Belimumab and Bortezomib Combination Therapy

The combination of belimumab and bortezomib represents a therapeutic approach for treating refractory systemic lupus erythematosus (SLE). This combination has been documented in clinical cases where bortezomib was used as induction therapy followed by belimumab as maintenance therapy. Belimumab is a B-lymphocyte stimulator (BLyS)-specific inhibitor that works by binding to BLyS (also known as BAFF), a cytokine that promotes B cell survival. By inhibiting BLyS, belimumab reduces the survival of B cells, promotes apoptosis, and decreases the differentiation of B cells into immunoglobulin-producing plasma cells. Bortezomib is a proteasome inhibitor that specifically targets the 26S proteasome. It works by inhibiting the chymotryptic-like activity of the 20S core particle of the proteasome, binding to the active site of the threonine hydroxyl group in the β5-subunit, causing accumulation of defective immunoglobulin chains in plasma cells leading to endoplasmic reticulum stress and apoptosis, and suppressing the NF-κB signaling pathway. The combination therapy typically involves using bortezomib as induction therapy to rapidly reduce autoantibody-producing plasma cells, followed by belimumab as maintenance therapy to prevent regeneration of autoreactive B cell clones. This approach has shown promising results in reducing disease activity as measured by SLEDAI-2K scores, increasing complement protein levels, reducing autoantibody levels, and providing sustained clinical remission in refractory SLE cases, particularly with renal and pulmonary manifestations. Belimumab can be administered intravenously or subcutaneously, while bortezomib can be administered subcutaneously or intravenously.