Drug Interaction Report

MONITOR: Concomitant use of belimumab and biologic therapies, including B-cell targeted therapies with immunosuppressant effects may lead to an increase in the rate of severe adverse events and serious infections. In a double-blind, randomized, placebo-controlled, phase 3 trial in adults with systemic lupus erythematosus (SLE) receiving belimumab, the addition of rituximab was associated with serious adverse events in 22.2% and serious infections in 9% of patients, compared to 13.9% and 2.8% of patients, respectively, in the placebo add-on group. Clinical data for other B-cell targeted therapies are unavailable.

MANAGEMENT: According to the manufacturer of belimumab, available data do not support the coadministration of belimumab with rituximab in patients with SLE. Caution and monitoring for adverse reactions, particularly infections, is advised if concomitant use of belimumab with other biologic therapies with immunosuppressant effects, particularly B-cell targeted therapies including but not limited to ocrelizumab, ofatumumab, or obinutuzumab. Some authorities advise against their concomitant use.