Studies examine current treatment standards for patients with clotting disorders

Published on December 11, 2012 at 7:17 AM · No Comments

Studies presented today at the 54th Annual Meeting of the American Society of Hematology (ASH) examine current treatment standards for patients with clotting disorders in an effort to improve outcomes. The studies evaluate long-held treatment standards and whether modifications in intensity and duration of therapy may offer equally effective outcomes while reducing toxicities and relapse rates.

Although significant advances have been made in delivering new and improved therapies for clotting disorders, treatment still presents challenges; patients must balance the burden of therapy and risk of treatment-related bleeding with the threat of potentially life-threatening clotting. The studies presented today examine how simple strategies in the treatment of polycythemia vera (PV) and venous thromboembolism (VTE) may be safe and help produce more effective results in patients with these disorders.

"It is important to constantly evaluate and challenge standard treatment protocols to ensure that we are utililizing the best possible strategies to treat patients with these serious disorders," said Agnes Y. Lee, MD, moderator of the press conference and Medical Director of the Thrombosis Program and Associate Professor of Medicine at the University of British Columbia and Vancouver Coastal Health in Canada. "Additionally, as we are seeing an increasing number of patients who require ongoing, long-term treatment, it is important to find new ways to improve efficacy and lower the risks of potentially life-threatening complications that accompany these aggressive therapies."

This press conference will take place on Saturday, December 8, 2012, at 2:00 p.m. EST.

A Large-Scale Trial Testing the Intensity of Cytoreductive Therapy to Prevent Cardiovascular Events in Patients with Polycythemia Vera (CYTO-PV trial) [Abstract 4]

In the first randomized clinical trial assessing the proper target hematocrit level, or percentage of red blood cells that should be maintained in patients with polycythemia vera (PV), researchers have concluded that the current recommendation to maintain a hematocrit level of less than 45 percent is associated with a lower risk of thrombosis compared with a less aggressive treatment strategy of maintaining a hematocrit level between 45 and 50 percent.

PV is a rare blood disorder that causes the bone marrow to produce too many red blood cells, making the blood much thicker.This can dramatically increase the risk of blood clots such as deep-vein thrombosis (DVT, a blood clot that forms in a vein deep in the legs) or pulmonary embolism (PE, a blood clot in the lung) and cardiovascular events such as heart attack or stroke. Because thrombosis is the most common cause of death in patients with PV, prompt diagnosis and treatment to reduce the thickness of the blood is critical.

Patients with PV usually have elevated hematocrit levels (approximately 50 to 70%, compared with less than 50% in the general population), which puts them at a higher risk of suffering heart attacks, strokes, and DVT/PE than the general population. In order to reduce this risk, a hematocrit level of less than 45 percent is recommended and initially maintained through phlebotomies. If the hematocrit level cannot be reduced through multiple phlebotomies or disease progression is documented, patients receive hydroxyurea or chemotherapy to eliminate the excess red blood cells. While these two treatment strategies have become widely accepted for PV, until recently no prospective randomized clinical trial has confirmed whether tight control of hematocrit levels below 45 percent successfully prevents or reduces blood clots in patients with PV.

In order to assess the efficacy and safety of maintaining a hematocrit level of lower than 45 percent versus a more liberal approach (keeping hematocrit levels between 45 and 50%), investigators from Italy conducted a study comparing the two strategies among 365 patients with newly diagnosed PV. Patients in Arm A were treated aggressively to maintain hematocrit levels at less than 45 percent, while the patients in Arm B were treated to maintain levels between 45 and 50 percent. The primary composite endpoint was major clots, including stroke, heart attack, transient ischemic attacks ("mini strokes"), clots in the veins in the abdomen, DVT or PE, and cardiovascular death.

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