TNFSF13B and anti-neutrophil cytoplasmic antibody-associated vasculitis: Failure to demonstrate a reduction of relapse risk with belimumab a BLyS inhibitor in the Efficacy and Safety of Belimumab and Azathioprine for Maintenance of Remission in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis (BREVAS) Trial was linked to issues of trial design and a low event rate in the placebo group [53], but the potential for a synergistic B-cell depleting effect when belimumab is combined with rituximab from remission induction is being studied in the Randomised study of rituximab and belimumab sequential therapy in PR3 ANCA-associated vasculitis (COMBIVAS) [54].