Biogen Idec, Inc. and PDL BioPharma, Inc. (PDL) announced that the ongoing CHOICE trial, a phase 2, randomized, double-blind, placebo-controlled trial of daclizumab, met its primary endpoint in relapsing multiple sclerosis (MS) patients being treated with interferon beta. Patients receiving daclizumab 2 mg/kg subcutaneously every 2 weeks showed a significant reduction in the number of new or enlarged gadolinium-contrast-enhancing lesions (Gd-CELs) at week 24.

Daclizumab is a humanized monoclonal antibody that targets the IL-2 receptor on activated T cells. Study results will be submitted for presentation at an upcoming medical meeting later this year. Based on a joint review of the 24-week data, the companies plan to initiate a Phase 2 monotherapy trial of daclizumab, and to advance the overall clinical development program in relapsing MS.

"We are very pleased to see positive results from the first randomized trial of daclizumab in patients with relapsing MS, and we look forward to advancing the clinical development program with our partner and acknowledged leader in the MS field, Biogen Idec," said Mark A. McCamish, M.D., Ph.D., chief medical officer, PDL BioPharma. "While the week 24 data set will be presented later this year, we are planning to move forward with additional development activities, most notably the initiation of the SELECT trial, which will study daclizumab as a single agent in patients with relapsing MS."

"We congratulate PDL on conducting a successful trial of daclizumab in MS," said Al Sandrock, M.D., Ph.D., senior vice president, neurology research and development, Biogen Idec. "Daclizumab represents an exciting opportunity within our growing MS portfolio. We look forward to initiating the SELECT trial and continuing to work closely with our partner, PDL, in advancing this important clinical program."

The adverse event profile observed to date in this study is generally consistent with the safety profile described in the United States (U.S.) prescribing information for daclizumab. Patients are being followed for an additional 48 weeks after the daclizumab treatment period to further assess safety and efficacy.

The CHOICE trial is evaluating the efficacy and safety of daclizumab or placebo added to interferon beta therapy in 230 patients with active MS who were enrolled at study centres in the US and Europe. Patients were randomized to receive daclizumab 2 mg/kg every two weeks, daclizumab 1 mg/kg every four weeks or placebo added to ongoing interferon beta treatment.

PDL and Biogen Idec entered into a collaboration agreement in 2005 to co-develop and commercialize daclizumab in MS and indications other than transplant and respiratory diseases. Under the collaboration, the companies are also co-developing volociximab (also known as M200), an antibody in Phase 2 development for the treatment of various solid tumours.

PDL and Biogen Idec share equally the costs of all development activities and all operating profits for both products within the US and Europe. The companies jointly oversee development, manufacturing and commercialization plans for collaboration products and divide implementation responsibilities to leverage each company's capabilities and expertise. Each party will have co-promotion rights in the US and Europe. Outside the US and Europe, Biogen Idec will fund all incremental development and commercialization costs and pay a royalty to PDL on sales of collaboration products.