TKT Achieves GA-GCB Clinical Milestone

Transkaryotic Therapies has announced that the last patient has completed treatment in its open-label Phase I/II clinical trial evaluating its investigational enzyme replacement therapy for Gaucher disease, gene-activated glucocerebrosidase, or GA-GCB.

The Phase I/II clinical trial evaluated the safety of GA-GCB as well as its clinical activity in 12 patients. The company expects to report top-line results of the study in the second half of 2005. Assuming the results are favorable, the company intends to commence a pivotal trial in 2006, designed to support an approval of GA-GCB in 2008.

In March 2005, TKT completed its pivotal clinical trial evaluating its investigational enzyme replacement therapy Iduronate-2-Sulfatase, I2S, for the treatment of Hunter syndrome in 96 patients. The company is currently gathering and verifying the final data and expects to unblind the study and report top-line results in June 2005. If the results are positive, TKT intends to file for regulatory approval in both the U.S. and Europe during the second half of 2005. From May 23 until it reports top-line results, TKT will suspend its investor relations activities.