ZymoGenetics Inc. and partner Merck Serono have reached agreement with the FDA on a special protocol assessment (SPA) to conduct a pivotal trial of the investigational new drug atacicept for patients with lupus nephritis. This is one of two clinical studies intended to form part of the application for marketing authorization.

The randomized, double-blind placebo-controlled multi-center clinical trial will be conducted at sites in North America, Europe, Latin America, and Asia. It will involve about 200 patients with active lupus nephritis and will be aimed at demonstrating the efficacy and safety of atacicept compared to placebo.

Merck Serono, an affiliate of Merck KGaA, of Darmstadt, Germany, is the study sponsor, but ZymoGenetics will conduct the lupus nephritis study. The companies plan to conduct a second study in patients with general systemic lupus erythematosus, and an SPA review process for that is underway.

Atacicept (formerly TACI-Ig) is being developed for the treatment of autoimmune diseases and B-cell malignancies. It contains the soluble TACI receptor that binds to the cytokines BLyS and APRIL. These cytokines are members of the tumor necrosis factor family that promote B-cell survival and autoantibody production associated with certain autoimmune diseases such as SLE. Current data indicates that levels of BLyS and APRIL are elevated in patients with rheumatoid arthritis, SLE and B-cell malignancies. Atacicept has been shown to affect several stages of B-cell development and may inhibit the survival of cells responsible for making antibodies.