Biosimilars: what clinicians should know.

Biosimilar medicinal products (biosimilars) have become a reality in the European Union and will soon be available in the United States. Despite an established legal pathway for biosimilars in the European Union since 2005 and increasing and detailed regulatory guidance on data requirements for their development and licensing, many clinicians, particularly oncologists, are reluctant to consider biosimilars as a treatment option for their patients. Major concerns voiced about biosimilars relate to their pharmaceutical quality, safety (especially immunogenicity), efficacy (particularly in extrapolated indications), and interchangeability with the originator product. In this article, the members and experts of the Working Party on Similar Biologic Medicinal Products of the European Medicines Agency (EMA) address these issues. A clear understanding of the scientific principles of the biosimilar concept and access to unbiased information on licensed biosimilars are important for physicians to make informed and appropriate treatment choices for their patients. This will become even more important with the advent of biosimilar monoclonal antibodies. The issues also highlight the need for improved communication between physicians, learned societies, and regulators.

Estradiol inhibits hyaluronic acid synthase 1 expression in human vascular smooth muscle cells.

Epidemiological and clinical data suggest that estrogen retards the progression of atherosclerosis. This study aims to elucidate whether the phenotypic regulation of human vascular smooth muscle cells (VSMC) by estrogen may involve effects on the hyaluronan matrix. VSMC were synchronized by serum withdrawal and subsequently stimulated with 0.001, 0.01, 0.1 and 1 µM estradiol (E(2)) in the presence or absence of platelet-derived growth factor BB (PDGF-BB) for 24 h. E(2) reduced mRNA-expression of hyaluronic acid synthase (HAS) 1 in the presence and absence of PDGF-BB. In contrast, HAS2- and HAS3-mRNA-expression were not affected. This E(2)-mediated effect on HAS1 mRNA-expression was accompanied by reduced hyaluronan secretion and a shift of HA toward lower molecular weight as evidenced by molecular sieve chromatography. The downregulation of HAS1 was abrogated by the estrogen receptor (ER) α and ß antagonist ICI182780 and could be mimicked by the ERα-agonist propyl-pyrazole triol (PPT). On the contrary, the ERß-agonist diarylpropionitrile (DPN) had no effect on HAS1 mRNA-expression. To investigate whether the downregulation of HAS1 was causally involved in the phenotypic regulation of human VSMC by E(2), lentiviral overexpression of HAS1 was conducted. Overexpression of HAS1 abrogated the inhibition of sustained ERK1/2 phosphorylation and in turn inhibition of DNA-synthesis by E(2). For the first time this study provides strong evidence that HAS1-driven HA-synthesis is a target of E(2) in human VSMC and that E(2) mediates part of its anti-proliferative effects through an ERα-dependent inhibition of HA-synthesis.

Similar biological medicinal products currently licensed in the European union--overview of non-clinical study programs.

In the EU, a regulatory framework has been established which defines general conditions for marketing authorisation approval of similar biological medicinal products (SBMPs). In addition, the framework provides product-class specific recommendations for non-clinical evaluation of specific SBMPs containing as active substance recombinant somatropin, granulocyte-colony stimulating factor (G-CSF), erythropoietin, interferon alpha, insulin or low molecular weight heparins. During the last years, a number of SBMPs have been succesfully licensed in the EU. This article summarizes the non-clinical evaluations performed for these medicinal products and provides a comparison with the current requests for non-clinical evaluation as laid down in the respective EU regulatory guidelines.

Proatherogenic effects of estradiol in a model of accelerated atherosclerosis in ovariectomized ApoE-deficient mice.

Clinical studies revealed unfavorable effects of hormone replacement therapy in postmenopausal women despite strong evidence for vasoprotective effects of estrogen in animal models. Therefore, an attempt was made to address adverse effects of estradiol on atherosclerosis, endothelial function, and thrombosis in a murine model of atherosclerosis. ApoE(-/-) mice were bilaterally ovariectomized (OVX) and substituted with placebo or 17-beta-Estradiol (E(2), 1.1 and 6.6 microg/day) on Western diet for 90 days. Low-dose E(2) (1.1 microg/day) treatment significantly increased atherosclerotic plaque score, whereas high-dose E(2) (6.6 microg/day) reduced aortic plaque burden. The proatherosclerotic effects of low-dose E(2) were associated with decreased total collagen in aortic root lesions and impaired acetylcholine (ACh)-induced vasorelaxation of aortic rings. On the contrary, OVX compared with control reduced atherosclerosis, increased fibrillar collagen and improved endothelial function. The thrombotic response as measured in a photothrombosis model was not significantly altered by E(2) or OVX. Taken together, differential effects on atherosclerosis of the clinical relevant low-dose E(2) compared with high-dose E(2) were demonstrated. Importantly, the presented experimental conditions provide a model to study the untoward vascular effects of E(2) in the context of accelerated and advanced atherosclerosis.

Differential effects of medroxyprogesterone acetate on thrombosis and atherosclerosis in mice.

BACKGROUND AND PURPOSE: The risk for cardiovascular events including venous and arterial disease and stroke is elevated after treatment with estrogen and medroxyprogesterone acetate (MPA) in postmenopausal women. Here, we have investigated the effect of MPA on arterial thrombosis and atherosclerosis in a murine model of atherosclerosis. EXPERIMENTAL APPROACH: Apolipoprotein E (ApoE)-/- mice were bilaterally ovariectomized and treated with placebo, MPA (27.7 microg day(-1)) and MPA + 17-beta-oestradiol (E2; 1.1 microg day(-1)) for 90 days, on a Western-type diet. Thrombotic response was measured in a photothrombosis model, platelet activation by fluorescence activated cell sorting (FACS) analysis (CD62P) and thrombin generation by the endogenous thrombin potential (ETP). Furthermore, aortic plaque burden and aortic root plaque composition were determined. KEY RESULTS: MPA and MPA + E2-treated animals showed an aggravated thrombotic response shown by significantly reduced time to stable occlusion. The pro-thrombotic effect of MPA was paralleled by increased ETP whereas platelet activation was not affected. Furthermore, MPA + E2 reduced the number of cells positive for alpha-smooth muscle actin and increased hyaluronan in the plaque matrix. Interestingly, total plaque burden was reduced by MPA but unchanged by MPA + E2. CONCLUSION AND IMPLICATIONS: Long-term treatment with MPA and MPA + E2 increased arterial thrombosis despite inhibitory effects of MPA on atherosclerosis in ApoE-deficient mice. Increased thrombin formation, reduced smooth muscle content and remodelling of non-collagenous plaque matrix may be involved in the pro-thrombotic effects. Thus, MPA exhibits differential effects on arterial thrombosis and on atherosclerosis.

Effects of selective cyclooxygenase isoform inhibition on systemic prostacyclin synthesis and on platelet function at rest and after exercise in healthy volunteers.

To test the hypothesis that selective inhibition of cyclooxygenase (COX)-2 would result in exercise-induced platelet activation by causing a shift in the endogenous thromboxane (TX)/prostacyclin balance, a double blind, randomized study comparing aspirin (300 mg/d) with rofecoxib (25 mg/d) (cross-over design, 14 days washout between treatments) in n = 10 trained healthy volunteers was carried out. Physical exercise resulted only in a minor platelet activation, as reflected by the expression of basal or ADP-stimulated platelet activation markers or basal plasma concentrations of TXB(2). Aspirin significantly reduced TXB(2) in plasma while rofecoxib significantly increased TXB(2) in urine. Although no increase in systemic prostacyclin concentration was observed, there was a significant exercise-related increase in both platelet cAMP and cGMP without any drug-related effects. It is concluded that, in trained healthy volunteers, selective inhibition of COX-1 (aspirin) or COX-2 (rofecoxib) does not affect systemic prostacyclin synthesis after physical exercise. However, our data do not exclude the possibility that in subjects at risk for atherothrombotic complications (e.g. patients with advanced atherosclerotic disease) COX-2 inhibitors may result in platelet activation by inhibiting endothelial prostacyclin formation.

Selective COX-2 inhibitors and risk of thromboembolic events - regulatory aspects.

In the 1990s, the pharmaceutical industry developed selective COX-2 inhibitors (coxibs) as alternatives to conventional nonsteroidal anti-inflammatory drugs (NSAIDs), with the expectation of similar analgetic and anti-inflammatory efficacy but a reduced risk of adverse gastrointestinal (GI) effects. Marketing authorisation (MA) was granted for rofecoxib and celecoxib as first representatives of this new pharmacological class at the end of the 1990s in the EU. In the following years MAs were granted for the 'second generation' coxibs etoricoxib, parecoxib/valdecoxib and lumiracoxib. However, data from large clinical 'outcome studies' as well as epidemiological data raised concerns about the cardiovascular (CV) safety of the coxibs. In consequence, two comprehensive review processes (referrals) were initiated by the European Medicines Agency (EMEA). As a result, in the EU the use of coxibs has been contraindicated in patients with established coronary heart disease, cerebrovascular disease and peripheral arterial disease and a number of warning statements concerning CV, GI and skin toxicity have been introduced in the coxib product informations. This article provides a description of the regulatory actions taken and discusses some specific aspects of the past and future regulatory assessment of coxibs.