UK drugs giant GlaxoSmithKline has begun dosing patients in a Phase III study assessing the potential of its monoclonal antibody sirukumab as a treatment for giant cell arteritis.

GCA is a disease characterised by inflammation of large and medium sized arteries predominantly in the head and neck that affects people aged 50 years or over. Symptoms include severe headache, visual loss, jaw and muscular pain and possibly permanent sight loss if the condition is left untreated.

The current approach is to give high-dose steroids to reduce inflammation, but over 70% of patients end up experiencing significant side effects such as osteoporosis, cataract, hypertension and type 2 diabetes mellitus because of prolonged use in a cycle of treatment and relapse.

GSK’s study has been designed to evaluate the efficacy and safety of two subcutaneous doses of sirukumab (100mg every two weeks and 50mg every four weeks) alongside a pre-specified tapering dose of prednisone, to determine whether the drug can reduce the duration of steroid treatment typical in clinical practice. 

Sirukumab is an investigational human anti-IL-6 monoclonal antibody that selectively binds with high affinity to the IL-6 cytokine, a naturally occurring protein believed to play a role in autoimmune conditions. The drug is also is in Phase III development for rheumatoid arthritis, under a licensing and co-development collaboration agreement with Janssen Biologics.