Alexion Pharmaceuticals Inc has commenced its first Phase IIb trial in rheumatoid arthritis patients with its humanized monoclonal antibody C5 complement inhibitor, 5G1.1. The trial is designed to assess the safety and efficacy of 5G1.1 and to confirm the most efficacious dose regimen of the drug.

This double-blind, randomized, placebo-controlled Phase IIb trial is expected to enroll approximately 300 patients with mild to moderate disease undergoing treatment with moderate doses of methotrexate or leflunomide.

The trial will consist of three treatment arms. Patients will be treated with placebo; 5G1.1 at 8 mg/kg intravenous injection once per week for four weeks and then once every month (Induction/monthly); or 5G1.1 at 8 mg/kg intravenous injection once per week for four weeks and then once every two weeks (Induction/biweekly). The patients will be evaluated after a six month drug phase for safety and efficacy, and the primary efficacy endpoint will be the ACR20 score.

``The commencement of this first 5G1.1 Phase IIb trial is an important step in the development of this promising drug candidate,'' stated Leonard Bell, President and Chief Executive Officer of Alexion. ``We seek to confirm the promising clinical data obtained in our earlier 5G1.1 rheumatoid arthritis study in this larger patient study. Importantly, we also seek to build on the durability of response observed in the previous study which evaluated patients after three months of treatment by administering 5G1.1 for a six month period in this Phase IIb trial.''

It is estimated that more than two million Americans are affected by rheumatoid arthritis, a disease in which the immune system attacks multiple joints as well as the whole body. This chronic immune attack frequently involves multiple organs in the body leading to the onset of fatigue, severe joint destruction, pain and disfigurement.