dabigatran. The incidence rates per 100 person-years for ischemic stroke/systemic embolism were 2.2, 1.4, 2.6, and 4.4 for DOACs as a class, apixaban, rivaroxaban, and warfarin, respectively. The incidence rates per 100 person-years for major bleeding were 7.9, 6.5, 9.1, and 15.0 for DOACs as a class, apixaban, rivaroxaban, and warfarin, respectively. After inverse probability treatment weights, the risk of hospitalization for ischemic stroke/systemic embolism was significantly lower between DOACs as a class (hazard ratio [HR], 0.64 [95% CI, 0.46-0.90]) or apixaban (HR, 0.40 [95% CI, 0.19-0.82]) compared with warfarin, but not significantly different between rivaroxaban versus warfarin (HR, 0.76 [95% CI, 0.47-1.21]) or rivaroxaban versus apixaban (HR, 1.73 [95% CI, 0.91-3.29]). Compared with warfarin, the risk of hospitalization for major bleeding was lower with DOACs as a class (HR, 0.69 [95% CI, 0.58-0.82]), apixaban (HR, 0.60 [95% CI, 0.46-0.78]), and rivaroxaban (HR, 0.79 [95% CI, 0.62-1.0]). However, the risk of hospitalization for major bleeding was higher for rivaroxaban versus apixaban (HR, 1.59 [95% CI, 1.18-2.14]). CONCLUSIONS: Among patients with AF and chronic liver disease, DOACs as a class were associated with lower risks of hospitalization for ischemic stroke/systemic embolism and major bleeding versus warfarin. However, the incidence of clinical outcomes among patients with AF and chronic liver disease varied between individual DOACs and warfarin, and in head-to-head DOAC comparisons.

Emicizumab prophylaxis in infants: Single-centre experience.

The hallmark of haemophilia A (HA) therapy is prophylaxis, aimed at spontaneous bleeding prevention. Emicizumab provides a viable alternative to intravenous factor replacement therapy. However, data on its use in infants are limited. This single-centre open arm prospective study reports on emicizumab prophylaxis in infants. We included severe HA patients under 1 year who started emicizumab prophylaxis since 2018, with longitudinal follow-up. The study collected data on demographics, clinical and laboratory variables, the occurrence of bleeding events, surgeries and treatment outcomes. Of the 27 enrolled infants, whose median age at prophylaxis initiation was 7 months, 24 primarily choose to start emicizumab therapy (3/27 switched from FVIII prophylaxis due to development of FVIII inhibitors). The median age for prophylaxis initiation decreased to 3 months in 2023. Following emicizumab initiation, the median calculated ABR decreased, and no intracranial haemorrhages were observed. Thrombin generation showed a significant improvement in peak height and endogenous thrombin potential at steady state after a loading period. Our study highlights a shift towards early prophylaxis in the era of non-replacement therapies. It underscores the need for continuous evaluation and refinement of treatment approaches, emphasizing personalized care and diligent monitoring in the evolving field of paediatric haemophilia care.

Fixed- Versus Variable-Dose Prothrombin Complex Concentrate for the Emergent Reversal of Vitamin K Antagonists: A Systematic Review and Meta-Analysis.

OBJECTIVES: Four-factor prothrombin complex concentrate (4-PCC) is recommended for rapid reversal of vitamin K antagonists (VKAs) such as warfarin, yet optimal dosing remains uncertain. DATA SOURCES: A systematic review was conducted of PubMed, Embase, and Ovid MEDLINE (Wolters Kluwer) databases from January 2000 to August 2023 for clinical studies comparing fixed- vs. variable-dose 4-PCC for emergent VKA reversal with at least one reported clinical outcome. STUDY SELECTION: Abstracts and full texts were assessed independently and in duplicate by two reviewers. DATA EXTRACTION: Data were extracted independently and in duplicate by two reviewers using predefined extraction forms. DATA SYNTHESIS: The analysis comprised three randomized trials and 16 cohort studies comprising a total of 323 participants in randomized trials (161 in fixed dosage and 162 in variable dosage) and 1912 patients in cohort studies (858 in fixed-dose and 1054 in variable dose). Extracranial bleeding was the predominant indication, while intracranial hemorrhage varied. Overall, a fixed-dose regimen may be associated with a lower dose of 4-PCC and results in a reduction in 4-PCC administration time compared with a variable-dose regimen. A fixed-dose regimen also likely results in increased clinical hemostasis. While there is no clear difference between the two regimens in terms of achieving a goal international normalized ratio (INR) less than 2, a fixed-dose regimen is less likely to achieve a goal INR less than 1.5. High certainty evidence indicates that the fixed-dose regimen reduces both mortality and the occurrence of thromboembolic events. Additional subgroup analyses provides exploratory data to guide future studies. CONCLUSIONS: A fixed-dose regimen for 4-PCC administration provides benefits over a variable-dose regimen in terms of dose reduction, faster administration time, improved clinical hemostasis, and reduced mortality and thromboembolic events. Further studies are warranted to better refine the optimal fixed-dose regimen.

Combined immunosuppression for acquired hemophilia A: CyDRi is a highly effective low-toxicity regimen.

Acquired hemophilia A (AHA) is a rare severe autoimmune bleeding disorder with significant morbidity and mortality. Although critical for disease control, there is no consensus for the best immunosuppressive regimen. Most authors use steroids first line, followed by other agents for steroid failures. Upfront combined regimens offer the advantage of reduced steroid exposure and toxicity as well as increased efficacy. We retrospectively analyzed data from 32 patients with AHA treated on an identical such institutional protocol: cyclophosphamide 1000 mg on days 1 and 22, dexamethasone 40 mg on days 1, 8, 15, and 22, and rituximab 100 mg on days 1, 8, 15, and 22 (the regimen was termed CyDRi). All patients received at least 1 cycle of CyDRi. If necessary, CyDRi was repeated until remission, no sooner than day 43 of the previous cycle. Bleeding control was rapidly achieved. The median time for bleeding control was 15.5 days (range, 0-429 days; interquartile range, 2.5-29.5 days). Thirty-one (96.8%) of 32 patients achieved durable complete remission (CR); 29 (90.6%) of 32 patients were alive at last follow-up, all of them in CR. The median time to reach first CR was 77 days (range, 19-939 days; interquartile range, 31-115 days). Toxicity and side effects were acceptable and milder than those of commonly used, prolonged steroid therapies. In conclusion, the CyDRi regimen produced markedly higher CR rates and overall survival than currently used sequential regimens. Taken together, CyDRi proved to be an attractive option for the immunosuppression of elderly patients with AHA.

Recombinant von Willebrand factor prophylaxis in patients with severe von Willebrand disease: phase 3 study results.

International guidelines conditionally recommend long-term prophylaxis in patients with von Willebrand disease (VWD) and severe and frequent bleeding. As recombinant von Willebrand factor (rVWF; vonicog alfa) may reduce the frequency of treated spontaneous bleeding events (BEs), we investigated the efficacy and safety of rVWF prophylaxis in adults with severe VWD. Patients with BEs requiring VWF therapy in the past year (on-demand VWF therapy [prior on-demand group] or plasma-derived VWF prophylaxis [pdVWF; switch group]) were enrolled in a prospective, open-label, nonrandomized, phase 3 study. The planned duration of rVWF prophylaxis was 12 months; starting rVWF dose was 50 ± 10 VWF: ristocetin cofactor (VWF:RCo) IU/kg twice weekly (prior on-demand group) or based on prior pdVWF weekly dose/dosing frequency (switch group). The primary endpoint was annualized bleeding rate (ABR) of treated spontaneous BEs (sABR) during rVWF prophylaxis. Over the 12-month study period, treated sABR decreased by 91.5% on-study vs historical sABR in 13 patients in the prior on-demand group, and by 45.0% in 10 patients in the switch group (model-based analysis ratio, 0.085; 95% confidence interval [CI], 0.021-0.346 and 0.550; 95% CI, 0.086-3.523, respectively). No treated spontaneous BEs were recorded in 84.6% (11/13) and 70.0% (7/10) of patients, respectively. The safety profile of rVWF was consistent with the previously established profile, with no new adverse drug reactions identified. Findings suggest that rVWF prophylaxis can reduce treated spontaneous BEs in patients previously receiving on-demand VWF therapy and maintains at least the same level of hemostatic control in patients who switch from prophylaxis with pdVWF to rVWF, with a favorable safety profile. This trial was registered at www.clinicaltrials.gov (#NCT02973087) and www.clinicaltrialsregister.eu (#EudraCT 2016-001478-14).

Immune complications and their management in inherited and acquired bleeding disorders.

Disorders of coagulation, resulting in serious risks for bleeding, may be caused by autoantibody formation or by mutations in genes encoding coagulation factors. In the latter case, antidrug antibodies (ADAs) may form against the clotting factor protein drugs used in replacement therapy, as is well documented in the treatment of the X-linked disease hemophilia. Such neutralizing antibodies against factors VIII or IX substantially complicate treatment. Autoantibody formation against factor VIII leads to acquired hemophilia. Although rare, antibody formation may occur in the treatment of other clotting factor deficiencies (eg, against von Willebrand factor [VWF]). The main strategies that have emerged to address these immune responses include (1) clinical immune tolerance induction (ITI) protocols; (2) immune suppression therapies (ISTs); and (3) the development of drugs that can improve hemostasis while bypassing the antibodies against coagulation factors altogether (some of these nonfactor therapies/NFTs are antibody-based, but they are distinct from traditional immunotherapy as they do not target the immune system). Choice of immune or alternative therapy and criteria for selection of a specific regimen for inherited and autoimmune bleeding disorders are explained. ITI serves as an important proof of principle that antigen-specific immune tolerance can be achieved in humans through repeated antigen administration, even in the absence of immune suppression. Finally, novel immunotherapy approaches that are still in the preclinical phase, such as cellular (for instance, regulatory T cell [Treg]) immunotherapies, gene therapy, and oral antigen administration, are discussed.

Hemostatic and thrombotic disorders in the pediatric patient.

This review focuses on significant advances in the field of pediatric hemostasis and thrombosis, with a focus on published studies within the past decade. The evaluation and management of patients with excessive bleeding remain cornerstones of consultative hematology. We will describe the development of validated bleeding assessment tools relevant to pediatric practice, laboratory advances in the evaluation of von Willebrand disease, and a shift in clinical practice regarding the interpretation of normal coagulation studies in patients with significant bleeding phenotypes. There have also been critical advances in the management of hemostatic disorders. This review highlights new treatment paradigms in hemophilia and the rise of multidisciplinary medical homes for women living with bleeding disorders. Given the continued increase in the incidence of thrombosis, particularly in the hospital setting, a full call to arms against pediatric venous thromboembolism is now essential. We will describe recently completed clinical trials of direct oral anticoagulants in children and adolescents and ongoing work to elucidate the appropriate duration of therapy for children with provoked thrombosis. Recent work regarding the prevention of pediatric venous thromboembolism is highlighted, including studies of thromboprophylaxis and the development of risk prediction models for hospital-acquired thrombosis. Finally, we review advances in our understanding of thrombotic sequelae and the need for continued refinement of our evaluation tools. Despite the significant advances in pediatric hemostasis and thrombosis over the past decade, many unanswered questions remain for the next generation of investigators.

Rivaroxaban vs placebo for extended antithrombotic prophylaxis after laparoscopic surgery for colorectal cancer.

The clinical benefit of extended prophylaxis for venous thromboembolism (VTE) after laparoscopic surgery for cancer is unclear. The efficacy and safety of direct oral anticoagulants for this indication are unexplored. PROphylaxis of venous thromboembolism after LAParoscopic Surgery for colorectal cancer Study II (PROLAPS II) was a randomized, double-blind, placebo-controlled, investigator-initiated, superiority study aimed at assessing the efficacy and safety of extended prophylaxis with rivaroxaban after laparoscopic surgery for colorectal cancer. Consecutive patients who had laparoscopic surgery for colorectal cancer were randomized to receive rivaroxaban (10 mg once daily) or a placebo to be started at 7 ± 2 days after surgery and given for the subsequent 3 weeks. All patients received antithrombotic prophylaxis with low-molecular-weight heparin from surgery to randomization. The primary study outcome was the composite of symptomatic objectively confirmed VTE, asymptomatic ultrasonography-detected deep vein thrombosis (DVT), or VTE-related death at 28 ± 2 days after surgery. The primary safety outcome was major bleeding. Patient recruitment was prematurely closed due to study drug expiry after the inclusion of 582 of the 646 planned patients. A primary study outcome event occurred in 11 of 282 patients in the placebo group compared with 3 of 287 in the rivaroxaban group (3.9 vs 1.0%; odds ratio, 0.26; 95% confidence interval [CI], 0.07-0.94; log-rank P = .032). Major bleeding occurred in none of the patients in the placebo group and 2 patients in the rivaroxaban group (incidence rate 0.7%; 95% CI, 0-1.0). Oral rivaroxaban was more effective than placebo for extended prevention of VTE after laparoscopic surgery for colorectal cancer without an increase in major bleeding. This trial was registered at www.clinicaltrials.gov as #NCT03055026.

Long-term follow-up of liver-directed, adeno-associated vector-mediated gene therapy in the canine model of hemophilia A.

Questions remain concerning the long-term efficacy, safety, and site(s) of transgene expression following adeno-associated vector (AAV) therapy. We report a long-term follow-up of 8 (male = 4, hemizygous, and female = 4, homozygous) dogs with severe hemophilia A treated with a single portal vein infusion of a B-domain-deleted (BDD)-canine FVIII (cFVIII) AAV vector (median dose = 1.25 × 1013 vg/kg, AAV2 = 4, AAV6 = 3, and AAV8 = 1). After a median follow-up of 10.8 years (8.2-12.0 years), persistent FVIII:C (median one-stage = 12.7%, chromogenic = 7.2%) was seen in all responding dogs (n = 6), with improvement in annualized bleed rates (pre = 3.9 vs post = 0.3 event per year; P = .003). Anti-AAV capsid neutralizing antibodies (nAbs) toward the dosed capsid were detected throughout the study, with limited cross-reactivity to other capsids. nAb titers for all capsid serotypes declined with time, although they remained at levels precluding redosing with the same capsid. AAV-BDD-cFVIII DNA was detected in the liver of all dogs (median = 0.15 vg per diploid genome), with lower levels in the spleen in 4 dogs (median = 0.005 vg per diploid genome). Consistent with the liver-specific promoter, BDD-cFVIII mRNA was only detected in the liver. Postmortem examination demonstrated no evidence of chronic liver disease or liver malignancy. Persistent FVIII expression and an improved bleeding phenotype was seen for more than a decade after vector delivery. This is the longest follow-up reported in a preclinical model supporting long-term efficacy and safety of AAV-mediated gene therapy.

Ticagrelor vs placebo for the reduction of vaso-occlusive crises in pediatric sickle cell disease: the HESTIA3 study.

The phase 3 HESTIA3 study assessed the efficacy and safety of the reversible P2Y12 inhibitor ticagrelor vs placebo in preventing vaso-occlusive crises in pediatric patients with sickle cell disease (SCD). Patients aged 2 to 17 years were randomly assigned 1:1 to receive weight-based doses of ticagrelor or matching placebo. The primary end point was the rate of vaso-occlusive crises, a composite of painful crises and/or acute chest syndrome (ACS). Key secondary end points included number and duration of painful crises, number of ACS events, and number of vaso-occlusive crises requiring hospitalization or emergency department visits. Exploratory end points included the effect of ticagrelor on platelet activation. In total, 193 patients (ticagrelor, n = 101; placebo, n = 92) underwent randomization at 53 sites across 16 countries. The study was terminated 4 months before planned completion for lack of efficacy. Median ticagrelor exposure duration was 296.5 days. The primary end point was not met: estimated yearly incidence of vaso-occlusive crises was 2.74 in the ticagrelor group and 2.60 in the placebo group (rate ratio, 1.06; 95% confidence interval, 0.75-1.50; P = .7597). There was no evidence of efficacy for ticagrelor vs placebo across secondary end points. Median platelet inhibition with ticagrelor at 6 months was 34.9% predose and 55.7% at 2 hours' postdose. Nine patients (9%) in the ticagrelor group and eight patients (9%) in the placebo group had at least one bleeding event. In conclusion, no reduction of vaso-occlusive crises was seen with ticagrelor vs placebo in these pediatric patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT03615924.