Definition

A human immunoglobulin G1 (IgG1) monoclonal antibody directed against the cell surface antigen cluster of differentiation 46 (CD46; membrane cofactor protein; MCP) that can potentially be used as the antibody moiety of a radioimmunoconjugate and/or antibody-drug conjugate (ADC). Upon administration, anti-CD46 monoclonal antibody YS5 specifically targets and binds to a conformational epitope formed within Sushi domains (complement control protein repeats; CCPs) 1 and 2 on the immune modulatory receptor CD46 expressed on certain tumor cells, and is internalized. The conformational epitope on CD46 is highly expressed in multiple tumor cell types while minimally expressed or absent in normal, healthy tissues. CD46 plays a key role in the negative regulation of innate immunity.