Routine use of fondaparinux in acute coronary syndromes: a 2-year multicenter experience

Caltrop-like Small-Molecule Antidotes That Neutralize Unfractionated Heparin and Low-Molecular-Weight Heparin In Vivo

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs) are widely applied for surgical procedures and extracorporeal therapies, which, however, suffer bleeding risk. Protamine, the only clinically approved antidote, can completely neutralize UFH, but only partially neutralizes LMWHs, and also has a number of safety drawbacks. Here, we show that caltrop-like multicationic small molecules can completely neutralize both UFH and LMWHs. In vitro and ex vivo assays with plasma and whole blood and in vivo assays with mice and rats support that the lead compound is not only superior to protamine by displaying higher neutralization activity and broader therapeutic windows but also biocompatible. The effective neutralization dose and the maximum tolerated dose of the lead compound are determined to be 0.4 and 25 mg/kg in mice, respectively, suggesting good promise for further preclinical studies.

Porous Polymers as Universal Reversal Agents for Heparin Anticoagulants through an Inclusion-Sequestration Mechanism

Heparins are widely used anticoagulants for surgical procedures and extracorporeal therapies. However, all of them have bleeding risks. Protamine sulfate, the only clinically approved antidote for unfractionated heparin (UFH), has adverse effects. Moreover, protamine can only partially neutralize low-molecular-weight heparins (LMWHs) and is not effective for fondaparinux. Here, an inclusion-sequestration strategy for efficient neutralization of heparin anticoagulants by cationic porous supramolecular organic frameworks (SOFs) and porous organic polymers (POPs) is reported. Isothermal titration calorimetric and fluorescence experiments show strong binding affinities of these porous polymers toward heparins, whereas dynamic light scattering and zeta potential analysis confirm that the heparin sequences are adsorbed into the interior of the porous hosts. Activated partial thromboplastin time, anti-FXa, and thromboelastography assays indicate that their neutralization efficacies are higher than or as high as that of protamine for UFH and generally superior to protamine for LMWHs and fondaparinux, which is further confirmed by tail-transection model in mice and ex vivo aPTT or anti-FXa analysis in rats. Acute toxicity evaluations reveal that one of the SOFs displays outstanding biocompatibility. This work suggests that porous polymers can supply safe and rapid reversal of clinically used heparins, as protamine surrogates, providing an improved approach for their neutralization.

Fondaparinux versus enoxaparin in the contemporary management of non-ST-elevation acute coronary syndromes. Insights from a multicenter registry

BACKGROUND

Fondaparinux is thought to have the most favorable risk-benefit profile among all anticoagulants in non-ST-elevation acute coronary syndrome (NSTE-ACS). However, conflicting findings exist whether this holds true in current clinical practice. We aimed to assess the net clinical benefit of fondaparinux versus enoxaparin in the contemporary management of NSTE-ACS.

METHODS

Analysis of prospective multicenter registry data of NSTE-ACS patients who received fondaparinux or enoxaparin from February 2015, through December 2017. Survival models within a competing risks framework including site-specific random effects, were used to assess the composite of clinically relevant bleedings and major adverse cardiovascular events at 30 days.

RESULTS

Of 2094 patients, 1724 (82%) received enoxaparin and 370 (18%) fondaparinux. Both groups were comparable except for a lower prevalence of diabetes and renal impairment, and greater use of transradial approach in the fondaparinux group. Multivariate analysis revealed a net clinical benefit in favour of fondaparinux versus enoxaparin (Subhazard Ratio [SHR] 0.59; 95%CI 0.37-0.92), mainly driven by a reduction in bleeding (SHR 0.57; 95%CI 0.37-0.89). Exploratory analysis suggested greater reductions in bleeding with fondaparinux among patients undergoing transradial approach, revealing a significant interaction between treatment and vascular access on the multiplicative scale (P_interaction = 0.0056), but not on an additive scale (P = 0.457). Propensity-score-matching analysis yielded similar results.

CONCLUSIONS

In contemporary management of NSTE-ACS, fondaparinux seems to provide a favorable net clinical benefit compared with enoxaparin, primarily driven by a bleeding reduction. Effect modification on the safety profile of fondaparinux by the vascular access approach warrants further investigation.

Lost in (Clinical) Translation: Recent Advances in Heparin Neutralization and Monitoring

The heparin family, which includes unfractionated heparin, low-molecular heparin, and fondaparinux, is a class of drugs clinically used as intravenous blood thinners. To date, issues related to both the reversal of anticoagulation and the blood level determination of the anticoagulant at the point-of-care remain: while the only U.S. Food and Drug Administration (FDA) approved antidote for heparin displays serious efficacy and safety drawbacks, the current assays for heparin monitoring are indirect measurements subject to their own limitations and variations. Herein, we provide an update on the numerous recent chemical approaches to tackle these issues, from which it is clear that some new antidotes and sensors for heparin certainly have the potential to exceed current clinical standards. This review aims to review a field that requires close collaborations between physicians, biologists, and chemists in order to foster advances toward clinical translation.

Dendrigraft of Poly-l-lysine as a Promising Candidate To Reverse Heparin-based Anticoagulants in Clinical Settings

By using a combination of experimental and computational experiments, we demonstrated that a second-generation dendrigraft of poly-l-lysine neutralizes the anticoagulant activity of unfractionated heparin, low-molecular-weight heparin, and fondaparinux more efficiently than protamine does in human plasma, making this synthetic polymer a promising surrogate of this problematic protein in clinical settings.

Choosing between Enoxaparin and Fondaparinux for the management of patients with acute coronary syndrome: A systematic review and meta-analysis

BACKGROUND

Enoxaparin and Fondaparinux are potential anticoagulants which are used peri-operatively in the management of patients with Acute Coronary Syndrome (ACS). We aimed to compare the adverse clinical outcomes which are associated with the use of these anticoagulants in patients who were treated for ACS.

METHODS

Online databases (PubMed/Medline, EMBASE, Cochrane library) were searched for studies which compared differences in clinical outcomes observed with the use of enoxaparin and fondaparinux in patients who were treated peri-operatively for ACS. Statistical analysis was carried out by Revman 5.3 software with odds ratio (OR) and 95% confidence intervals (CI) as the analytical parameters.

RESULTS

Seven studies with a total number of 9618 patients (mainly composed of non-ST elevated myocardial infarction/NSTEMI) were included. This analysis showed mortality to be similarly observed between enoxaparin and fondaparinux with OR: 1.05, 95% CI: 0.67-1.63; P = 0.84. Myocardial infarction (MI) and stroke were also not significantly different throughout different follow up periods. However, minor, major and total bleeding were significantly lower with fondaparinux (OR: 0.40, 95% CI: 0.27-0.58; P = 0.00001), (OR: 0.46, 95% CI: 0.32-0.66; P = 0.0001) and (OR: 0.47, 95% CI: 0.37-0.60; P = 0.00001) respectively during the 10-day follow up period. Even during a follow up period of 30 days or a midterm follow up, major and minor bleeding still significantly favored fondaparinux in comparison to enoxaparin.

CONCLUSION

In patients who were treated for ACS, fondaparinux might be a better choice when compared to enoxaparin in terms of short to midterm bleeding events. This result was mainly applicable to patients with NSTEMI. However, due to a limited number of patients analyzed, further larger randomized trials should be able to confirm this hypothesis.

Fondaparinux versus Enoxaparin - Which is the Best Anticoagulant for Acute Coronary Syndrome? - Brazilian Registry Data

Background:

Recent studies have shown fondaparinux's superiority over enoxaparin in patients with non-ST elevation acute coronary syndrome (ACS), especially in relation to bleeding reduction. The description of this finding in a Brazilian registry has not yet been documented.

Objective:

To compare fondaparinux versus enoxaparin in in-hospital prognosis of non-ST elevation ACS.

Methods:

Multicenter retrospective observational study. A total of 2,282 patients were included (335 in the fondaparinux group, and 1,947 in the enoxaparin group) between May 2010 and May 2015. Demographic, medication intake and chosen coronary treatment data were obtained. Primary outcome was mortality from all causes. Secondary outcome was combined events (cardiogenic shock, reinfarction, death, stroke and bleeding). Comparison between the groups were done through Chi-Square test and T test. Multivariate analysis was done through logistic regression, with significance values defined as p < 0.05.

Results:

With regards to treatment, we observed the performance of a percutaneous coronary intervention in 40.2% in the fondaparinux group, and in 35.1% in the enoxaparin group (p = 0.13). In the multivariate analysis, we observed significant differences between fondaparinux and enoxaparin groups in relation to combined events (13.8% vs. 22%. OR = 2.93, p = 0.007) and bleeding (2.3% vs. 5.2%, OR = 4.55, p = 0.037), respectively.

Conclusion:

Similarly to recently published data in international literature, fondaparinux proved superior to enoxaparin for the Brazilian population, with significant reduction of combined events and bleeding.

Affinity-based design of a synthetic universal reversal agent for heparin anticoagulants

Heparin-based anticoagulant drugs have been widely used for the prevention of blood clotting during surgical procedures and for the treatment of thromboembolic events. However, bleeding risks associated with these anticoagulants demand continuous monitoring and neutralization with suitable antidotes. Protamine, the only clinically approved antidote to heparin, has shown adverse effects and ineffectiveness against low-molecular weight heparins and fondaparinux, a heparin-related medication. Alternative approaches based on cationic molecules and recombinant proteins have several drawbacks including limited efficacy, toxicity, immunogenicity, and high cost. Thus, there is an unmet clinical need for safer, rapid, predictable, and cost-effective anticoagulant-reversal agents for all clinically used heparins. We report a design strategy for a fully synthetic dendritic polymer-based universal heparin reversal agent (UHRA) that makes use of multivalent presentation of branched cationic heparin binding groups (HBGs). Optimization of the UHRA design was aided by isothermal titration calorimetry studies, biocompatibility evaluation, and heparin neutralization analysis. By controlling the scaffold's molecular weight, the nature of the protective shell, and the presentation of HBGs on the polymer scaffold, we arrived at lead UHRA molecules that completely neutralized the activity of all clinically used heparins. The optimized UHRA molecules demonstrated superior efficacy and safety profiles and mitigated heparin-induced bleeding in animal models. This new polymer therapeutic may benefit patients undergoing high-risk surgical procedures and has potential for the treatment of anticoagulant-related bleeding problems.

Impact of fondaparinux versus enoxaparin on in-hospital bleeding and 1-year death in non-ST-segment elevation myocardial infarction. FAST-MI (French Registry of Acute ST-elevation and non-ST-elevation Myocardial Infarction) 2010

AIMS

Fondaparinux is an alternative to low molecular weight heparin (LMWH) for non-ST-elevation myocardial infarction (NSTEMI) with levels of recommendation that differ according to guidelines. The aim of this study was to assess outcomes in real world practice in NSTEMI patients participating in the French Registry of ST-elevation and non-ST-elevation Myocardial Infarction (FAST-MI) 2010 according to the use of fondaparinux, in comparison with patients receiving enoxaparin.

METHODS AND RESULTS

FAST-MI 2010 is a nationwide French registry that included 4,169 patients with acute myocardial infarction at the end of 2010 in 213 centres (76% of active centres in France); 1,734 had NSTEMI, with 240 receiving fondaparinux and 1,027 enoxaparin. Patients receiving enoxaparin vs. fondaparinux had essentially characteristics with a similar GRACE (Global Registry of Acute Coronary Events) score. Invasive strategy was used in 69% in both groups. In-hospital bleeding was similar with both anticoagulant strategies and 1-year survival was 94.6% and 91.7%, respectively. Using fully adjusted Cox multivariate analysis, the use of fondaparinux was not associated with a reduced risk of death (hazard ratio: 1.35; 95% confidence interval: 0.70-2.51). After propensity score matching (207 patients per group), 1-year survival was similar with both strategies. There was, however, an interaction between fondaparinux and unfractionated heparin, with higher survival in fondaparinux-treated patients who received UFH, compared with those who did not.

CONCLUSIONS

In this French cohort of NSTEMI patients, predominantly managed invasively, there was no evidence that fondaparinux was superior to enoxaparin as regards bleeding events or 1-year mortality (FAST-MI 2010; NCT01237418).

Emerging therapies for acute coronary syndromes

In the majority of cases acute coronary syndromes (ACS) are caused by activation and aggregation of platelets and subsequent thrombus formation leading to a decrease in coronary artery blood flow. Recent focus on the treatment of ACS has centered on reducing the response of platelets to vascular injury as well as inhibiting fibrin deposition. Novel therapies include more effective P2Y12 receptor blockers thereby reducing inter-individual variability, targeting the platelet thrombin receptor (protease activated receptor 1) as well as directly inhibiting factor Xa or thrombin activity. In this review we discuss the clinical data evaluating the effectiveness of these various new ACS treatment options.

Fondaparinux and acute coronary syndromes: update on the OASIS 5-6 studies

Anticoagulant therapy is a major component in the management of acute coronary syndromes (ACS). Four anticoagulant agents are currently commercially available for ACS, namely unfractionated heparin (UFH), enoxaparin, bivalirudin and fondaparinux. We describe the advantages of fondaparinux and the reasons that have hampered its uptake into routine management of ACS. Fondaparinux was shown to be efficacious in the prevention of deep vein thrombosis vs low-molecular-weight heparins, while in the setting of venous thrombo-embolic disease, it was shown to be noninferior to enoxaparin and UFH. Two pivotal studies have demonstrated the efficacy of fondaparinux as an anticoagulant in the setting of ACS, namely OASIS-5 in non-ST elevation ACS, and OASIS-6 in ST elevation myocardial infarction (MI). In OASIS-5, fondaparinux was shown to be noninferior to enoxaparin in terms of death, MI or refractory ischemia at 9 days. Furthermore, a 50% reduction in bleeding complications was obtained with fondaparinux vs enoxaparin, leading to a risk reduction for death. In OASIS-6, fondaparinux was shown to be superior to the comparator (UFH or placebo). European and North American guidelines give fondaparinux a Grade 1A and 1B recommendation respectively, but uptake of fondaparinux in routine practice has been slow. We explore reasons for this, such as prevailing doubts about the efficacy of fondaparinux in the setting of angioplasty, the problem of catheter thrombosis, and the lack of antidote in case of bleeding complications. With the exception of primary angioplasty, fondaparinux is as effective as enoxaparin or UFH, but is also associated with a considerable reduction in bleeding complications, and thus, an undeniable net clinical benefit.