Abstract 2658: GPEx® system to increase production of pritumumab in a CHO cell line

Abstract

Abstract Pritumumab, a natural human IgG1 kappa antibody isolated from a lymph node of a patient with cervical carcinoma, has been used in a Phase II setting with brain cancer patients. The original human-human hybridoma secreted approximately 1 picogram of antibody per cell per day. This level of the antibody production posed cost constrains for late stage therapeutic clinical trials. To generate a more commercially viable antibody, a pritumumab-secreting Chinese hamster ovary (CHO) cell line was created using the GPEx® technology. This technology involved construction and cloning of heavy and light chain DNA. Both DNA sequences were cloned into the expression vector and transduced into HEK 293 cells that constitutively produces the MLV gag, pro, and pol. The pritumumab cell line was made by performing multiple rounds of transduction (multiplicity of > 1000 retrovector particles/cell) of the GPEx® Chinese Hamster Ovary (GCHO) parental cell line with retrovector made from the gene construct developed to express the pritumumab antibody light chain (LC) and the pritumumab antibody heavy chain (HC). Five independent transductions were performed: two LC and three HC. Limiting dilution method was used to establish clonal cell lines. Top clones were selected based on pritumumab antibody titer. Pritumumab expression was determined by Protein A HPLC using a generic IgG standard. Clearly, single copies of genes were inserted efficiently in unique locations throughout the genome of the CHO cells to obtain genetically stable cell line that expressed high levels of the antibody, and represented more than a 40-fold increase in production of the antibody over the original hybridoma. Flow cytometry binding and immunohistological analyses demonstrated comparability between the recombinant form of pritumumab and the hybridoma form of the protein. Thus, high level of specific productivities and titers of the CHO clones developed through the GPEx® system will allow the therapeutic antibody program to move forward into large and extended clinical trials. Citation Format: Gregory T. Bleck, Rishab K. Gupta, Beatrix Kotlan, Dona York, Mark C. Glassy. GPEx® system to increase production of pritumumab in a CHO cell line. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2658. doi:10.1158/1538-7445.AM2014-2658