Etanercept (ETN) (Enbrel®) is a soluble protein that binds to, and specifically 
inhibits, tumor necrosis factor (TNF), a proinflammatory cytokine. ETN is 
synthesized in Chinese hamster ovary cells by recombinant DNA technology as a 
fusion protein, with a fully human TNFRII ectodomain linked to the Fc portion of 
human IgG1. Successful manufacture of biologics, such as ETN, requires 
sophisticated process and product understanding, as well as meticulous control 
of operations to maintain product consistency. The objective of this evaluation 
was to show that the product profile of ETN drug substance (DS) has been 
consistent over the course of production. Multiple orthogonal biochemical 
analyses, which included evaluation of attributes indicative of product purity, 
potency, and quality, were assessed on >2,000 batches of ETN from three sites of 
DS manufacture, during the period 1998-2015. Based on the key quality attributes 
of product purity (assessed by hydrophobic interaction chromatography HPLC), 
binding activity (to TNF by ELISA), potency (inhibition of TNF-induced apoptosis 
by cell-based bioassay) and quality (N-linked oligosaccharide map), we show that 
the integrity of ETN DS has remained consistent over time. This consistency was 
maintained through three major enhancements to the initial process of 
manufacturing that were supported by detailed comparability assessments, and 
approved by the European Medicines Agency. Examination of results for all major 
quality attributes for ETN DS indicates a highly consistent process for over 
18 years and throughout changes to the manufacturing process, without affecting 
safety and efficacy, as demonstrated across a wide range of clinical trials of 
ETN in multiple inflammatory diseases.