Update of the recommendations on biosimilar low-molecular-weight heparins from the Scientific Subcommittee on Control of Anticoagulation of the International Society on Thrombosis and Haemostasis

Fucoidans of Brown Algae: Comparison of Sulfated Polysaccharides from Fucus vesiculosus and Ascophyllum nodosum

Preparations of sulfated polysaccharides obtained from brown algae are known as fucoidans. These biopolymers have attracted considerable attention due to many biological activities which may find practical applications. Two Atlantic representatives of Phaeophyceae, namely, Fucus vesiculosus and Ascophyllum nodosum, belonging to the same order Fucales, are popular sources of commercial fucoidans, which often regarded as very similar in chemical composition and biological actions. Nevertheless, these two fucoidan preparations are polysaccharide mixtures which differ considerably in amount and chemical nature of components, and hence, this circumstance should be taken into account in the investigation of their biological properties and structure-activity relationships. In spite of these differences, fractions with carefully characterized structures prepared from both fucoidans may have valuable applications in drug development.

Anticoagulant activity and pleiotropic effects of heparin

The recognized therapeutic effect of heparins is an anticoagulant activity (anti-Xa and anti-IIa) acting in an indirect manner (cofactor of antithrombin) but which is carried by only 20% at best of the glycan chains composing any commercial preparation of heparin, whether unfractionated or low molecular weight. However, the effects of glycan chains that participate in the therapeutic but also potentially adverse effects of heparin preparations must also be considered. These specific effects of glycans are potentially different for each commercial preparation of heparins and, in particular, low molecular weight heparins (LMWH) compared with unfractionated heparin (UFH) and LMWH between them. The glycanic nature of heparin is responsible for its very particular pharmacology: exchange with the glycocalyx of cells in particular endothelial. Exchanges which depend on the length and structure of the glycan chains therefore different between UFH and LMWH between the different heparin preparations between them but also according to the state of glycocalyx differently altered according to the underlying diseases and their degree of evolution. If the anticoagulant effects of heparins can potentially be replaced with those of new oral anticoagulants, the glycan effects of heparins cannot be replaced by synthetic non-glycan molecules. This replacement will undoubtedly limit certain risks such as heparin-induced thrombocytopenia (HIT) but other beneficial effects participating to the overall efficacy of heparin (whose relative importance remains to be ascertained), will also disappear: effects on surfaces, anti-inflammatory effects, antineoplastic and anti-metastatic effects, ancillary anticoagulant effects (not dependent on antithrombin), effect on endothelial dysfunction. This review will be focused on all of these related/pleiotropic effects of heparins that are in fact the effects of the glycan nature of heparin. Among the antithrombotic effects not dependent on antithrombin one has been more recently highlighted: the passivation/neutralization of the positively charged fibrils of Netosis, by the negatively charged glycan chains of heparin. This also has clinical implications: in the era of generics and biosimilars where biosimilar heparins begin to appear, it is important to know that accordingly to FDA and EMEA rules: their biosimilarity is judged only on the "classical" anticoagulation effect cofactor of antithrombin (anti-IIa/anti-Xa) but that all glycan effects that are potentially beneficial or potentially deleterious are not taken into consideration in their assessment.

Biosimilars of low molecular weight heparins: Relevant background information for your drug formulary

Biosimilars of low molecular weight heparins (LMWHs) are more alike the originator than different branded LMWHs. The latter differ largely in molecular weight, anti-FXa/anti-FIIa ratio and antithrombin binding. The Food and Drug Administration and European Medicines Agency guidelines are sufficient for the clinical use of high quality LMWHs. However, the Food and Drug Administration guideline lacks the results of a phase I clinical trial in the approval process. Most information about biosimilars is available for enoxaparin given that many biosimilars of enoxaparin have received market access. The guidelines of many International Thrombosis Societies for LMWH biosimilars are too stringent, not updated and impractical for formulary uptake discussions. This review gives background information on critical factors for the formulary uptake process of LMWHs with special attention for the use of the System of Objectified Judgment Analysis/Infomatrix model.

Structural and functional analyses of biosimilar enoxaparins available in Brazil

Biosimilar enoxaparins have been available for clinical use in Brazil since 2009. Although their use has reduced costs of treatment expenses, their implementation still raises some concerns about efficiency, safety, regularity and reproducibility of batches. We undertook structural and functional analyses on over 90 batches of pharmaceutical- active ingredient, and 330 ones of the final products of biosimilar enoxaparins available in the Brazilian market between 2009 and 2014. Besides a nationwide-scale analysis, we have also employed methods that go beyond those recommended by the standard pharmacopeias. We have used high-resolution 2D NMR, detailed assessment of the anticoagulant and antithrombotic properties, check of side effects in experimental animals after continuous administration, and analyses of individual composing oligosaccharides. The 1D 1H NMR spectra of all batches of biosimilar enoxaparins are fairly coincident, and the resultant average spectrum is quite identical to that from the original drug. This structural equality was also assured by highly resolved 2D NMR spectra. The anticoagulant activity, determined by diverse assays and the in vivoantithrombotic and bleeding effects of the biosimilar version were confirmed as equal as of the parental enoxaparins. Structure and function of the composing oligosaccharides were identical in both enoxaparin types. No side effect was observed after continuous subcutaneous administration to rats for 30 days at the dose of 2 mg kg-1 body weight. Biosimilar enoxaparins available in Brazil fulfilled the requirement of the five items defined by FDA-USA for approval of this type of drug.

The introduction of biosimilars of low molecular weight heparins in Europe: a critical review and reappraisal endorsed by the Italian Society for Haemostasis and Thrombosis (SISET) and the Italian Society for Angiology and Vascular Medicine (SIAPAV)

Recently, the European Medicines Agency (EMA) authorized the introduction and marketing of Thorinane® and Inhixa®, biosimilars of the Low Molecular Weight Heparin (LMWH) enoxaparin. The authorization path is considerably different from the guidelines published by the EMA in 2009, as well as from the recommendations from the International Society on Thrombosis and Haemostasis published in 2013. Indeed, both of them recommended that LMWHs biosimilars therapeutic equivalence should be demonstrated in at least one adequately designed clinical trial. Shortly after enoxaparin biosimilars approval, EMA published a revised version of its guideline, no longer requiring the execution of a clinical study in patients at risk of venous thromboembolism.

Also the assessment of safety shows some relevant flaws, as it relies only on a 20 healthy volunteers study, clearly underpowered to draw any conclusions about the safety profile of the drug.

In our opinion, the approach taken by EMA for approval of enoxaparin biosimilars raises serious concerns about their actual, clinical “similarity”.

On these grounds, with the endorsement of the Italian Society for Haemostasis and Thrombosis (SISET) and the Italian Society for Angiology and Vascular Medicine (SIAPAV), we elaborated the present document aimed at reviewing and reappraising some critical points regarding the introduction of biosimilars of LMWH in Europe.

Moreover, we would strongly advise the Italian National Health Authorities not to entrust safety assessment to the post-marketing surveillance only, but to promote well designed and powered studies aimed at establish the actual efficacy and safety of LMWH biosimilars.

Update on Brazilian biosimilar enoxaparins

INTRODUCTION

Brazil is among the first countries approving the commercialization and clinical use of biosimilar enoxaparins. Our research group has performed quality control assessments of these drugs over the last decade. Areas covered: We have not found noticeable differences between Brazilian biosimilar enoxaparins and the original product regarding their physicochemical properties, disaccharide composition, anticoagulant activity, bioavailability and safety. Expert commentary: In spite of clinical and pharmacological advantages of enoxaparin, subcutaneous formulations of unfractionated heparin are employed by the Brazilian public health system for prevention and treatment of thromboembolism. The underuse of both original and biosimilar enoxaparins in Brazil directly correlates with their high cost.

Biosimilars of low-molecular-weight heparin products: fostering competition or reducing 'biodiversity'?

The term 'biosimilars' is used to qualify products developed to be similar to an original biological drug. Biosimilars are much more complicated to develop than a generic version of small-molecule drugs and this is especially true for low-molecular-weight heparins (LMWHs). Evidence on the antithrombotic management of acute coronary syndromes (ACS) showed that the introduction into the market of biosimilars approved on the basis of simple biological criteria, without robust data from comparative clinical trials, may be hazardous. Moreover, the mixtures of LMWH polysaccharide chains, some immunoallergic properties and potential contamination during the extraction process raise safety concerns. As was the case for the biosimilar erythropoietin, there is the risk that only copies of the most commercially successful LMWHs will be marketed, thus jeopardizing the 'biodiversity' now ensured by the presence of several LMWHs, each with unique features that support the use of an individual LMWH as first-choice therapy in certain categories of patients.

Analytical and statistical comparability of generic enoxaparins from the US market with the originator product

Low-molecular-weight heparins (LMWHs) are complex anticoagulant drugs, made from heparin porcine mucosa starting material. Enoxaparin sodium manufactured by Sanofi is one of the most widely prescribed LMWHs and has been used since 1993 in the USA. In 2010, US Food and Drug Administration approval for supplying generic enoxaparin was granted to Sandoz and subsequently to Amphastar. Little is known, however, of the differences in composition of these preparations. In this study, samples from several batches of generic enoxaparins were purchased on the US market and analyzed with state of the art methodologies, including disaccharide building blocks quantification, nuclear magnetic resonance (NMR), and a combination of orthogonal separation techniques. Direct high-performance liquid chromatography analysis of the different enoxaparin batches revealed distinct process fingerprints associated with each manufacturer. Disaccharide building block analysis showed differences in the degree of sulfation, the presence of glycoserine derivatives, as well as in proportions of disaccharides. Results were compared by statistical approaches using multivariate analysis with a partial least squares discriminant analysis methodology. The variations were statistically significant and allowed a clear distinction to be made between the enoxaparin batches according to their manufacturer. These results were further confirmed by orthogonal analytical techniques, including NMR, which revealed compositional differences of oligosaccharides both in low- and high-affinity antithrombin fractions of enoxaparin.

Antithrombin-binding oligosaccharides: structural diversities in a unique function?

Heparin-antithrombin interaction is one of the most documented examples of heparin/protein complexes. The specific heparin sequence responsible for the binding corresponds to a pentasaccharide sequence with an internal 3-O-sulfated glucosamine residue. Moreover, the position of the pentasaccharide along the chain as well as the structure of the neighbor units affects the affinity to antithrombin. The development of separation and purification techniques, in conjunction with physico-chemical approaches (mostly NMR), allowed to characterize several structural variants of antithrombin-binding oligosaccharides, both in the free state and in complex with antithrombin. The article provides an overview of the studies that lead to the elucidation of the mechanism of interaction as well as acquiring new knowledge in heparin biosynthesis.

Re-visiting the structure of heparin

The sulfated polysaccharide heparin has been used as a life-saving anticoagulant in clinics well before its detailed structure was known. This mini-review is a survey of the evolution in the discovery of the primary and secondary structure of heparin. Highlights in this history include elucidation and synthesis of the specific sequence that binds to antithrombin, the development of low-molecular-weight heparins currently used as antithrombotic drugs, and the most promising start of chemo-enzymatic synthesis. Special emphasis is given to peculiar conformational properties contributing to interaction with proteins that modulate different biological properties.