The U.S. Food and Drug Administration (FDA) approved the drug Nplate™, an engineered therapeutic fusion protein, for the treatment of patients with chronic idiopathic, or immune, thrombocytopenic purpura (ITP). Chronic ITP occurs mainly in adults and is associated by low platelet counts that can result in a range of bleeding symptoms, from bleeding gums, bruising and nosebleeds to heavy menstrual periods and life-threatening hemorrhaging. Nplate™ is manufactured by Amgen, Inc., a pharmaceutical company based in Thousand Oaks, CA.
ITP is an autoimmune disorder in which the immune system destroys platelets, reducing their numbers to the point where blood clotting becomes compromised. In many of these patients, the bone marrow, another source of platelet production, is not able to make up the shortfall adequately. Nplate™, a peptibody protein with attributes of both peptides and antibodies, offsets this deficiency by directly stimulating bone marrow production of additional platelets.
Nplate™ has been FDA-approved exclusively for chronic ITP patients who do not respond to existing therapies, such as the use of corticosteroids and immunoglobulin, and in some cases, splenectomy (removal of the spleen). This approval is based on two randomized clinical trials of approximately 125 patients who were previously treated with at least one of these therapies. The response rate was 85%; patients’ bodies were able to raise and sustain platelet counts during the six-month study.
“This product is important in that it offers a new approach to the treatment of patients with an uncommon blood disorder who are often very ill,” said Janet Woodcock, MD, director of the FDA’s Center for Drug Evaluation and Research. Until now, there have been limited options and no products approved for long-term use.
Side effects of Nplate™ include fibrous deposits in bone marrow and precipitous drops in the platelet count when the medication was stopped suddenly. Some patients developed blood clots.
Source: FDA news release dated August 22, 2008