Beng H. Chong

Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: report from an international working group

Diagnosis and management of immune thrombocytopenic purpura (ITP) remain largely dependent on clinical expertise and observations more than on evidence derived from clinical trials of high scientific quality. One major obstacle to the implementation of such studies and in producing reliable meta-analyses of existing data is a lack of consensus on standardized critical definitions, outcome criteria, and terminology. Moreover, the demand for comparative clinical trials has dramatically increased since the introduction of new classes of therapeutic agents, such as thrombopoietin receptor agonists, and innovative treatment modalities, such as anti-CD 20 antibodies. To overcome the present heterogeneity, an International Working Group of recognized expert clinicians convened a 2-day structured meeting (the Vicenza Consensus Conference) to define standard terminology and definitions for primary ITP and its different phases and criteria for the grading of severity, and clinically meaningful outcomes and response. These consensus criteria and definitions could be used by investigational clinical trials or cohort studies. Adoption of these recommendations would serve to improve communication among investigators, to enhance comparability among clinical trials, to facilitate meta-analyses and development of therapeutic guidelines, and to provide a standardized framework for regulatory agencies.

International consensus report on the investigation and management of primary immune thrombocytopenia

Previously published guidelines for the diagnosis and management of primary immune thrombocytopenia (ITP) require updating largely due to the introduction of new classes of therapeutic agents, and a greater understanding of the disease pathophysiology. However, treatment-related decisions still remain principally dependent on clinical expertise or patient preference rather than high-quality clinical trial evidence. This consensus document aims to report on new data and provide consensus-based recommendations relating to diagnosis and treatment of ITP in adults, in children, and during pregnancy. The inclusion of summary tables within this document, supported by information tables in the online appendices, is intended to aid in clinical decision making.

Romiplostim or Standard of Care in Patients with Immune Thrombocytopenia

BACKGROUND Romiplostim, a thrombopoietin mimetic, increases platelet counts in patients with immune thrombocytopenia, with few adverse effects. METHODS In this open-label, 52-week study, we randomly assigned 234 adult patients with immune thrombocytopenia, who had not undergone splenectomy, to receive the standard of care (77 patients) or weekly subcutaneous injections of romiplostim (157 patients). Primary end points were incidences of treatment failure and splenectomy. Secondary end points included the rate of a platelet response (a platelet count >50×10(9) per liter at any scheduled visit), safety outcomes, and the quality of life. RESULTS The rate of a platelet response in the romiplostim group was 2.3 times that in the standard-of-care group (95% confidence interval [CI], 2.0 to 2.6; P<0.001). Patients receiving romiplostim had a significantly lower incidence of treatment failure (18 of 157 patients [11%]) than those receiving the standard of care (23 of 77 patients [30%], P<0.001) (odds ratio with romiplostim, 0.31; 95% CI, 0.15 to 0.61). Splenectomy also was performed less frequently in patients receiving romiplostim (14 of 157 patients [9%]) than in those receiving the standard of care (28 of 77 patients [36%], P<0.001) (odds ratio, 0.17; 95% CI, 0.08 to 0.35). The romiplostim group had a lower rate of bleeding events, fewer blood transfusions, and greater improvements in the quality of life than the standard-of-care group. Serious adverse events occurred in 23% of patients (35 of 154) receiving romiplostim and 37% of patients (28 of 75) receiving the standard of care. CONCLUSIONS Patients treated with romiplostim had a higher rate of a platelet response, lower incidence of treatment failure and splenectomy, less bleeding and fewer blood transfusions, and a higher quality of life than patients treated with the standard of care. ( ClinicalTrials.gov number, NCT00415532.).

HEPARIN-INDUCED THROMBOCYTOPENIA: ASSOCIATION OF THROMBOTIC COMPLICATIONS WITH HEPARIN-DEPENDENT IgG ANTIBODY THAT INDUCES THROMBOXANE SYNTHESIS AND PLATELET AGGREGATION

Abstract Eleven patients in whom thrombocytopenia developed during heparin therapy were studied. Six patients (group 1) had severe thrombocytopenia with delayed onset and five of these patients had thromboembolic complications. A serum factor which induced heparin-dependent thromboxane B 2 synthesis, 14 C-serotonin release, and platelet aggregation was found in all patients in group 1. The serum factor was shown to be IgG. These findings suggest that the mechanism of the severe thrombocytopenia secondary to heparin therapy is immunological and the associated thromboembolic complications may be attributed to in-vivo activation of the platelet prostaglandin pathway and platelet aggregation induced by the heparin-dependent antibody. The five patients in group 2 had mild symptomless thrombocytopenia with early onset. In this group, the heparin-dependent antibody was not found and the mechanism of the thrombocytopenia is probably a direct action of heparin on platelets.

Heparin-induced thrombocytopenia: mechanism of interaction of the heparin-dependent antibody with platelets.

The interaction of the heparin‐dependent antibody with heparin and platelets has been studied using the sera and purified IgG of four patients with heparin‐induced thrombocytopenia. Both normal platelets and Bernard‐Soulier syndrome (BSS) platelets which lack glycoprotein (GP) Ib, GPV and GPIX, aggregated in response to patient serum or IgG, but only in the presence of heparin. A monoclonal antibody (Mab) against platelet Fc II receptor (IV. 3) strongly inhibited the heparin‐dependent aggregation of both normal and BSS platelets induced by patient sera/IgG. Inhibition by the anti‐GPIb Mab (AK2) was variable and occurred only with normal platelets. Anti‐GPIX Mab (FMC 25) was not inhibitory with either normal or BSS platelets. Similar results were obtained using 14C‐serotonin release instead of platelet aggregation as a measure of platelet activation. These findings suggest that (1) the reaction of the heparin‐dependent antibody with platelets and heparin is mediated by a Fc‐dependent mechanism, (2) GPIb, GPV and GPIX are not involved in this reaction, and (3) the inhibitory effect of anti‐GPIb Mab on normal platelets is due to steric interference consistent with the platelet Fc receptor being in close proximity to GPIb.

Hematologic correlates of left atrial spontaneous echo contrast and thromboembolism in nonvalvular atrial fibrillation

OBJECTIVES This study examined the relation between left atrial spontaneous echo contrast, hematologic variables and thrombo-embolism in patients with nonvalvular atrial fibrillation. BACKGROUND Left atrial spontaneous echo contrast is associated with left atrial stasis and thromboembolism in patients with nonvalvular atrial fibrillation. However, its hematologic determinants in patients with nonvalvular atrial fibrillation are unknown. METHODS Clinical, hematologic and echocardiographic variables were prospectively measured in 135 consecutive patients with nonvalvular atrial fibrillation undergoing transesophageal echocardiography. RESULTS Patients with left atrial spontaneous echo contrast (n = 74, 55%) had an increased fibrinogen concentration (p = 0.029), platelet count (p = 0.045), hematocrit (p = NS) and left atrial dimension (p = 0.005). Multivariate analysis showed that left atrial spontaneous echo contrast was independently related to hematocrit (odds ratio = 2.24, p = 0.002), fibrinogen concentration (odds ratio = 2.08, p = 0.008) and left atrial dimension (odds ratio = 1.90, p = 0.004) but not platelet count. It was also associated with left atrial thrombus (n = 15, p = 0.001) and with recent embolism (n = 40, p < 0.001). In 40 clinically stable outpatients without previous embolism, left atrial spontaneous echo contrast was significantly related to hematocrit (p = 0.005), fibrinogen concentration (p = 0.035) and left atrial dimension (p = 0.029) but not to coagulation factor VII, D-dimer, erythrocyte sedimentation rate, platelet count, plasma beta-thromboglobulin, plasma glycocalicin or glycocalicin index. CONCLUSIONS Left atrial spontaneous echo contrast in patients with nonvalvular atrial fibrillation is independently related to hematocrit, fibrinogen concentration and left atrial dimension, indicating a relatively hypercoagulable state in addition to stasis. These findings support the hypothesis that left atrial spontaneous echo contrast is due to erythrocyte aggregation. Hematologic factors may contribute to its association with thromboembolism.

Factors at Admission Associated With Bleeding Risk in Medical Patients: Findings From the IMPROVE Investigators

BACKGROUND Acutely ill, hospitalized medical patients are at risk of VTE. Despite guidelines for VTE prevention, prophylaxis use in these patients is still poor, possibly because of fear of bleeding risk. We used data from the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) to assess in-hospital bleeding incidence and to identify risk factors at admission associated with in-hospital bleeding risk in acutely ill medical patients. METHODS IMPROVE is a multinational, observational study that enrolled 15,156 medical patients. The in-hospital bleeding incidence was estimated by Kaplan-Meier analysis. A multiple regression model analysis was performed to identify risk factors at admission associated with bleeding. RESULTS The cumulative incidence of major and nonmajor in-hospital bleeding within 14 days of admission was 3.2%. Active gastroduodenal ulcer (OR, 4.15; 95% CI, 2.21-7.77), prior bleeding (OR, 3.64; 95% CI, 2.21-5.99), and low platelet count (OR, 3.37; 95% CI, 1.84-6.18) were the strongest independent risk factors at admission for bleeding. Other bleeding risk factors were increased age, hepatic or renal failure, ICU stay, central venous catheter, rheumatic disease, cancer, and male sex. Using these bleeding risk factors, a risk score was developed to estimate bleeding risk. CONCLUSIONS We assessed the incidence of major and clinically relevant bleeding in a large population of hospitalized medical patients and identified risk factors at admission associated with in-hospital bleeding. This information may assist physicians in deciding whether to use mechanical or pharmacologic VTE prophylaxis.

Predictive and Associative Models to Identify Hospitalized Medical Patients at Risk for VTE

BACKGROUND Acutely ill hospitalized medical patients are at risk for VTE. We assessed the incidence of VTE in the observational International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) study and derived VTE risk assessment scores at admission and associative VTE scores during hospitalization. METHODS Data from 15,156 medical patients were analyzed to determine the cumulative incidence of clinically observed VTE over 3 months after admission. Multiple regression analysis identified factors associated with VTE risk. RESULTS Of the 184 patients who developed symptomatic VTE, 76 had pulmonary embolism, and 67 had lower-extremity DVT. Cumulative VTE incidence was 1.0%; 45% of events occurred after discharge. Factors independently associated with VTE were previous VTE, known thrombophilia, cancer, age > 60 years, lower-limb paralysis, immobilization ≥ 7 days, and admission to an ICU or coronary care unit (first four were available at admission). Points were assigned to each factor identified to give a total risk score for each patient. At admission, 67% of patients had a score ≥ 1. During hospitalization, 31% had a score ≥ 2; for a score of 2 or 3, observed VTE risk was 1.5% vs 5.7% for a score ≥ 4. Observed and predicted rates were similar for both models (C statistic, 0.65 and 0.69, respectively). During hospitalization, a score ≥ 2 was associated with higher overall and VTE-related mortality. CONCLUSIONS Weighted VTE risk scores derived from four clinical risk factors at hospital admission can predict VTE risk in acutely ill hospitalized medical patients. Scores derived from seven clinical factors during hospitalization may help us to further understand symptomatic VTE risk. These scores require external validation.

DNAzyme targeting c-jun suppresses skin cancer growth

Catalytic DNA molecules that target the transcription factor c-jun inhibit skin cancer growth in mice. Getting Under Cancer’s Skin Summer brings to mind barbecues, baseball, and trips to the local pool. Yet, outdoor fun can be hazardous to one’s health—too much sun exposure can increase the risk of developing skin cancer. Indeed, one in three cancers worldwide is skin-related, and currently available treatments may induce scarring or other toxicities. Cai et al. now report that the DNAzyme Dz13—which targets an mRNA that encodes a cancer-associated transcription factor, c-Jun—inhibits the growth of two common types of skin cancers: basal cell and squamous cell carcinomas. DNAzymes are single-stranded, all-DNA, catalytic molecules that specifically bind and cleave their target RNAs. The authors examined the effects of Dz13, which destroys c-jun mRNA, on animal models of skin cancer. Dz13 inhibited tumor growth, blocked neovascularization, and prevented metastasis in mouse models of skin cancer—effects that were mediated, in part, through the induction of antitumor immunity. Minimal toxicity was observed in Dz13-treated cynomolgus monkeys, minipigs, and rodents, and there were no off-target effects in more than 70 in vitro bioassays. Thus, Dz13 may prove to be a safe, effective therapy for skin cancer. Nonetheless, one is advised to pack the sun block in preparation for extra innings—or a fifth set. Worldwide, one in three cancers is skin-related, with increasing incidence in many populations. Here, we demonstrate the capacity of a DNAzyme-targeting c-jun mRNA, Dz13, to inhibit growth of two common skin cancer types—basal cell and squamous cell carcinomas—in a therapeutic setting with established tumors. Dz13 inhibited tumor growth in both immunodeficient and immunocompetent syngeneic mice and reduced lung nodule formation in a model of metastasis. In addition, Dz13 suppressed neovascularization in tumor-bearing mice and zebrafish and increased apoptosis of tumor cells. Dz13 inhibition of tumor growth, which required an intact catalytic domain, was due in part to the induction of tumor immunity. In a series of good laboratory practice–compliant toxicology studies in cynomolgus monkeys, minipigs, and rodents, the DNAzyme was found to be safe and well tolerated. It also did not interfere in more than 70 physiologically relevant in vitro bioassays, suggesting a reduced propensity for off-target effects. If these findings hold true in clinical trials, Dz13 may provide a safe, effective therapy for human skin cancer.

Heparin‐induced Thrombocytopenia: Effect of Heparin Platelet Antibody on Platelets

Summary. The plasma of two patients with heparin‐induced thrombocytopenia has been shown to cause platelet aggregation in the presence of heparin. The platelet aggregating factor was isolated in the IgG fraction of the patients’sera suggesting that it was an antibody. This heparin anti‐platelet antibody (HAP‐Ab) induced platelet aggregation and release but did not cause platelet lysis, although it fixed complement. Platelet aggregation was inhibited by EDTA and by inactivation of complement. There was a significant production of malondialdehyde (MDA) and thromboxane B2 (TXB2) implying a role of the prostaglandin synthesis pathway in HAP‐Ab induced aggregation. ADP release also appeared to be involved as apyrase blocked aggregation while hirudin, a thrombin inhibitor, had no effect. The thrombotic complications that have recently been reported in patients with heparin‐induced thrombocytopenia may be explained by some effects of HAP‐Ab on platelets, namely: the antibody mediated platelet factor 3 release, prostaglandin endoperoxides and thromboxane A2 (TXA2) production and platelet aggregation in vivo. These HAP‐Ab mediated effects could be inhibited by anti‐platelet drugs such as aspirin, indomethacin and dipyridamole and thus may have therapeutic implications.