Study of the Antiproliferative Activity of a Humanized Antibody to the Cancer-Testis Antigen PRAME

Objective: The PRAME antigen (Preferentially Expressed Antigen in Melanoma), a cancer-testis antigen expressed in various tumor types, represents an attractive target for targeted cancer therapy. Methods: A humanized antibody (6H8Hu) was developed based on the monoclonal antibody 6H8 specific to the PRAME protein. The antibody was produced in CHO cells. Results and Discussion: The humanized antibody retains the high affinity of the parental mAb to the antigen (1.2 nM), binds to both recombinant and native PRAME protein, inhibits the proliferation of the PRAME-positive human melanoma cell line Mel Ibr, and suppresses tumor nodule growth in vivo to a degree comparable to that of the murine antibody 6H8 and the cytostatic agent melphalan. Conclusions: The humanized antibody 6H8Hu is a promising candidate for targeted therapy against PRAME-positive melanoma, showing potential comparable to murine antibodies and conventional cytotoxic treatments.