Leanne Rochanda

Eculizumab therapy results in rapid and sustained decreases in markers of thrombin generation and inflammation in patients with PNH independent of its effects on hemolysis and microparticle formation

Paroxysmal Nocturnal Hemoglobinuria (PNH) is a clonal bone marrow disorder which results in the loss of glycosylphosphatidyl inositol (GPI) anchors from cell membranes. As a consequence, membrane inhibitors of complement are lost rendering the cells more susceptible to complement mediated destruction. This results in hemolysis, leukopenia, thrombocytopenia and thrombophilia. Eculizumab, a monoclonal antibody to complement protein 5, has been approved for the treatment of PNH and is associated with a significant reduction in hemolysis, thromboembolic events and fatigue. We prospectively studied the effect of Eculizumab therapy on plasma markers of thrombin generation (D-Dimers, TAT), inflammation (IL-6), soluble P-selectin (sP-selectin), antigenic (TFMP) and functional (fTFMP) tissue factor bearing microparticles and total plasma microparticle ex vivo factor Xa generation (MPFXa) in eleven Eculizumab naive PNH patients. Blood sampling occurred day 1, prior to Eculizumab treatment, then on days 8,15,22,29, 43, 90. Our results demonstrate a statistically significant reduction in D-Dimer, TAT, IL-6, sP-selectin, and TFMP during the induction phase of treatment (day 1-29) which was sustained during the maintenance treatment (day 29-90). Although the serum LDH levels decreased rapidly, there was no correlation between the change in LDH and the markers of thrombin generation and inflammation. Although there was a statistically significant decrease in TFMP, this decrease did not correlate with changes in markers of thrombin generation or inflammation. Ex vivo MPFXa generation did not decrease with Eculizumab treatment suggesting continued microparticle formation despite inhibition of hemolysis. Ex vivo total microparticle FXa generation was found to have an inverse correlation with markers of thrombin generation, suggesting that in PNH patients in vivo thrombin generation occurs by a pathway independent of hemolysis and microparticle generation.

Subclinical haemostatic activation and current surgeon volume predict bleeding with open radical retropubic prostatectomy

To assess subclinical haemostatic activation and clinical variables to predict bleeding during radical retropubic prostatectomy (RP), as haemostatic activation is common in cancer and might be useful for predicting outcomes, but routine coagulation screening does not correlate with bleeding.

Approach to the treatment, characterization and diagnosis of an acquired auto-antibody directed against factors prothrombin, factor X and factor IX: a case report and review of the literature

Summary.  Bleeding disorders secondary to acquired non‐inhibitory antibodies directed against vitamin K‐dependent coagulation proteins are rare. In this report, the authors describe a patient with a low grade lymphoma who presented with a fatal acquired bleeding manifestation and abnormal hemostatic studies resulting from deficiencies in both prothrombin and factor X. Patient plasma samples were collected and studied for the presence of an acquired inhibitor. Levels of plasma coagulation proteins were measured using immunoassay. Patient anti‐prothrombin immunoglobulin G was isolated and binding to prothrombin, prothrombin F1.2, factors IX and X was evaluated using immunoblots and competition immunoassay. Prolongation in the prothrombin time and activated partial thromboplastin time suggested a factor deficiency in the common pathway of coagulation. Functional and antigenic levels of both prothrombin and factor X were decreased. An IgG subtype‐4 antibody was isolated from patient plasma using affinity chromatography on prothrombin‐sepharose. This antibody was found to bind to a common metal‐ion‐dependent conformational epitope found on the γ‐carboxyglutamic acid (Gla) domain of prothrombin, factor X and factor IX. This report represents the first description of an acquired bleeding disorder resulting from a unique cross‐reactive auto‐antibody against a common metal‐ion‐dependent antigenic structure on the Gla‐domain of the vitamin K‐dependent proteins.

OC-14 - Baseline D-dimer levels are predictive of recurrent venous thromboembolism (VTE) at 6 months in cancer patients with VTE treated with tinzaparin

INTRODUCTION VTE is a major complication in cancer patients. Despite treatment with low molecular weight heparin (LMWH), 9% will have recurrent VTE within 6 months. Measurement of plasma biomarkers in cancer patients receiving LMWH may be predictive of recurrent VTE or overall survival (OS). AIM We conducted a single arm phase 2 study to evaluate the efficacy and safety of once daily tinzaparin for the initial treatment and extended prophylaxis of VTE in cancer patients. The study included a prospective analysis of plasma biomarkers D-dimer and IL-6 to assess whether these were predictive of recurrent VTE or OS. MATERIALS AND METHODS Consecutive patients with active cancer diagnosed with a pulmonary embolism (PE) and/or proximal deep venous thrombosis (DVT) at the University of Southern California Norris Comprehensive Cancer Center, Los Angeles County Medical Center, or New York Presbyterian - Weill Cornell Medical Center were invited to participate in this study with a target enrollment of 100 patients. Key eligibility criteria included: age ≥18, ECOG score ≤2, adequate organ function, and ≥6 month estimated survival. Patients were treated with daily subcutaneously tinzaparin 175 U/kg for 6 months on study. Tinzaparin could be continued ≤1 year at the discretion of the treating physician. All patients who received ≥1 dose were evaluable for efficacy and safety. Primary study endpoints were recurrent VTE or major bleeding. Secondary outcome measures included OS and plasma biomarkers. Biomarkers were measured at baseline, 7 days, 1 month and 6 months after tinzaparin initiation. Patients who had baseline and 1 week or 1 month samples collected were included in the biomarker analysis. RESULTS 97 patients were enrolled. 2 patients were ineligible. 8 patients did not have baseline or follow-up biomarkers completed. 87 patients were included in the analysis. 28 (32%) of patients completed≥6 months of tinzaparin. Major bleeding occurred in 2 patients. 11 patients had recurrent VTE at 6 months (3 PE, 7 DVT, 1 central venous thrombosis not associated with a catheter). Median baseline D-dimer level was 2759 ng/mL (range: 375-37,591). Median baseline IL-6 level was 9.4 pg/mL (range: 0.8-20.9). Baseline D-dimer>median was predictive of VTE recurrence at 6 months (p=.006). Baseline IL-6>median was not predictive of VTE recurrence at 6 months. Neither 1 month D-dimer or IL-6 levels were predictive of VTE recurrence at 6 months. D-dimer and IL-6 at baseline and at 1 month were not predictive of OS. CONCLUSIONS In patients with active cancer and VTE treated with tinzaparin, baseline D-dimer levels above the median value were predictive of VTE recurrence at 6 months.

Approach to the treatment, characterization and diagnosis of an acquired auto-antibody directed against factors prothrombin, factor X and factor IX: a case report and review of the literature: AN AUTO-ANTIBODY DIRECTED AGAINST FACTORS II AND X

Summary.  Bleeding disorders secondary to acquired non‐inhibitory antibodies directed against vitamin K‐dependent coagulation proteins are rare. In this report, the authors describe a patient with a low grade lymphoma who presented with a fatal acquired bleeding manifestation and abnormal hemostatic studies resulting from deficiencies in both prothrombin and factor X. Patient plasma samples were collected and studied for the presence of an acquired inhibitor. Levels of plasma coagulation proteins were measured using immunoassay. Patient anti‐prothrombin immunoglobulin G was isolated and binding to prothrombin, prothrombin F1.2, factors IX and X was evaluated using immunoblots and competition immunoassay. Prolongation in the prothrombin time and activated partial thromboplastin time suggested a factor deficiency in the common pathway of coagulation. Functional and antigenic levels of both prothrombin and factor X were decreased. An IgG subtype‐4 antibody was isolated from patient plasma using affinity chromatography on prothrombin‐sepharose. This antibody was found to bind to a common metal‐ion‐dependent conformational epitope found on the γ‐carboxyglutamic acid (Gla) domain of prothrombin, factor X and factor IX. This report represents the first description of an acquired bleeding disorder resulting from a unique cross‐reactive auto‐antibody against a common metal‐ion‐dependent antigenic structure on the Gla‐domain of the vitamin K‐dependent proteins.

Approach to the treatment, characterization and diagnosis of an acquired auto-antibody directed against factors prothrombin, factor X and factor IX

Summary.  Bleeding disorders secondary to acquired non‐inhibitory antibodies directed against vitamin K‐dependent coagulation proteins are rare. In this report, the authors describe a patient with a low grade lymphoma who presented with a fatal acquired bleeding manifestation and abnormal hemostatic studies resulting from deficiencies in both prothrombin and factor X. Patient plasma samples were collected and studied for the presence of an acquired inhibitor. Levels of plasma coagulation proteins were measured using immunoassay. Patient anti‐prothrombin immunoglobulin G was isolated and binding to prothrombin, prothrombin F1.2, factors IX and X was evaluated using immunoblots and competition immunoassay. Prolongation in the prothrombin time and activated partial thromboplastin time suggested a factor deficiency in the common pathway of coagulation. Functional and antigenic levels of both prothrombin and factor X were decreased. An IgG subtype‐4 antibody was isolated from patient plasma using affinity chromatography on prothrombin‐sepharose. This antibody was found to bind to a common metal‐ion‐dependent conformational epitope found on the γ‐carboxyglutamic acid (Gla) domain of prothrombin, factor X and factor IX. This report represents the first description of an acquired bleeding disorder resulting from a unique cross‐reactive auto‐antibody against a common metal‐ion‐dependent antigenic structure on the Gla‐domain of the vitamin K‐dependent proteins.