SAN FRANCISCO – The sequential combination of rituximab followed directly by maintenance belimumab shows considerable promise as a strategy to address the aberrant B-cell immunology present in systemic lupus erythematosus (SLE) – and thereby improve clinical outcomes, Y.K. Onno Teng, MD, PhD, reported at an international congress on systemic lupus erythematosus.
Bruce Jancin/MDedge News
Dr. Y.K. Onno Teng
Dr. Teng, a nephrologist and clinical trialist at Leiden (the Netherlands) University, and his coworkers were pioneers of this one-two punch, in which a two-dose course of rituximab (Rituxan) is given to deplete CD20-positive B-cells, followed by long-term maintenance belimumab (Benlysta) to inhibit repopulation of specific problematic types of B-cells. The rationale for the use of belimumab here lies in the observation that the initial B-cell depletion induced by rituximab triggers a surge in B lymphocyte stimulator (BLyS), which signals the bone marrow to start making more B-cells. And belimumab famously inhibits BLyS, also known as B-cell activating factor, or BAFF.
Dr. Teng presented the 2-year extended results of Synergistic B-cell Immunomodulation in SLE (SYNBIoSe-1), a phase 2a, open-label, single-arm, proof-of-concept study whose 24-week immunologic results have previously been reported (J Autoimmun. 2018 Jul;91:45-54).
Based in part upon the encouraging SYNBIoSe-1 findings as well as the sound mechanistic rationale for this treatment strategy, the combination of rituximab and belimumab is picking up steam in the research world as a potentially important treatment advance in SLE. Currently underway in patients with nonrenal SLE is the phase 3, GlaxoSmithKline-sponsored, global BLISS-BELIEVE trial, as well as the phase 2 BEAT-LUPUS study, a University College London–based randomized trial of rituximab plus either placebo or belimumab. Also, Dr. Teng and his coworkers are now conducting SYNBIoSe-2, in which patients with lupus nephritis are being randomized to standard therapy with glucocorticoids and mycophenolate or to rituximab, belimumab, and mycophenolate.
SYNBIoSe-2 is a further exploration of the encouraging signal of efficacy for lupus nephritis noted in SYNBIoSe-1. Of the 12 participants in SYNBIoSe-1 who had baseline active lupus nephritis, 8 had a positive renal response to the rituximab/belimumab combo, including 6 patients who achieved a prolonged complete renal response through 104 weeks of follow-up.
SYNBIoSe-1 included 15 patients, all with severe refractory SLE as shown by a median 11-year disease duration and a baseline SLE Disease Activity Index score of 18. Two-thirds of patients achieved sustained low-level disease activity, interrupted in one case by a single major disease flare. Two patients stopped treatment because of a lack of response. Several others left the study because they were doing so well on treatment that they decided the time was right to become pregnant.
Immunologically, patients showed an 84% reduction in B-cell repopulation over the course of 2 years. Particularly striking was the long-term inhibition of double-negative B-cells and IgD-positive naive B-cells, which Dr. Teng described as “very trigger happy” in that they readily become transformed into activated antibody-producing cells.
Sustained specific reductions in anti-double-stranded DNA autoantibodies and other pathogenic antinuclear antibodies were also documented through 104 weeks.