An international comparative analysis and roadmap to sustainable biosimilar markets.

Background: Although biosimilar uptake has increased (at a variable pace) in many countries, there have been recent concerns about the long-term sustainability of biosimilar markets. The aim of this manuscript is to assess the sustainability of policies across the biosimilar life cycle in selected countries with a view to propose recommendations for supporting biosimilar sustainability. Methods: The study conducted a comparative analysis across 17 countries from North America, South America, Asia-Pacific, Europe and the Gulf Cooperation Council. Biosimilar policies were identified and their sustainability was assessed based on country-specific reviews of the scientific and grey literature, validation by industry experts and 23 international and local non-industry experts, and two advisory board meetings with these non-industry experts. Results: Given that European countries tend to have more experience with biosimilars and more developed policy frameworks, they generally have higher sustainability scores than the other selected countries. Existing approaches to biosimilar manufacturing and R&D, policies guaranteeing safe and high-quality biosimilars, exemption from the requirement to apply health technology assessment to biosimilars, and initiatives counteracting biosimilar misconceptions are considered sustainable. However, biosimilar contracting approaches, biosimilar education and understanding can be ameliorated in all selected countries. Also, similar policies are sometimes perceived to be sustainable in some markets, but not in others. More generally, the sustainability of the biosimilar landscape depends on the nature of the healthcare system and existing pharmaceutical market access policies, the experience with biosimilar use and policies. This suggests that a general biosimilar policy toolkit that ensures sustainability does not exist, but varies from country to country. Conclusion: This study proposes a set of elements that should underpin sustainable biosimilar policy development over time in a country. At first, biosimilar policies should guarantee the safety and quality of biosimilars, healthy levels of supply and a level of cost savings. As a country gains experience with biosimilars, policies need to optimise uptake and combat any misconceptions about biosimilars. Finally, a country should implement biosimilar policies that foster competition, expand treatment options and ensure a sustainable market environment.

Appropriation of GPIbα from platelet-derived extracellular vesicles supports monocyte recruitment in systemic inflammation.

Interactions between platelets, leukocytes and the vessel wall provide alternative pathological routes of thrombo-inflammatory leukocyte recruitment. We found that when platelets were activated by a range of agonists in whole blood, they shed platelet-derived extracellular vesicles which rapidly and preferentially bound to blood monocytes compared to other leukocytes. Platelet-derived extracellular vesicle binding to monocytes was initiated by P-selectin-dependent adhesion and was stabilised by binding of phosphatidylserine. These interactions resulted in the progressive transfer of the platelet adhesion receptor GPIbα to monocytes. GPIbα+-monocytes tethered and rolled on immobilised von Willebrand Factor or were recruited and activated on endothelial cells treated with TGF-ß1 to induce the expression of von Willebrand Factor. In both models monocyte adhesion was ablated by a function-blocking antibody against GPIbα. Monocytes could also bind platelet-derived extracellular vesicle in mouse blood in vitro and in vivo Intratracheal instillations of diesel nanoparticles, to model chronic pulmonary inflammation, induced accumulation of GPIbα on circulating monocytes. In intravital experiments, GPIbα+-monocytes adhered to the microcirculation of the TGF-ß1-stimulated cremaster muscle, while in the ApoE-/- model of atherosclerosis, GPIbα+-monocytes adhered to the carotid arteries. In trauma patients, monocytes bore platelet markers within 1 hour of injury, the levels of which correlated with severity of trauma and resulted in monocyte clearance from the circulation. Thus, we have defined a novel thrombo-inflammatory pathway in which platelet-derived extracellular vesicles transfer a platelet adhesion receptor to monocytes, allowing their recruitment in large and small blood vessels, and which is likely to be pathogenic.

Platelet microparticles induce angiogenesis and neurogenesis after cerebral ischemia.

Activated platelets shed microparticles, which contain a variety of growth factors central to angiogenesis and neurogenesis. The aim of this study was to explore whether platelet derived microparticles (PMP) can boost endogenous neural stem cells dependent repair mechanisms following stroke in a rat model. To examine the effects of PMP therapy in-vivo, we delivered PMP or vehicle via a biodegradable polymer to the brain surface after permanent middle cerebral artery occlusion (PMCAO) in rats. Rats were tested with the neurological severity score and infarct volumes were measured at 90 days post-ischemia. Immunohistochemistry was used to determine the fate of newborn cells and to count blood vessels in the ischemic brain. The results show that PMP led to a dose dependent increase in cell proliferation, neurogenesis and angiogenesis at the infarct boundary zone and significantly improved behavioral deficits.

Platelet function changes in different cardiac surgery subgroups as evaluated with an innovative technology.

OBJECTIVES: : During cardiac surgery, platelets undergo substantial changes. The purpose of this study was to assess platelet function and compare these changes between different cardiac operations using an innovative technology. METHODS: : Perioperative platelet function was evaluated by the Impact test [cone and plate(let) analyzer (CPA)]. The Impact test yields 2 parameters for platelet function: average size (AS, the mean size of the platelet aggregates) and surface coverage (SC, the percentage of the surface covered by the platelet aggregates), which correspond to platelet aggregation and adhesion. The study groups were compared for platelet function results in various surgery stages and correlation with bleeding. RESULTS: : A significant decrease in surface coverage was detected on establishment of cardiopulmonary bypass, with an increase up to preoperative values at the end of the surgery in all groups. In contrast to operations performed on bypass, in patients operated without cardiopulmonary bypass, the postoperative AS and SC were higher than the preoperative values, 30.4 ± 8.1 µmol versus 23.3 ± 6.9 µmol, P = 0.02 in AS, and 7.6 ± 3.6% versus 5.2 ± 1.8%, P = 0.04 in SC. Preoperative AS and SC were the only parameters significantly (P = 0.01) and linearly (r = 0.6) related to postoperative bleeding. CONCLUSIONS: : Preoperative platelet function, as evaluated by the CPA, is an independent risk factor determining postoperative bleeding. The off-pump patients presented an increased platelet function at the end of surgery, a finding that can imply a higher risk of thrombosis. The impact test appears to be a useful tool to determine perioperative platelet function and help in prediction of postoperative bleeding.

Using cone and plate(let) analyzer to predict bleeding in cardiac surgery.

The cone and plate(let) analyzer is an established method for assessing platelet function. It evaluates adherence of platelets on an extracellular matrix, expressed as a percentage of surface coverage and the average size of the aggregates. The purpose of this study was to determine the applicability of the cone and plate(let) analyzer in monitoring platelet function and predicting postoperative bleeding. The relationship between postoperative bleeding, perioperative platelet function, and other parameters was studied. A significant decrease in surface coverage was detected upon establishment of cardiopulmonary bypass (from 6.9% +/- 3.9% to 4.7% +/- 1.7%) with a return to preoperative values at the end of surgery. Preoperative average size and surface coverage were the only parameters that significantly and linearly correlated with postoperative bleeding. Patients with an aggregate average size < 20 microm(2) had a significantly higher incidence of severe bleeding (> 965 mL) than those with a size > 20 microm(2) (44% vs. 0%), and a higher mean blood loss (908 +/- 322 mL vs. 337 +/- 78 mL). Similar results were obtained for surface coverage < 5%, indicating the predictive value of these parameters. Preoperative platelet function as evaluated by the cone and plate(let) analyzer is an independent risk factor determining postoperative bleeding.

Molecular characterization of a human monoclonal antibody that interacts with a sulfated tyrosine-containing epitope of the GPIb receptor and inhibits platelet functions.

Modification of tyrosine residues in extracellular proteins by a sulfate moity plays an important role in many ligand/receptors interactions. In the present work, we describe a unique human monoclonal antibody, termed Y1-scFv, that is specific for a sulfated epitope in the platelat receptor GPIb. The Y1-scFv single chain antibody (scFv) competes with von Willebrand factor (vWF) for binding to human platelets and thus effectively inhibits platelet aggregation. Limited proteolysis of GPIb molecule, using the endoproteases, mocarhagin and cathepsin G, revealed that a seven amino-acid epitope, Tyr-276 to Glu-282, contains the recognition site for Y1-scFv. This GPIb region contains three sulfated tyrosine residues. Binding studies of Y1-scFv to cells and to synthetic peptides in vitro indicated that of the seven residues comprising the epitope only sulfo-Tyr-276 and adjacent Asp-277 are critical for the interaction. To identify the reciprocal sequences in the antibody that recognize the sulfated epitope, we introduced mutations within the complementary-determining region of the heavy chain (CDR3H) of Y1-scFv (MRAPVI). Arginine residue in the second position was critical for the binding. Moreover, a mutant, containing two sequential arginine residues, in the second and third positions of the CDR3H (MRRPVI), showed a nine-fold increased binding to GPIb. This antibody mutant also demonstrated a significant increase in inhibition of vWF-dependent platelet aggregation and adhesion under flow. In conclusion, this unique antibody and mutants, that recognize a sulfated epitope in GP1b receptor, efficiently inhibited platelet adhesion and aggregation, making it a candidate for a new anti-thrombotic agent.

Platelet function changes as monitored by cone and plate(let) analyzer during beating heart surgery.

BACKGROUND: Off-pump coronary artery bypass (OPCAB) is believed to reduce cardiopulmonary bypass (CPB)-related complications, including platelet damage. A hypercoagulable state instead of coagulopathy has been reported following OPCAB surgeries due to CPB. Whether platelet function is changed when the injurious effect of CPB is eliminated was investigated. METHODS: Platelet function was determined with the cone and plate(let) analyzer (CPA) method. The 2 parameters, average size (AS) and surface coverage (SC) of platelet aggregates, were measured with the CPA method to assess platelet aggregation and adhesion. These parameters were evaluated, and their values were compared at several stages of OPCAB surgery. The correlations of postoperative bleeding with platelet function at different stages of the surgery and with other factors, such as platelet count, hematocrit, and transfusions, were studied. RESULTS: Both AS and SC increased during several stages of the operation, and postoperative values (mean +/- SD) were significantly higher than preoperative values (30.4 +/- 8.1 microm 2 versus 23.3 +/- 6.9 microm 2 for AS [ P =.02] and 7.6% +/- 3.6% versus 5.2% +/- 1.8% for SC [ P =.04]). The mean total bleeding volume was 875 micro 415 mL. Preoperative AS and SC were the only parameters significantly ( P =.01) and linearly ( r = 0.7) related to postoperative bleeding. CONCLUSIONS: An increased platelet function, as determined by the CPA method, is found following OPCAB surgery. This phenomenon is probably at least partially responsible for the thrombogenic state after OPCAB surgery. Lack of platelet injury attributed to CPB may divert the system toward a more thrombogenic state. Preoperative platelet function, as evaluated by the CPA method, is an independent risk factor determining postoperative bleeding.