Plamotamab is a tumor-targeted antibody that contains both a CD20 binding domain and a cytotoxic T-cell binding domain (CD3). Xencor’s 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 non-Hodgkin lymphoma (NHL) cells. Engagement of CD3 by plamotamab activates T cells for highly potent and targeted killing of CD20-expressing tumor cells.
Xencor has entered into a global collaboration and license agreement with Janssen Biotech, Inc., to develop multiple highly active, chemotherapy-free regimens to treat patients with B-cell cancers. Janssen received worldwide exclusive development and commercial rights to plamotamab, and Xencor will collaborate with Janssen on further clinical development of plamotamab. Under the collaboration, Xencor and Janssen will develop B-cell targeted CD28 bispecific antibodies to selectively enhance T-cell cytotoxic activity in combination with plamotamab.
Safety and anti-tumor activity from the Phase 1 intravenous dose-escalation study in patients with relapsed or refractory NHL indicated that plamotamab was generally well tolerated and demonstrated encouraging clinical activity as a monotherapy.
Xencor is conducting a Phase 1 monotherapy study of plamotamab with subcutaneous dose escalations in patients with relapsed or refractory non-Hodgkin lymphoma.