Therapeutic antibodies have captured substantial attention due to the relatively 
high rate at which these products reach marketing approval, and the subsequent 
commercial success they frequently achieve. In the 2000s, a total of 20 
antibodies (18 full-length IgG and 2 Fab) were approved by the Food and Drug 
Administration (FDA) or European Medicines Agency (EMA). In the 2010s to date, 
an additional 3 antibodies (denosumab, belimumab, ipilimumab) have been approved 
and one antibody-drug conjugate (brentuximab vedotin) is undergoing regulatory 
review and may be approved in the US by August 30, 2011. However, a less 
heralded group of antibody-based therapeutics comprising proteins or peptides 
fused with an Fc is following the success of classical antibodies.