Myelodysplasia syndrome and acute myeloid leukemia in patients with congenital neutropenia receiving G-CSF therapy.

Granulocyte colony-stimulating factor (G-CSF) has had a major impact on management of "severe chronic neutropenia," a collective term referring to congenital, idiopathic, or cyclic neutropenia. Almost all patients respond to G-CSF with increased neutrophils, reduced infections, and improved survival. Some responders with congenital neutropenia have developed myelodysplastic syndrome and acute myeloblastic leukemia (MDS/AML), which raises the question of the role of G-CSF in pathogenesis. The Severe Chronic Neutropenia International Registry (SCNIR), Seattle, WA, has data on 696 neutropenic patients, including 352 patients with congenital neutropenia, treated with G-CSF from 1987 to present. Treatment and patient demographic data were analyzed. The 352 congenital patients were observed for a mean of 6 years (range, 0.1-11 years) while being treated. Of these patients, 31 developed MDS/AML, for a crude rate of malignant transformation of nearly 9%. None of the 344 patients with idiopathic or cyclic neutropenia developed MDS/AML. Transformation was associated with acquired marrow cytogenetic clonal changes: 18 patients developed a partial or complete loss of chromosome 7, and 9 patients manifested abnormalities of chromosome 21 (usually trisomy 21). For each yearly treatment interval, the annual rate of MDS/AML development was less than 2%. No significant relationships between age at onset of MDS/AML and patient gender, G-CSF dose, or treatment duration were found (P >.15). In addition to the 31 patients who developed MDS/AML, the SCNIR also has data on 9 additional neutropenic patients whose bone marrow studies show cytogenetic clonal changes but the patients are without transformation to MDS/AML. Although our data does not support a cause-and-effect relationship between development of MDS/AML and G-CSF therapy or other patient demographics, we cannot exclude a direct contribution of G-CSF in the pathogenesis of MDS/AML. This issue is unclear because MDS/AML was not seen in cyclic or idiopathic neutropenia. Improved survival of congenital neutropenia patients receiving G-CSF therapy may allow time for the expression of the leukemic predisposition that characterizes the natural history of these disorders. However, other factors related to G-CSF may also be operative in the setting of congenital neutropenia. (Blood. 2000;96:429-436)

Pravastatin: an antithrombotic effect independent of the cholesterol-lowering effect.

Lipid-lowering with statins reduces blood thrombogenicity. However, it is unknown whether this is purely due to LDL-cholesterol reduction, or it is related to a statin or agent specific effect. We investigated the relationship between reduction in blood thrombogenicity and the magnitude of low-density lipoprotein cholesterol (LDL-C) during pravastatin therapy. We prospectively followed for 6 months 57 hyperlipidemic patients who initiated therapy with pravastatin, and 36 patients who were randomized into placebo plus diet. Pravastatin-treated patients were grouped according to the LDL-C reduction at 6 months; (i) "adequate LDL-C reduction": LDL-C reduction >30% from baseline or LDL-C<125 mg/dl (n = 38; LDL-C reduction 74 +/- 4 mg/dl; 6-month LDL-C 119 +/- 5 mg/dl); (ii) "inadequate LDL-C reduction": neither of the above criteria (n = 19; LDL-C reduction 31 +/- 5 mg/dl; 6-month LDL-C 158 +/- 6 mg/dl). Placebo patients were divided into those "with LDL-C reduction" (n = 17, mean reduction 21 +/- 5 mg/dl) and those "without LDL reduction" (n = 19). The following parameters were altered at 6 months in both patients with "adequate" and "inadequate" LDL-C reduction: (1) tissue plasminogen activator decreased by 1.4 +/- 0.4 and 1.5 +/- 0.5 ng/ml respectively (p = NS); (2) plasminogen activator inhibitor-1 decreased by 8.7 +/- 2.0 and 10.1 +/- 2.7 ng/ml respectively (p = NS); (3) thrombus formation under dynamic flow conditions decreased by 3.5 +/- 0.9 and 2.8 +/- 1.2 microm2 x 10(3) respectively (p = NS). In contrast, no significant changes from baseline were noted in placebo-treated patients, regardless of their LDL-C reduction category, and multivariate analysis eliminated LDL-C reduction as an independent predictor of reduction in thrombogenicity. Therefore, the reduction in thrombogenicity was not proportional to the magnitude of LDL-C reduction suggesting that a class or agent specific property is primarily responsible for the pro-fibrinolytic/antithrombotic effects observed.

Pravastatin therapy in hyperlipidemia: effects on thrombus formation and the systemic hemostatic profile.

OBJECTIVES: The study sought to determine the effects of lipid-lowering with pravastatin on the systemic fibrinolytic profile and on thrombus formation under dynamic flow conditions. BACKGROUND: Lowering cholesterol (C) decreases clinical events in coronary artery disease (CAD) patients, but an analysis of the effects of lipid-lowering on the entire hemostatic and thrombotic profile has not been conducted. METHODS: We prospectively studied 93 stable patients with untreated low-density lipoprotein cholesterol (LDL-C) >145 mg/dl. The CAD patients received pravastatin, and non-CAD patients were randomized to pravastatin versus placebo (double-blind). Thrombus formation upon an injured vascular surface was assessed in a substudy of 40 patients with a previously validated ex vivo perfusion chamber system. Systemic hemostatic markers and thrombus formation were evaluated at baseline, three and six months. RESULTS: Placebo produced no changes in either the lipid profile, any of the hemostatic markers, or the ex vivo thrombus formation. Both pravastatin groups (CAD and non-CAD) showed decreased LDL-C by 30% within 6 weeks (188 to 126 mg/dl, p < 0.001 vs. baseline), and decreased plasminogen activator inhibitor-1 at 3- and 6-month follow-up compared to baseline (15% to 18% decrease at 3 months and 21% to 23% at 6 months). For the tissue plasminogen activator antigen, CAD and non-CAD groups showed significant decreases at 6 months compared to baseline (10% and 13%, respectively). No significant changes were observed with treatment in d-dimer, fibrinopeptide A, prothrombin fragment F1.2, factor VIIa, von Willebrand factor, or C-reactive protein. Fibrinogen levels were significantly increased at 6 months compared to baseline, though still below the upper normal limit. In the perfusion chamber substudy, there was a decrease in thrombus area in non-CAD patients treated with pravastatin at both 3 and 6 months compared to baseline (by 21% and 34%, respectively). The CAD patients showed decreases in thrombus formation by 13% at 3 months, and by 16% at 6 months. The change in LDL-C- correlated modestly with the change in thrombus formation (r = 0.49; p < 0.01). CONCLUSIONS: Pravastatin therapy significantly decreased thrombus formation and improved the fibrinolytic profile in patients with and without CAD. These early effects may, in part, explain the benefit rendered in primary and secondary prevention of CAD.

Thrombolytic therapy in acute myocardial infarction.

Thrombolytic therapy represents the major advancement for the treatment of acute myocardial infarction (MI) that has been achieved in recent years. Based on the recognition of acute totally occlusive intracoronary thrombosis as the primary cause of ST-elevation MI, thrombolytics were evaluated alone or in combination with antithrombotics for the treatment of acute MI. Streptokinase, APSAC and t-PA were the first "standard" regimens evaluated. The "accelerated" t-PA infusion was introduced as the "gold standard" thrombolytic regimen with the GUSTO trial, and was administered in combination with aspirin and intravenous heparin. Many newer thrombolytics have been developed with the expectation to further decrease acute MI mortality, to decrease bleeding complications or to facilitate drug administration. The introduction of platelet glycoprotein IIb/IIIa inhibitors in clinical pharmacology has added a novel drug category for potential use for primary thrombolysis or in combination with thrombolytics. Conceptualizing thrombolytic and anti-thrombotic combination regimens will optimize treatment of acute MI in the future.