Assessments of antibody biodistribution

Monoclonal antibody (mAb) therapeutics are in use for several disease conditions, and have generally shown excellent clinical benefit, in large part due to their high specificity and affinity for target proteins. As this therapeutic class continues to grow in size, improved understanding of the mechanisms controlling mAb biodistribution and protein binding may be expected to allow better prediction of safety and efficacy. Due to the large size and polarity of antibodies, rates of mAb distribution and elimination are typically much slower than those reported for small molecule drugs. Additionally, high affinity interaction with target proteins will often influence mAb pharmacokinetics, leading to complex, nonlinear tissue distribution and elimination. In this report, we summarize key determinants of mAb disposition, methods for assessing antibody exposure and protein binding, and model-based approaches that may be utilized to predict mAb pharmacokinetics.