Obinutuzumab Effectively Depletes Key B-cell Subsets in Blood and Tissue in End-stage Renal Disease Patients

The THEORY study evaluated the effects of single and multiple doses of obinutuzumab, a type 2 anti-CD20 antibody that induces antibody-dependent cell-mediated cytotoxicity and direct cell death, in combination with standard of care in patients with end-stage renal disease. METHODS. We measured B-cell subsets and protein biomarkers of B-cell activity in peripheral blood before and after obinutuzumab administration in THEORY patients, and B-cell subsets in lymph nodes in THEORY patients and an untreated comparator cohort. RESULTS. Obinutuzumab treatment resulted in a rapid loss of B-cell subsets (including naive B, memory B, double-negative, immunoglobulin D(+) transitional cells, and plasmablasts/plasma cells) in peripheral blood and tissue. This loss of B cells was associated with increased B cell–activating factor and decreased CXCL13 levels in circulation. CONCLUSIONS. Our data further characterize the mechanistic profile of obinutuzumab and suggest that it may elicit greater efficacy in indications such as lupus where B-cell targeting therapeutics are limited by the resistance of pathogenic tissue B cells to depletion.