Development of a Humanized Antibody 5D3Hu against the PRAME Tumor Antigen

The PRAME antigen, which is a significant target for monoclonal antibodies, is a tumor-specific marker that is active at all stages of tumor cell differentiation; it induces a spontaneous T-cell response. In this work, a humanized 5D3Hu antibody was constructed on the basis of the mouse monoclonal antibody 5D3 to the PRAME protein and produced in CHO (Chinese hamster ovary tumor) cells. The 5D3Hu antibody demonstrated high affinity for the antigen (1.4 nM), binding to both recombinant and native PRAME protein; it also had an inhibitory effect on the proliferation of PRAME-positive cell lines. These results allow considering the humanized 5D3Hu antibody as a promising therapeutic agent for the treatment of oncological diseases in which overexpression of the PRAME protein is observed.