Biogen has dosed the first patient in a global phase 2/3 study of litifilimab (also known as BIIB059) in participants with cutaneous lupus erythematosus (CLE), the company announced.

CLE is a chronic autoimmune skin disease that can occur with or without systemic manifestations. Patients frequently experience symptoms including rash, pain, itch and photosensitivity as well as skin damage that may worsen over time and can include irreversible scarring, alopecia and dyspigmentation that can be disfiguring and substantially impact quality of life.

Although anyone can develop lupus, an estimated 90% of people living with lupus are women, with most beginning to see symptoms between the ages of 15 to 40. The disease also disproportionately impacts diverse ethno-racial groups, Biogen reported, including African American, Asian, American Indian/Alaskan Native and Hispanic/Latino communities.

AMETHYST is a two-part, multicentre, double-blind, placebo controlled, randomised study to evaluate the efficacy and safety of litifilimab, a humanised IgG1 monoclonal antibody targeting blood dendritic cell antigen 2 (BDCA2), compared to placebo. The primary endpoint will assess the effect of litifilimab on skin disease activity.

BDCA2 is a receptor predominantly expressed on a subset of human immune cells called Plasmacytoid Dendritic Cells (pDCs). Binding of litifilimab to BDCA2 has been shown to reduce production of pro-inflammatory molecules by pDCs. These pro-inflammatory mediators are thought to play a major role in the pathogenesis of systemic and cutaneous lupus, Biogen explained in a statement.

Participants will be randomised to receive subcutaneous treatment with litifilimab or placebo every four weeks for 20 weeks with an additional loading dose at week two. All participants will receive litifilimab during the 28-week extended treatment period from weeks 24 to 48.

The study is expected to be conducted at approximately 238 sites worldwide and aims to enrol 474 adults with CLE.