Monoclonal antibodies are substances produced in a lab that attach to certain proteins in the body (like a key in a lock). The antibodies can boost your body's natural defenses against disease or can be used to kill cancer cells or slow the progress of a disease.

Monoclonal antibodies are given through an intravenous (IV) injection. The antibodies can be used alone, or they can be used to deliver medicine or radiation directly to cancer cells to treat diseases such as leukemia and non-Hodgkin's lymphoma. Also, monoclonal antibodies can slow the progress of a disease by stopping biological processes such as inflammation in rheumatoid arthritis.