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.