Cells and cell-derived reagents form the basis of an operationally challenging class of test methods used in execution of product potency testing (stability and lot release), assessments of pharmacokinetic/ pharmacodynamic (PK/PD) profiles, detection of antidrug antibodies (ADAs) or neutralizing antibodies (NAB), and characterization and comparability testing of biopharmaceutical products. Frequently, cell-based assays provide the only measurement of the tertiary/quaternary structure of each batch of product at the time of lot release and during stability testing to assist in determining product…