Stratifying primary Sjögren's syndrome: killers in the balance?

The article by Seror et al. in Arthritis Research & Therapy reports data from the 15 French patients in the open-label BELISS (Efficacy and Safety of Belimumab in Subjects With Primary Sjögren's Syndrome, NCT01160666) study of belimumab in primary Sjögren's syndrome. The study identifies that higher baseline levels of natural killer cells in the peripheral blood and salivary glands are associated with non-response to belimumab therapy. Although caution is required given the open-label nature of the trial, this study adds to data already suggesting a role for natural killer cells in primary Sjögren's syndrome and, importantly, indicates a need for therapeutic stratification.