CD257 antibodies—also termed B-cell activating factor (BAFF) inhibitors—are engineered biologics that neutralize soluble BAFF, a master cytokine driving B-cell survival and autoantibody production. Their clinical relevance has widened from rare autoimmune disorders to broader immunology portfolios, making them a strategic growth node for global biopharma. The CD257 Antibody market size is valued at USD 2.4 billion in 2025 and is projected to expand at an 8.2% CAGR through 2033, underpinned by label extensions in lupus nephritis, Sjögren’s syndrome, and off-label usage in refractory rheumatoid arthritis. This growth outlook is amplified by precision-dosing algorithms, companion diagnostics, and accelerated regulatory pathways in the U.S., EU, and Japan, collectively reinforcing a robust market forecast and sustained industry expansion.