ATLANTA, Dec. 8 /PRNewswire-USNewswire/ -- Data that shed new light on the treatment of residual vein thrombosis, thromboprophylaxis after total hip replacement, chronic immune thrombocytopenic purpura, and venous thrombosis in relation to postmenopausal hormone replacement therapy will be presented at the 49th Annual Meeting of the American Society of Hematology in Atlanta, GA. A press conference will reveal this new research on Saturday, December 8, from 10:00 to 11:00 a.m.
"Complications related to blood clotting and bleeding affect millions of Americans. In this session we will see exciting breakthroughs in the treatment and approach to mitigating the risk of thrombosis and bleeding disorders, which will directly impact the quality of treatment for many patients," said Andrew Schafer, MD, President, American Society of Hematology, and Chairman, Department of Medicine, New York Presbyterian-Weill Cornell Medical Center, New York, NY, who will be moderating the press conference on blood clotting and bleeding disorders.
-- Investigational drug, AMG 531, demonstrates efficacy in sustaining platelet counts in splenectomized patients with chronic immune thrombocytopenic purpura in phase III study [Abstract #2]
Terry Gernsheimer, MD, Puget Sound Blood Center, Seattle, WA
In this randomized, placebo-controlled phase III study, investigators evaluated the efficacy and safety of AMG 531 in previously splenectomized patients with chronic immune thrombocytopenic purpura (ITP) per ASH guidelines and baseline platelet counts <30,000/µL. Chronic ITP is an autoimmune disorder in which patients produce antiplatelet autoantibodies that destroy their blood platelets and, in some cases, damage their megakaryocytes (the cells that produce platelets in the bone marrow) causing defective platelet production. These result in a low blood platelet count that may cause bruising or excessive bleeding. Splenectomy (removal of the spleen) is sometimes undertaken in patients with chronic ITP, as platelets targeted for destruction will often meet their fate in the spleen. Splenectomy is said to be successful in 60 percent of cases although it is less successful in older people. AMG 531 is a novel "peptibody" that acts by stimulating platelet production at the thrombopoietin receptor. Thrombopoietin is a hormone that promotes platelet production by the bone marrow. In this study, subcutaneous AMG 531 or placebo was administered weekly for 24 weeks at a starting dose of 1µg/kg, and adjusted to maintain a target platelet count of 50-200x109/L in the 63 enrolled splenectomized patients with ITP. The results indicated that AMG 531 was well tolerated and effectively increased and sustained platelet counts in patients. AMG 531-treated patients required less frequent rescue medications (medications needed in an emergency to re-stabilize platelet counts and prevent or treat bleeding) in comparison with those receiving the placebo, and were able to reduce their use of concurrent ITP therapies.
-- RECORD1 is the first pivotal trial to demonstrate the efficacy and safety of a fixed, unmonitored dose of an oral, direct Factor Xa inhibitor -- rivaroxaban -- for extended prevention of blood clotting after a total hip replacement [Abstract #6]
Bengt I. Eriksson, MD, PhD, Ortopedkliniken, Sahlgrenska University Hospital/Ostra, Goteborg, Sweden
This multinational, randomized, double-blind, double-dummy phase III trial studied the efficacy and safety of oral rivaroxaban in comparison to subcutaneous enoxaparin to prevent blood clotting (a process known as thromboprophylaxis) for five weeks in patients undergoing a total hip replacement (THA). Thromboprophylaxis is recommended for at least 10 days and for up to four to five weeks after total hip replacement in order to avoid the formation of a thrombembolism, or a clot in a blood vessel that breaks loose and is carried by the blood stream to plug another vessel. This type of clot may cause a number of fatal complications, including blocking a vessel in the lungs (pulmonary embolism) or brain (stroke). Rivaroxaban is an oral, direct Factor Xa inhibitor - the newest class of antithrombotic agents - in advanced clinical development for the prevention and treatment of thromboembolic disorders. Enoxaparin is a traditional blood thinner used to prevent deep vein thrombosis. The study included a total of 4,541 randomized patients who either received rivaroxaban 10 mg beginning six to eight hours after surgery and once daily thereafter, or enoxaparin 40 mg once daily beginning the evening before surgery and restarting six to eight hours following surgery. Results showed that rivaroxaban was significantly more effective than enoxaparin for extended prophylaxis after THA. This is the first pivotal trial to demonstrate the efficacy and safety of a fixed, unmonitored dose of an oral, direct Factor Xa inhibitor for extended thromboprophylaxis patients after THA.
-- Women's Health Initiative evaluates coagulation factors, postmenopausal hormone replacement therapy, and the risk of venous thrombosis [Abstract #127]
Mary Cushman, MD, MSc, University of Vermont, Burlington, VT
This session will present preliminary data from two trials of the Women's Health Initiative on two different estrogen regimens to evaluate coagulation markers as susceptibility factors for postmenopausal hormone-related venous thrombosis (VTE). Postmenopausal estrogen (E) therapy, especially in combination with progestin (P), doubles the relative risk of venous thrombosis (VTE). Risk with hormones is higher with increasing age, obesity, and the presence of factor V Leiden, the most common hereditary blood coagulation disorder in the United States. These two placebo-controlled double-blind randomized trials evaluated two E regimens - E (conjugated equine estrogens) or E+P (E + medroxyprogesterone acetate), in 16,608 postmenopausal women age 50-79. The investigators performed a nested case control study that measured baseline levels of coagulation markers in 215 women who developed VTE during follow-up and 867 age-matched controls. The joint effects of treatment assignment to either E regimen or placebo and prespecified abnormal levels of each coagulation factor on relative risk of VTE were estimated by logistic regression adjusting for age, race, body-mass index, and type of E regimen. The study reported new findings of elevated coagulation markers, F1-2 and PAP, as VTE risk factors in women in this prospective study nested in trials of E or E+P vs. placebo.
Lower levels of other coagulation markers protein C and free protein S and higher D-dimer F1-2 and PAP, all identified women at increased risk of VTE with hormones. If these findings are confirmed in further studies, measurement of these factors might assist women with decision- making on safety of E or E+P.
-- Extended Dacus study indicates that short-term anticoagulation is safe for patients with idiopathic deep vein thrombosis [Abstract #301]
Sergio Siragusa, MD, Istituto di Ematologia Policlinico Universitario di Palermo, Palermo, Italy
This study evaluated whether short-term oral anticoagulation therapy (OAT) is safe for patients with deep vein thrombosis (DVT) after an episode of idiopathic deep vein thrombosis (DVT of an obscure or unknown cause). OAT is a standard treatment for patients who have experienced venous thrombosis. It is used to reduce the risk of recurrent blood clotting and is typically administered using drugs such as warfarin and acenocoumarol. While anticoagulation therapy mitigates some risks for patients, it also increases the risk of major bleeding and therefore raises the question of how long patients can safely receive OAT. Currently, a period of three months is indicated for VT due to transient risk factors (i.e. surgery) while at least three to six months are required for idiopathic DVT. It has already been determined that the optimal duration of OAT for DVT can be tailored according to the presence of residual vein thrombosis (RVT), long-lasting blood clots that remain inside the vein, as RVT serves as a marker to assess the individual risk for recurrent thrombosis. However, in patients with idiopathic DVT who have not demonstrated RVT, the safety of early interruption of OAT is still debated. This prospective controlled study evaluated the safety of withholding OAT in patients with idiopathic DVT and without RVT, three months after the index thrombotic episode. The study evaluated two groups: DVT patients without RVT who stopped OAT after three months and those with RVT who continued OAT for an additional three months. During the period from 1999-2006, 518 patients were included in the study. In 206 patients (39.7 percent), RVT was considered absent (RVT negative group) and OAT was stopped; the remaining 312 patients continued receiving anticoagulants for an additional three months (RVT positive group). The study found that in patients without RVT, three months of OAT was safe even after an episode of idiopathic DVT. This indicates that individual markers for VT, such RVT, may help in the management of VT and can allow OAT duration to be tailored. The RVT finding applies to at least 30 percent of the entire DVT population and has an important clinical impact, indicating that patients at low risk of recurrent thrombosis can now safely withdraw from OAT after three months. This approach also carries a negligible risk for bleeding.
The study authors and press program moderator will be available for interviews after the press program or by telephone. In addition to blood clotting and bleeding disorders, additional press briefings will take place focusing on leukemias, sickle cell disease and thalassemia, hematologic malignancies, and transplantation. For the complete annual meeting schedule and additional information, please visit http://www.hematology.org/meetings/2007.
The American Society of Hematology (http://www.hematology.org) is the world's largest professional society concerned with the causes and treatment of blood disorders. Its mission is to further the understanding, diagnosis, treatment, and prevention of disorders affecting blood, bone marrow, and the immunologic, hemostatic, and vascular systems, by promoting research, clinical care, education, training, and advocacy in hematology.
|SOURCE American Society of Hematology|
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