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Drug Candidate for TTP Entering Phase 2 Trial

Archemix Corporation, a Cambridge, MA-based biotech company that develops therapies for rare hematological diseases, announced that it has begun a Phase 2 clinical trial for its drug ARC1779 for the treatment of thrombotic thrombocytopenic purpura (TTP), a relatively rare blood disorder caused by the lack of an enzyme needed for blood clotting. The two main characteristics of the disease are purpura, or purple spots on the skin from bleeding under the skin, and low platelet count, or thrombocytopenia. The disease can be inherited or acquired.

In patients with TTP, the coagulation protein von Willebrand factor (VWF) is not adequately regulated, leading to a drop in platelet levels and proliferation of blood clots. These clots form when some of these remaining platelets cling together abnormally and stick to the walls of small blood vessels. By obstructing small blood vessels, the clots limit the flow of blood to vital organs. If left untreated, complications of TTP can include abnormal kidney function, abdominal pain, fever, headaches and confusion. In severe cases, patients can experience brain damage, kidney failure, heart attack, seizure or stroke.

ARC1779 is an aptamer, a nucleic acid macromolecule with a shape that it is well-suited to binding tightly to a specific molecular target–including any number of proteins–for a therapeutic purpose. In this case, ARC1779 is designed to target VWF, inhibiting the protein’s role in platelet activation, adhesion and aggregation.

The purpose of the Phase 2 trial, which is being conducted at the Medical University of Vienna in Austria, is to evaluate the safety, pharmacokinetics and pharmacodynamics (the effects of drugs on the body) of ARC1779 in approximately 28 patients with VWF-mediated platelet function disorders, including acute TTP.

“The initiation of this Phase 2 trial represents an important strategic milestone for Archemix because it demonstrates the continued advancement of our product portfolio of novel aptamer therapeutics for rare hematological diseases,” said Errol DeSouza, PhD, President and Chief Executive Officer of Archemix. “Our emerging pipeline of aptamers for rare hematological conditions includes preclinical programs in sickle cell disease and hemophilia, as well as our clinical programs in TTP and other related platelet-mediated disorders.”

Currently there are no drugs approved to treat TTP. Treatment options include infusions of fresh frozen plasma and plasmapheresis (plasma exchange). According to Archemix, acute episodes of TTP are associated with a mortality rate estimated to be as high as 20%.

Source: Archemix news release dated March 17, 2008