Strategy for Developing a Stable CHO Cell Line that Produces Large Titers of Trastuzumab Antibody.

Abstract

Trastuzumab (Herceptin®) is currently the main treatment option for breast cancer patients that overexpress the human epidermal growth factor receptor 2 (HER2). This antibody binds specifically to HER2, blocks cancer cell growth, and promotes effective cell death. In the present study, we sought to develop a robust and efficient process for the development of a stable Chinese hamster ovary (CHO) cell line with high trastuzumab expression and production. We adapted a process that combines transposon system-based vector construction, suspension cell culture, and a high selection process. The latter, involved enhanced green fluorescent protein (eGFP) expression, fluorescence-activated cell sorting (FACS), and semi-solid methylcellulose media. The construction of trastuzumab as a humanized monoclonal antibody was achieved by subcloning the synthesized light and heavy chain sequences into a suitable piggyBac expression vector. The optimized piggyBac vector used for the expression of trastuzumab in CHO cells resulted in the production of trastuzumab and reached 4.24 g/L in the T1A7 clone after a 7-day batch culture. The T1A7 clone was selected after screening over 1500 clones. The current simple workflow ensures strict monoclonality and relatively high production of trastuzumab. This workflow could potentially be implemented in Research and Development (R&D) laboratories, including in developing countries for the production of recombinant monoclonal antibodies in a cost-effective manner.