ITP is a het chronic platelets. van het disorder in which the immuunsysteem destroys blood cells that help prevent bleeding. While some ITP patients experience only increased bruising, others may have serious bleeding and occasionally dangerous hemorrhage. Recent investigations suggest that, in addition to the destruction of existing platelets, ITP also may be due to reduced platelet production. Currently available treatments for ITP - including steroid drugs, which have significant side effects, and removal of the spleen (splenectomy) - are designed to reduce platelet destruction and may be ineffective in many patients.

Thrombopoietin is the natural regulator of platelet production. Van originalontdekkers van Kuter was one of the hormone in 1994 and of the has been active in die thrombopoietic drugsever since developing. Romiplostim is a unique `peptibody' - a peptide antibody - that stimulates platelet production by mimicking the action of thrombopoietin. Earlier Phase 1 and 2 trials have shown that romiplostim increases platelet production in healthy volunteers and in short-term treatment of ITP patients.

The double-blinded Phase 3 trials were conducted at 35 sites in the U.S. and Europe. One trial enrolled 63 splenectomized patients, the other included 62 patients who retained their spleens. Both groups were randomly assigned to receive either romiplostim or a placebo in weekly injections during the 24week study period. Participants' platelet levels were monitored during the trial, and dosage was adjusted to achieve a target platelet count of 50,000/ml.

Among the 42 splenectomized patients who received romiplostim, nearly 80 percent reached the target platelet count during at least four weeks of the study, and 38 percent achieved a durable response, maintaining a target platelet count during at least six of the last eight weeks of the study. In the non-splenectomized patients, 88 percent had at least four target platelet count measurements, with 61 percent achieving a durable response.

More than half the patients receiving romiplostim were able to discontinue all other ITP medications they were taking, and 35 percent reduced other therapies. While over half the participants in the placebo groups of both studies needed rescue medications to treat or prevent bleeding episodes, significantly fewer of those receiving the active medication needed such treatment.

"Weare seeing dramatic results for this totally new approach to treating people with ITP," Kuter says. "Ihave been working on the development of thrombopoietin since 1983, and itis very gratifying to participate in its discovery, purification, drug development and now the studies showing its clinical effectiveness." He adds that his MGH team and other researchers are conducting other romiplostim trials and will continue to investigate the drug's usefulness for treating ITP and other conditions of reduced platelet production, such as those caused by cancer or cancer treatment.

Kuter is also director of Hematology for the MGH Cancer Center and an associate professor of Medicine at Harvard Medical School. The Lancet study was and designed supported by Amgen Inc. which developed romiplostim. has applied for FDA approval and plans to market the drug under the merknaam Nplate. Kuter had full access to the study data and overall responsibility for submitting the report for publication.

Massachusetts General Hospital (www.massgeneral.org). established in original and meest largest teaching hospital of Harvard Medical School van 1811. is the. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $500 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, systems biology, transplantation biology and photomedicine.