Monoclonal antibodies (novel): humax-CD20, ofatumumab

Ofatumumab, the first fully human anti-CD20 monoclonal antibody, targets a novel epitope of the CD20 molecule on B-cells and releases only very slowly from the target compared with rituximab. The antibody is generated via transgenic mouse and hybridoma technology. Compared with rituximab, ofatumumab has similar ADCC, but stronger CDC, even to lymphoma cells with a low CD20 antigen density and a high number of CD55 and CD59 complement inhibitory molecules present in the cell membrane. In addition, ofatumumab kills fresh B-CLL cells resistant to rituximab. In the cynomolgus monkey model, the ofatumumab-depletion of B-cells from peripheral blood and lymph nodes lasted longer than the depletion induced by rituximab. Given the above, ofatumumab has the potential to treat B-cell malignancies with low CD20 expression, such as B-CLL and rituximab-refractory follicular lymphoma.