Alnylam Pharmaceuticals, Inc. has announced encouraging results from its ongoing Phase I study of ALN-AT3, a subcutaneously administered, investigational RNAi therapeutic targeting antithrombin, or AT, for the treatment of hemophilia and rare bleeding disorders, or RBD. Specifically, data were presented from the study's second dose cohort in hemophilia subjects (n=3), where subcutaneous administration of ALN-AT3 resulted in an up to 70% knockdown of AT. New results provide initial evidence for potential correction of the hemophilia phenotype associated with ALN-AT3 administration and AT knockdown.

Specifically, ALN-AT3 administration resulted in an increase in thrombin generation of up to 334% and a marked improvement in whole blood clotting. In addition, the most advanced severe hemophilia A subject in the cohort has remained bleed free for 47 days without replacement factor prophylaxis. Finally, ALN-AT3 administration continues to be generally well tolerated.