Thrombosis and haemostasis最新文献

The binding promiscuity of proteins defines their ability to indiscriminately bind multiple unrelated molecules. Binding promiscuity is implicated, at least in part, in the off-target reactivity, nonspecific biodistribution, immunogenicity, and/or short half-life of potentially efficacious protein drugs, thus affecting their clinical use. In this review, we discuss the current evidence for the binding promiscuity of factor VIII (FVIII), a protein used for the treatment of hemophilia A, which displays poor pharmacokinetics, and elevated immunogenicity. We summarize the different canonical and noncanonical interactions that FVIII may establish in the circulation and that could be responsible for its therapeutic liabilities. We also provide information suggesting that the FVIII light chain, and especially its C1 and C2 domains, could play an important role in the binding promiscuity. We believe that the knowledge accumulated over years of FVIII usage could be exploited for the development of strategies to predict protein binding promiscuity and therefore anticipate drug efficacy and toxicity. This would open a mutational space to reduce the binding promiscuity of emerging protein drugs while conserving their therapeutic potency.

Background:  In most patients with cancer-associated venous thromboembolism (CT), essentially those not at high risk of bleeding, guidelines recommend treatment with direct oral anticoagulants as an alternative to low-molecular-weight heparins (LMWHs). Population-based studies comparing these therapies are scarce.

Objectives:  To compare the risk of venous thromboembolism (VTE) recurrences, significant bleeding, and all-cause mortality in patients with CT receiving rivaroxaban or LMWHs.

Patients/methods:  Using UK Clinical Practice Research Datalink data from 2013 to 2020, we generated a cohort of patients with first CT treated initially with either rivaroxaban or LMWH. Patients were observed 12 months for VTE recurrences, significant bleeds (major bleeds or clinically relevant nonmajor bleeding requiring hospitalization), and all-cause mortality. Overlap weighted sub-distribution hazard ratios (SHRs) compared rivaroxaban with LMWH in an intention-to-treat analysis.

Results:  The cohort consisted of 2,259 patients with first CT, 314 receiving rivaroxaban, and 1,945 LMWH, mean age 72.4 and 66.9 years, respectively. In the 12-month observational period, 184 person-years following rivaroxaban and 1,057 following LMWH, 10 and 66 incident recurrent VTE events, 20 and 102 significant bleeds, and 10 and 133 deaths were observed in rivaroxaban and LMWH users, respectively. The weighted SHR at 12 months for VTE recurrences in rivaroxaban compared with LMWH were 0.80 (0.37-1.73); for significant bleeds 1.01 (0.57-1.81); and for all-cause mortality 0.49 (0.23-1.06).

Conclusion:  Patients with CT, not at high risk of bleeding, treated with either rivaroxaban or LMWH have comparable effectiveness and safety outcomes. This supports the recommendation that rivaroxaban is a reasonable alternative to LMWH for the treatment of CT.

Background:  Platelets prevent extravasation of capillary fluids into the pulmonary interstitial tissue by sealing gaps in inflamed endothelium. This reduces respiratory distress associated with pneumonia. Streptococcus pneumoniae is the leading cause of severe community-acquired pneumonia. Pneumococci produce pneumolysin (PLY), which forms pores in membranes of eukaryotic cells including platelets. Additionally, pneumococci express neuraminidases, which cleave sialic acid residues from eukaryotic glycoproteins. In this study, we investigated the effect of desialylation on PLY binding and pore formation on platelets.

Materials and methods:  We incubated human platelets with purified neuraminidases and PLY, or nonencapsulated S. pneumoniae D39/TIGR4 and isogenic mutants deficient in PLY and/or NanA. We assessed platelet desialylation, PLY binding, and pore formation by flow cytometry. We also analyzed the inhibitory potential of therapeutic immunoglobulin G preparations (IVIG [intravenous immunoglobulin]).

Results:  Wild-type pneumococci cause desialylation of platelet glycoproteins by neuraminidases, which is reduced by 90 to 100% in NanA-deficient mutants. NanC, cleaving only α2,3-linked sialic acid, induced platelet desialylation. PLY binding to platelets then x2doubled (p = 0.0166) and pore formation tripled (p = 0.0373). A neuraminidase cleaving α2,3-, α2,6-, and α2,8-linked sialic acid like NanA was even more efficient. Addition of polyvalent IVIG (5 mg/mL) decreased platelet desialylation induced by NanC up to 90% (p = 0.263) and reduced pore formation >95% (p < 0.0001) when incubated with pneumococci.

Conclusion:  Neuraminidases are key virulence factors of pneumococci and desialylate platelet glycoproteins, thereby unmasking PLY-binding sites. This enhances binding of PLY and pore formation showing that pneumococcal neuraminidases and PLY act in concert to kill platelets. However, human polyvalent immunoglobulin G preparations are promising agents for therapeutic intervention during severe pneumococcal pneumonia.

Background:  Baseline thrombocytopenia is commonly observed in patients with acute coronary syndrome (ACS) requiring percutaneous coronary intervention (PCI).

Aim:  The purpose of this analysis was to investigate safety and effectiveness of PCI in ACS patients with baseline mild-to-moderate thrombocytopenia.

Methods:  The data were collected from the Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome project. A total of 50,009 ACS patients were recruited between July 2017 and December 2019. Among them, there were 6,413 patients with mild-to-moderate thrombocytopenia, defined as a platelet count of ≥50 × 10⁹/L and <150 × 10⁹/L on admission. The primary outcome was in-hospital net adverse clinical events (NACE), consisting of major adverse cardiac events (MACE) and major bleeding events. The associations between PCI and in-hospital outcomes were analyzed by inverse probability treatment weighting (IPTW) method.

Results:  PCI was performed in 4,023 of 6,413 patients (62.7%). The IPTW analysis showed that PCI was significantly associated with a reduced risk of in-hospital MACE (odd ratio [OR]: 0.45; 95% confidence interval [CI]: 0.31-0.67; p < 0.01) and NACE (OR: 0.59; 95% CI: 0.42-0.83; p < 0.01). PCI was also associated with an increased risk of any bleeding (OR: 1.56; 95% CI: 1.09-2.22; p = 0.01) and minor bleeding (OR: 1.52; 95% CI: 1.00-2.30; p = 0.05), but not major bleeding (OR: 1.51; 95% CI: 0.76-2.98; p = 0.24).

Conclusion:  Compared with medical therapy alone, PCI is associated with better in-hospital outcomes in ACS patients with mild-to-moderate thrombocytopenia. Further studies with long-term prognosis are needed.

Background:  Protein Z-dependent protease inhibitor (ZPI) is an anticoagulant serpin that targets factor Xa (FXa) in the presence of protein Z (PZ), and factor XIa (FXIa). In factor-VIII-deficient mice, PZ or ZPI gene knock-out mitigates the bleeding phenotype, and pharmacological inhibition of PZ enhances thrombin generation in plasma from patients with hemophilia.

Aims:  To develop a single-domain antibody (sdAb) directed against ZPI to inhibit its anticoagulant activity.

Methods:  We screened for anti-ZPI sdAbs in a llama-derived phage display immune library of sdAbs. The sdAbs that bound ZPI were produced and purified for characterization. The binding of sdAbs to ZPI or other serpins was evaluated using ELISAs, and ZPI inhibition was measured in an anti-FXa or anti-FXIa chromogenic assay. The sdAbs's procoagulant activity was assessed in a thrombin generation assay in normal plasma, factor VIII- and FXI-deficient plasma.

Results:  Of the four sdAbs found to bind to ZPI, one (referred to as ZPI-sdAb2) dose-dependently inhibited ZPI's anti-FXa and anti-FXIa activities with a mean half-maximal inhibitory concentration of 1.8 and 1.3 µM, respectively. ZPI-sdAb2 did not cross-react with other plasma serpins, such as antithrombin and α1-antitrypsin. ZPI-sdAb2 induced a significant increase in thrombin generation in plasma samples from healthy donors, patients with severe hemophilia A, and patients with FXI deficiency.

Conclusion:  ZPI-sdAb2 is the first specific, direct ZPI inhibitor found to exhibit procoagulant activity in plasma. This sdAb might have potential as a treatment for hemophilia or other bleeding disorders.

Background:  Venous thromboembolism (VTE) may complicate the clinical course of cancer patients and add to their psychological burden.

Objectives:  We aimed to investigate the association between VTE and risk of subsequent depression in patients with hematological cancer.

Patients and methods:  We conducted a population-based cohort study using Danish national health registries. Between 1995 and 2020, we identified 1,190 patients with hematological cancer and incident VTE diagnosed within 6 months before to 1 year after cancer diagnosis. A comparison cohort of patients with hematological cancer without VTE (n = 5,325) was matched by sex, year of birth, cancer type, and year of cancer diagnosis. Patients were followed until diagnosis of depression, emigration, death, study end (2021), or for a maximum of 3 years. Depression was defined as hospital discharge diagnosis of depression or ≥1 prescription for antidepressants. Absolute risks of depression were computed with cumulative incidence functions, treating death as competing event. Hazard ratios (HRs) with 95% confidence intervals (CIs) were computed using Cox proportional hazards regression models, adjusting for comorbidities.

Results:  Depression was observed in 158 hematological cancer patients with and 585 without VTE. The 3-year absolute risks of depression were 13.3% (95% CI: 11.5-15.3%) in the VTE cancer cohort and 11.1% (95% CI: 10.3-12.0%) in the comparison cancer cohort, corresponding to a risk difference of 2.2% (95% CI: -1.8-6.5%). VTE was associated with an increased relative risk of depression (adjusted HR: 1.56, 95% CI: 1.28-1.90).

Conclusion:  VTE was associated with an elevated risk of subsequent depression in patients with hematological cancer.

Background:  While direct oral anticoagulants (DOACs) may be viewed as simpler to manage then warfarin, they present their own unique management challenges resulting in frequent off-label dosing. It is unknown to what extent off-label dosing occurs when a patient is started on a DOAC versus later in their treatment.

Objectives:  We aimed to better characterize when off-label DOAC dosing is occurring and to evaluate the effectiveness of prescribing oversight using a registry-based intervention.

Methods:  We evaluated data from the Michigan Anticoagulation Quality Improvement Initiative (MAQI²) registry, a retrospective quality-improvement process using data abstractors, from 2018 to 2022 on the number of "alerts" that are generated in response to dosing deviating from the U.S. Food and Drug Administration instructions for atrial fibrillation (AF) and venous thromboembolism (VTE).

Results:  Among a sample of 789 to 1,022 annual AF patients and 381 to 484 annual VTE patients prescribed a DOAC in the MAQI² registry, off-label dosing was relatively common. Over the 5-year period (2018-2022), there were 569 alerts for AF patients and 162 alerts for VTE patients. Alerts occurred more frequently during follow-up than at the time of initial prescribing in AF patients (78.2 vs. 21.8%), but more commonly at initial prescribing in VTE patients (59.9 vs. 40.1%). After initial review by quality-improvement abstractors, 19.3% of AF alerts and 14.8% of VTE alerts resulted in contact to the prescriber. When the prescriber was contacted, it led to an intervention about 75% of the time for both populations. The most common intervention was a change in DOAC dosing.

Conclusion:  This study demonstrates the benefit of DOAC prescribing oversight using a registry-based intervention to monitor for off-label dosing for the entirety of the time period a patient is prescribed DOAC, particularly for patients with AF, as off-label prescribing occurs frequently during the follow-up period.