Using a Dihydrofolate Reductase-Based Strategy for Producing the Biosimilar Version of Pertuzumab in CHO-S Cells

Targeted therapy using monoclonal antibodies (mAbs) against epidermal growth factor receptor-2 (ErbB2) has been utilized for the treatment of breast cancer, recently. Pertuzumab, one of the anti-ErbB2 mAbs, was approved by FDA in 2012 for the treatment of metastatic breast cancer. The aim of this study was to produce biosimilar version of pertuzumab in Chinese hamster ovary (CHO)-S cell line, and compare its ErbB2-binding and biological activities, with commercial drug, Perjeta. To this end, a dihydrofolate reductase (DHFR)-based strategy was used to produce a CHO-S stable cell pool capable of producing high levels of pertuzumab. A two-phase selection strategy based on increasing concentrations of puromycin and MTX was used for selection of stably transfected cell pools. Finally, three stable CHO-S cell pools were achieved and analyzed for productivity in a simple fed-batch culture system. Results showed that, the pool with Puromycin to the final concentration of 50 μg/mL and MTX to 1000 nM in the selection phase 2 produced and secreted the highest amount of mAb (442.578 mg/L at 8 days) to the culture medium. Assessment of in vitro ErbB2-binding and biological activities of produced pertuzumab revealed its high similarity with Perjeta.