The Freedom ExpiCHO-S Kit Generates Stable Clones And Delivers Enhanced Productivity

In bioproduction, once the desired therapeutic protein is identified, an expression system capable of generating high-producing stable clones is required to support output and quality requirements for commercial scale-up. The in-house development of cell lines and identification of optimal workflow components and processes can be time-consuming and costly. An optimized and robust commercially available cloning and expression system kit would support streamlining product development to reduce time to market.

The Gibco™ Freedom™ ExpiCHO-S™ Kit was developed with these goals in mind. It provides a cGMP cell line with regulatory-friendly components and royalty-free licensing. Additionally, the kit includes a dual-vector system, Gibco™ Freedom™ pCHOm 3.1 and Freedom™ pCHOp 3.2 (designed by ProBioGen AG), for insertion of genes of interest and control of antibody heavy and light chain ratios.

Studies were conducted to evaluate the capability to generate IgG-producing Gibco™ ExpiCHO-S™ cells using the Freedom ExpiCHO-S Kit. After transfection, the clonal pools were subjected to selection, limiting dilution cloning, scale-up, and initial productive screening to identify lead candidate clones (data not shown). Here we present the studies conducted to identify the top-performing clones and evaluate production stability. The lead candidate clones were tested under fed-batch conditions in an automated microbioreactor system with assessments of cell growth, titer, and specific productivity, as well as analysis of the IgG N-glycan profile of the top clone. Additionally, a clone stability study was conducted with productivity assessments over a period of 60 generations.