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Alnylam Selects Hemophilia Candidate, Releases Preclinical Data


Alnylam Pharmaceuticals this week announced new preclinical data showing that its investigational RNAi-based treatment for hemophilia, ALN-AT3, could achieve target gene knockdown after subcutaneous administration to both mice and non-human primates.

ALN-AT3 comprises siRNAs targeting antithrombin, an endogenous inhibitor of thrombin generation, delivered using Alnylam's proprietary GalNAc-siRNA conjugate delivery technology. Alnylam said that it had been considering going after another natural anticoagulant protein, protein C, but that antithrombin proved to be the superior target.

According to the new data, which were presented at the World Federation of Hemophilia World Congress in Paris, “ALN-AT3 demonstrated potent activity in both mice and non-human primates, with an ED50 for AT plasma protein knockdown of approximately 1 mg/kg after a single subcutaneous dose,” Alnylam said.

“Studies showed a very durable response, where a single subcutaneous dose of ALN-AT3 achieved nadir knockdown of AT at about day 10, with effects lasting over 25 days,” the company added. “These data support a once-a-week or twice-a-month subcutaneous dosing paradigm.”

“We believe our new results demonstrate key proof of concept with this strategy as administration of ALN-AT3 was shown to improve thrombin generation in animal models of hemophilia,” Alnylam CMO Akshay Vaishnaw said in a statement.

The company said it expects to file an investigational new drug application for ALN-AT3 in 2013.

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