Monoclonal antibody therapy, conceptual illustration. Monoclonal antibodies are monospecific antibodies that have an affinity for the same antigen. Abbreviated 'mab', the drugs derived from them often have names ending in 'zumab' (bottle at left). An antibody molecule (y-shaped) is shown at right. Antibody designs for molecular therapy form the basis of drugs (including cancer drugs) that are worth billions of US dollars per year.