Biological assessment growth assays

Potency of drug candidates is typically assessed in vitro. An appropriate potency assay must be biologically relevant to the clinical indication for which the drug is targeted. For example, the potency of a growth factor whose action is believed to induce proliferation of epithelial cells in vivo would need to be assessed by an in vitro epithelial cell-based proliferation assay. 

Bioassays, receptor assays, and immunoassays are used to measure GH. ° Most bioassays assess GH activity by analyzing a variety of growth-related metabohc changes in hypophysectomized rats or in cell cultures. A relatively simple and convenient bioassay, the Nb2 cell assay, uses cultures of GH-sensitive rat lymphoma cells.These bioassays are used primarily for calibrating GH reference materials or for comparing the biological potency and immunoreactivity of GH fragments and synthetic peptides. Receptor assays have also been applied to the measurement of GH, but their use has been limited to research applications. 

This chapter will attempt to describe the various options available to validate commercial assays used in chug development appropriately to meet the expectations and requirements of each study in which they may be used. In particular, we will examine the use of commercial kits for pharmacodynamic (PD), efficacy and toxicity (biomarkers), and pharmacokinetic (PK) assessments. The PK assessment assays will focus on those molecules that are developed as therapeutic chugs, but which are also compounds that exist endogenously in humans. These chugs are often called new biological entities (NBEs) and examples include growth hormone, insulin, and erythropoietin. 

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