Background/Objectives: Immune checkpoint blockade, particularly targeting the programmed
cell death 1 (PD-1) receptor, is a promising strategy in cancer immunotherapy. The
interaction between PD-1 and its ligands, PD-L1 and PD-L2, is crucial in immune evasion
by tumors. Blocking this interaction with monoclonal antibodies like Nivolumab can
restore anti-tumor immunity. This study aims to develop a stable expression system
for Nivolumab-based anti-PD-1 in the Chinese Hamster Ovary (CHO) DG44 cell line using
two different expression vector systems with various signal sequences. Methods: The
heavy chain (HC) and light chain (LC) of Nivolumab were cloned into two expression
vectors, pOptiVEC and pcDNA3.3. Each vector was engineered with two distinct signal
sequences, resulting in the creation of eight recombinant plasmids. These plasmids
were co-transfected into CHO DG44 cells in different combinations, allowing for the
assessment of stable antibody production. Results: Both pOptiVEC and pcDNA3.3 vectors
were successful in stably integrating and expressing the Nivolumab-based anti-PD-1
antibody in CHO DG44 cells. This study found that the choice of signal sequence significantly
influenced the quantity of antibodies produced. The optimization of production conditions
further enhanced antibody yield, indicating the potential for large-scale production.
Conclusions: This study demonstrates that both pOptiVEC and pcDNA3.3 expression systems
are effective for the stable production of Nivolumab-based anti-PD-1 in CHO DG44 cells.
Signal sequences play a critical role in determining the expression levels, and optimizing
production conditions can further increase antibody yield, supporting future applications
in cancer immunotherapy.