Development of high-affinity binding interactions and utilization of the appropriate tools for affinity determination are the ultimate goals of antibody therapeutic R&D. The expansion of protein engineering methods has provided powerful techniques for affinity maturation of biotherapeutics to accomplish at least part of this goal. In particular, the recent use of phage display methods for antibody affinity evolution have produced high affinity antibodies in the picomolar dissociation constant (KD) range, also with high specificity, such as the TNF-α inhibitor Humira® (AbbVie Inc.)1,2