This prospective observational study was designed to analyze platelet functions across time in 50 patients scheduled for liver transplantation (LT) secondary to decompensated cirrhosis or ...hepatocellular carcinoma. Platelet functions were assessed before LT (pre-LT), one week (D7) and 1 month (D28) after LT. Platelet count significantly increased from pre-LT time to day 28 as well as circulating CD34+hematopoietic stem cells. To avoid any influence of platelet count on assays, platelet function was evaluated on platelet-rich-plasma adjusted to pre-LT platelet count. Although platelet secretion potential did not differ between time-points, as evaluated by the expression of CD62P upon strong activation, platelet aggregation in response to various agonists significantly increased along time, however with no concomitant increase of circulating markers of platelet activation: platelet microvesicles, platelet-leukocyte complexes, soluble CD40L and soluble CD62P. In the multivariate analysis, hepatic function was associated with platelet count and function. A lower platelet aggregation recovery was correlated with Child C score. History of thrombosis or bleeding was associated with respective higher or lower values of platelet aggregation. This longitudinal analysis of platelet functions in LT patients showed an improvement of platelet functions along time together with platelet count increase, with no evidence of platelet hyperactivation at any time-point.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is of crucial importance and remains challenging and relies on platelet functional assays highlighting the presence of ...heparin-dependent platelet-activating antibodies in patient serum or plasma. Platelet functional assays using washed platelets include the
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C-serotonin release assay (SRA), usually described as the gold standard, and the heparin-induced platelet activation assay (HIPA). Since its first comparison with SRA there has been no additional published study regarding HIPA diagnostic performances compared with SRA. Aim of our retrospective study was to compare the concordance between HIPA and SRA in HIT suspected-patients with positive anti-PF4/heparin antibodies between October 2010 and October 2015. Fifty-five HIT-suspected patients who beneficiated from both HIPA and SRA were included. Positive and negative percent agreements were 83.8% (95% CI 68.0–93.8%) and 66.7% (95% CI 41.0–86.7%), respectively. Overall percent agreement was 78.2% (95% CI 65.0–92.2%). Agreement was higher in patients who underwent cardiopulmonary bypass with extracorporeal circulation circuit for cardiac surgery. We also confirm that the use of a minimum of 2 platelet donors to establish positive HIT diagnosis and 4 platelet donors to exclude HIT diagnosis allows obtaining a good agreement with SRA. Although HIPA and SRA were performed with different platelet donors and in different laboratories, HIPA had a good positive agreement with SRA for HIT diagnosis, showing that HIPA is a useful functional assay that does not require radioactivity and could be developed worldwide to improve HIT diagnosis.
Summary Background Several studies have suggested that proton-pump inhibitors (PPIs), mostly omeprazole, interact with clopidogrel efficacy by inhibiting the formation of its active metabolite via ...CYP2C19 inhibition. Whether this occurs with all PPIs is a matter of debate. As rabeprazole is a less potent CYP2C19 inhibitor than other PPIs, we studied the interaction between rabeprazole and the antiplatelet actions and pharmacokinetics of clopidogrel. Aim To demonstrate the non-inferiority of rabeprazole over placebo using change in platelet reactivity index (PRI; vasodilator-stimulated phosphoprotein VASP assay) in a predefined population of good clopidogrel responders. Omeprazole was used as the positive control. Methods In this randomized three-period crossover study in healthy volunteers, 36 healthy men received clopidogrel (75 mg/day for 7 days) with placebo, omeprazole (20 mg/day) or rabeprazole (20 mg/day). Clopidogrel antiplatelet effects and disposition kinetics were assessed on day 7 of combination therapy. Non-inferiority threshold was predefined as an upper limit of the 90% confidence interval for the difference in change in PRI between placebo and rabeprazole of < 10% in good clopidogrel responders. Results In good clopidogrel responders (inhibition of VASP index > 30%), the clopidogrel antiplatelet effect remained non-inferior to placebo during rabeprazole (difference 3.4% –1.7; 8.5) but not omeprazole (difference 7.5% 2.5; 12.6) co-administration. The AUC0–24 and Cmax of active clopidogrel metabolite decreased with both omeprazole and rabeprazole, and conditions of bioequivalence were not met, except for AUC0–24 with rabeprazole. Conclusions Rabeprazole does not interact with clopidogrel to the same extent as omeprazole. However, under our experimental conditions and proton-pump inhibitor doses, there was no significant pharmacodynamic interaction between rabeprazole or omeprazole and clopidogrel, despite a significant decrease in the formation of clopidogrel active metabolite.
Summary Angiogenic cytokines have been shown to influence vessel injury, and platelets represent a disposable circulating pool of angiogenic molecules. In the present study, objectives were to ...determine whether clopidogrel could have a potential effect on levels of circulating biomarkers of angiogenesis and endothelial activation. We explored 28 healthy white male volunteers treated for 7 days with clopidogrel 75 mg/day. We quantified angiogenic growth factors that have been shown to be correlated to cardiovascular risk or endothelial progenitor cell mobilization such as vascular endothelial growth factor (VEGF)-A and its soluble receptor forms VEGFR1 and VEGFR2, placenta growth factor, and stromal cell-derived factor-1. We also quantified soluble E-selectin and von Willebrand factor to evaluate endothelial activation. Blood samples were drawn just before the first clopidogrel intake on day 1, and after the last dosing (day 7). As expected, we observed a decrease in platelet reactivity in response to clopidogrel, confirmed by vasodilator-stimulated phosphoprotein phosphorylation assay. However, the 7-day intake of clopidogrel did not significantly modify the levels of the selected angiogenic factors or biomarkers of endothelial activation. These results show that circulating angiogenic factor level in healthy subjects is not driven by P2Y12 platelet receptor-induced activation and clopidogrel does not modify in a significant way the endothelial activation level.
End-stage renal patients present a high risk of thrombosis and bleeding. Consequently, it is challenging to prevent clotting during hemodialysis. If a contact system induces thrombin generation in ...the extra corporeal circuit, recent data suggest a role of tissue factor (TF) in hemodialysis-associated thrombosis. Using a method of elution, we collected adhering cells to an acrylonitrile membrane layered by polythyleneimine (AN69-ST). Using optic microscopy and flow cytometry, we observed that adherent cells were mainly constituted by activated polymorphonuclear neutrophils (PMNs). Using a sensitive fluorogenic method of thrombin generation, we found that adhering cells triggered thrombin generation in a TF-dependent manner. We next identified the presence of TF mRNA (Q-PCR) in adhering cells. Using immunofluorescence, we observed the presence of TF in PMNs and of TF-decorated neutrophil extracellular traps (NETs). As TF triggers thrombin generation after binding to serine protease FVIIa, we evaluated the effect of an inactivated human recombinant factor VIIa (hrFVIIai) in a sheep model of hemodialysis (HD). One single bolus of hrFVIIai maintained the full patency of the hemodialysis circuit without any measurable systemic anticoagulant effect. TF is a promising target for preventing thrombosis during HD.
Abstract End-stage renal patients present high risk of thrombosis and bleeding. Consequently, it is challenging to prevent clotting during hemodialysis. If contact system induces thrombin generation ...in the extra corporeal circuit, recent data suggest a role of tissue factor (TF) in haemodialysis-associated thrombosis. Using a method of elution, we collected adhering cells to an acrylonitrile membrane layered by polythyleneimine (AN69-ST). Using optic microscopy and flow cytometry, we observed that adherent cells were mainly constituted by activated polymorphonuclear neutrophils (PMNs). Using a sensitive fluorogenic method of thrombin generation, we found that adhering cell triggered thrombin generation in a TF-dependent manner. We next identified the presence of TF mRNA (Q-PCR) in adhering cells. Using immunofluorescence, we observed the presence of TF in PMNs and of TF-decorated neutrophil extracellular traps (NETs). As TF triggers thrombin generation after binding to serine protease FVIIa, we evaluated the effect of an inactivated human recombinant factor VIIa (hrFVIIai) in a sheep model of hemodialysis (HD). One single bolus of hrFVIIai maintained full patency of the haemodialysis circuit without any measurable systemic anticoagulant effect. TF is a promising target for preventing thrombosis during HD.
Background: The use of extending half-life (EHL) FVIII or FIX products is today a current strategy in Hemophilia A (HA) patients for improving prophylaxis and reducing the number of IV injections. Fc ...fusion technology is based on the use of the neonatal Fc receptor and endogenous Fc recycling pathway, thereby prolonging the half-life (T1/2) of rFVIII-Fc. A single dose phase 1/2 pharmacokinetic (PK) study performed in 16 severe HA patients demonstrated a prolonged T ½ of rFVIII-Fc equal to 18.8 hours (mean) compared to 12.2 hours with one conventional rFVIII (Malhangu et al. Blood 2014).
The aim of the present study was to analyze PK data collected with Elocta® in “real life” i.e. in a large cohort of patients treated in 13 different French hemophilia care centers, and results were compared to those obtained with conventional FVIII, when available. Importantly, this study was performed without any involvement of Sobi, the pharmaceutical company that provides Elocta® in France.
Patients and methods: 113 severe Hemophilia A (HA) patients with the following characteristics were included: mean age 30 years (range 3 - 70); weight 65 Kg (17-125); total FVIII-Fc dose injected 2650 IU (500-5750); FVIII-Fc IU/Kg: 41 (25 - 59); VWF Ag 98% (41-279). The FVIII recovery (R) was calculated as follows: (body weight (Kg) x observed increased in FVIII (%))/administered dose (IU/Kg). The T1/2 was calculated with the following formula: Ln2/((Ln FVIII% T1 - Ln FVIII%T2)/T2 - T1)), with T1 ≥ 4 hours and T2 ≥ 24 hours.
Results were compared to those performed with conventional FVIII (non EHL-FVIII) in 48 patients (Advate® n = 14, Refacto® n = 2, Helixate®/Kogenate®/Kovaltry® n = 29, Factane® n = 3)
Results: rFVIII-Fc activity measured by one stage clotting assay (OSA) was 20% lower than those obtained with chromogenic assay (CSA) in samples with FVIII levels higher than 20%, but this difference was lower than 10% when FVIII levels < 20%. Therefore, rFVIII-Fc recovery (R) always appeared lower when measured with OSA (Mean 2.38, range 1.33 - 5.7) than with CSA (mean 2.82, ranges 1.35 - 5.5) (p < 0.0001). No correlation was found between this recovery and age, weight, injected doses or VWF Ag levels. Mean T1/2 measured with rFVIII-Fc equaled 15 hours whatever the measurement method used (OSA or CSA), and was strongly correlated with vWFAg levels (R2 = 0.57). Using OSA, significantly lower recovery (1.86 vs. 2.49, p = 0.0002) and T1/2 values (11.75 vs. 15.13 hours, p = 0.0004) were measured in children (< 10 years, n = 19) compared to adults. Similar differences were evidenced with data obtained by CSA (recovery : 2.26 vs. 2.93, p = 0.0009 and T1/2 : 11.4 vs. 15.6 h, p = 0.004, n = 14 children < 10 years).
PK parameters of FVIII-Fc were compared to those obtained with non EHL-FVIII (rFVIII or pdFVIII) in 47 patients (mean T1/2 equal to 10.0 hours; range 5.3 - 21.2), and half-lives of these two categories of products were well correlated (r2 = 0.57). However, the apparent benefit provided by FVIII-Fc was variable from one patient to another, with a mean T1/2 rFVIII-Fc / T1/2 FVIII ratio ranging from 0.6 to 2.4 (mean 1.4). Interestingly, the increase in T1/2 with FVIII-Fc was lower than 20% only in patients previously treated with BHK-derived rFVIII i.e. Helixate®/Kogenate®/ Kowaltry® (n=10). Whatever the FVIII injected (FVIII-Fc or other non EHL-FVIII), the T1/2 measured was also strongly correlated to vWF levels, which were significantly lower in patients for whom the mean T1/2 rFVIII Fc / T1/2 FVIII ratio was > 1.3 (mean 79% vs 116% in the others, p=0.017).
Conclusion: This study is the first to report PK data obtained with rFVIII-Fc (Elocta®) in a large group of HA patients. Our results confirm the benefit of rFVIII-Fc in most HA patients, adults or children, but also emphasize the impact of vWF on half-life of rFVIII-Fc or conventional non EHL-FVIII. Indeed, the benefit of rFVIII-Fc clearly appears higher in patients with lower vWF levels, with a more significant prolongation of T1/2.
No relevant conflicts of interest to declare.
The use of enhanced half‐life (EHL) FVIII has improved the quality of prophylaxis in haemophilia A, but with a benefit that may vary from one patient to another. We analysed the pharmacokinetic data ...obtained with efmoroctocog alfa (rFVIII‐Fc) in 114 patients and, in 47 cases, compared them to those previously measured with non‐EHL FVIII. The in vivo recovery (IVR) of rFVIII‐Fc measured with one stage clotting assay (OSA) and chromogenic assay (CSA) was 2.2 and 2.8 IU/mL per IU/kg, respectively. The median half‐life (T1/2) of rFVIII‐Fc was 14.5 hours whatever the FVIII:C assay used, but variable and correlated with preinfusion VWF:Ag levels (r = .76). Both IVR and T1/2 were lower in patients under 12 years old (2.4 IU/mL per IU/kg and 11.1 hours, respectively; CSA). PK study of rFVIII‐Fc vs non‐EHL FVIII showed a T1/2 ratio of 1.4 in favour of rFVIII‐Fc, regardless of the patient's age. However the relative increase in T1/2 with rFVIII‐Fc was lower than 30% in one‐third of patients evaluated, particularly when the previous FVIII administered was a BHK‐derived product. This study therefore suggests that analysis of individual PK profile in response to a specific FVIII concentrate is potentially useful before a switch in haemophilia A patients.
Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is of crucial importance and remains challenging and relies on platelet functional assays highlighting the presence of ...heparin-dependent platelet-activating antibodies in patient serum or plasma. Platelet functional assays using washed platelets include the
C-serotonin release assay (SRA), usually described as the gold standard, and the heparin-induced platelet activation assay (HIPA). Since its first comparison with SRA there has been no additional published study regarding HIPA diagnostic performances compared with SRA. Aim of our retrospective study was to compare the concordance between HIPA and SRA in HIT suspected-patients with positive anti-PF4/heparin antibodies between October 2010 and October 2015. Fifty-five HIT-suspected patients who beneficiated from both HIPA and SRA were included. Positive and negative percent agreements were 83.8% (95% CI 68.0-93.8%) and 66.7% (95% CI 41.0-86.7%), respectively. Overall percent agreement was 78.2% (95% CI 65.0-92.2%). Agreement was higher in patients who underwent cardiopulmonary bypass with extracorporeal circulation circuit for cardiac surgery. We also confirm that the use of a minimum of 2 platelet donors to establish positive HIT diagnosis and 4 platelet donors to exclude HIT diagnosis allows obtaining a good agreement with SRA. Although HIPA and SRA were performed with different platelet donors and in different laboratories, HIPA had a good positive agreement with SRA for HIT diagnosis, showing that HIPA is a useful functional assay that does not require radioactivity and could be developed worldwide to improve HIT diagnosis.
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