Plamotamab (XmAb13676) is a tumor-targeted antibody that contains both a CD20 binding domain and a cytotoxic T-cell binding domain (CD3). An XmAb Bispecific Fc domain serves as the scaffold for these two antigen binding domains and confers long circulating half-life, stability and ease of manufacture on plamotamab. CD20 is highly expressed on B-cell tumor cells, including chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) cells. Engagement of CD3 by plamotamab activates T cells for highly potent and targeted killing of CD20-expressing tumor cells.
The structural stability and modularity enabled by the XmAb Bispecific Fc domain allowed the tuning of plamotamab’s potency to balance anti-tumor activity with the reduction of immune toxicity that can result from T-cell activation.