Mark Allen Moffat

Recombinase-mediated cassette exchange (RMCE) for monoclonal antibody expression in the commercially relevant CHOK1SV cell line.

To meet product quality and cost parameters for therapeutic monoclonal antibody (mAb) production, cell lines are required to have excellent growth, stability, and productivity characteristics. In particular, cell line generation stability is critical to the success of a program, especially where high cell line generation numbers are required for large in‐market supply. However, a typical process for developing such cell lines is laborious, lengthy, and costly. In this study, we applied a FLP/FRT recombinase‐mediated cassette exchange (RMCE) system to build a site‐specific integration (SSI) system for mAb expression in the commercially relevant CHOK1SV cell line. Using a vector with a FRT‐flanked mAb expression cassette, we generated a clonal cell line with good productivity, long‐term production stability, and low mAb gene‐copy number indicating the vector was located in a ‘hot‐spot.’ A SSI host cell line was made by removing the mAb genes from the ‘hot‐spot’ by RMCE, creating a ‘landing pad’ containing two recombination cassettes that allow targeting of one or two copies of recombinant genes. Cell lines made from this host exhibited excellent growth and productivity profiles, and stability for at least 100 generations in the absence of selection agents. Importantly, while clones containing two copies had higher productivity than single copy clones, both were stable over many generations. Taken together, this study suggests the use of FLP‐based RMCE to develop SSI host cells for mAb production in CHOK1SV offers significant savings in both resources and overall cell line development time, leading to a shortened ‘time‐to‐clinic’ for therapeutic mAbs.

Human monoclonal antibodies to the insulin-like growth factor 1 receptor inhibit receptor activation and tumor growth in preclinical studies

IntroductionThe insulin-like growth factor type 1 (IGF-1) receptor contributes importantly to transformation and survival of tumor cells both in vitro and in vivo, and selective antagonists of the IGF-1 receptor (IGF-1R) activity represent an attractive experimental approach for human cancer therapy.MethodsUsing a phage display library, we identified several high-affinity fully human monoclonal antibodies with inhibitory activity against both human and rodent IGF.1Rs.ResultsThese candidate therapeutic antibodies recognized several distinct epitopes and effectively blocked ligand-mediated receptor signal transduction and cellular proliferation in vitro. They also induced IGF-1R downregulation and catabolism following antibody-mediated endocytosis. These antibodies exhibited activity against human, primate, and rodent IGF-1Rs, and dose-dependently inhibited the growth of established human tumors in nude mice.ConclusionThese fully human antibodies therefore have the potential to provide an effective anti-tumor biological therapy in the human clinical setting.