Recombinant monoclonal antibodies used to treat cancers were the number 4 best selling class of biologics, with total sales in 2005 estimated at $6.77 billion.

Monoclonal antibodies are antibodies that are all identical clones of a single parent immune cell. They can be developed to bind only to cancer cell-specific antigens and induce an immunological response against target cancer cells.

Monoclonal antibodies comprise one of the fastest growing classes of protein therapeutics and are currently being used and developed to treat a variety of cancers as well as autoimmune diseases, cardiovascular disease, infectious diseases and inflammatory diseases, macular degeneration and cardiac rejection.

In August 2006, the Pharmaceutical Research and Manufacturers of America (PhRMA) reported that U.S. companies had 160 different monoclonal antibodies in clinical trials or awaiting approval by the U.S. Food and Drug Administration.

At present, 18 monoclonal antibodies have been approved by the FDA for various therapies.

Four leading recombinant monoclonal antibodies used to treat various forms of cancer are: