A bispecific antibody targeting both the tumor-associated antigen (TAA) carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5; CEA) and the costimulatory receptor 4-1BB (CD137; tumor necrosis factor receptor superfamily member 9; TNFRSF9), with potential immunostimulating and antineoplastic activities. Upon administration, anti-CEA/anti-4-1BB bispecific antibody BGB-B167 simultaneously targets and binds to CEA expressed on tumor cells and 4-1BB expressed on activated T-lymphocytes and natural killer (NK) cells. This crosslinks CEA-expressing tumor cells and 4-1BB-expressing T-cells and NK cells, and activates 4-1BB signaling locally in the tumor microenvironment (TME). This results in cytotoxic T-cell co-stimulation, enhances T-lymphocyte-mediated anti-tumor activity and leads to cytotoxic T-cell-mediated lysis of CEA-expressing tumor cells. The binding of BGB-B167 to CEA may also prevent CEA-mediated signaling. CEA is overexpressed by a variety of cancer cell types and plays a key role in cell migration, cell invasion, and cell adhesion. 4-1BB, a surface glycoprotein of the tumor necrosis factor receptor superfamily, is an inducible costimulatory receptor that plays a key role in T-cell proliferation, survival and cytolytic activity.