A T-cell engaging bispecific antibody directed against both the tumor-associated antigen (TAA) G-protein coupled receptor family C group 5 member D (GPRC5D) and the T-cell surface antigen CD3, with potential antineoplastic activity. Upon administration, forimtamig binds to both GPRC5D expressed on tumor cells and CD3 on T-cells. This results in the cross-linking of T-cells and tumor cells and induces a potent cytotoxic T-lymphocyte (CTL) response against GPRC5D-expressing tumor cells. GPRC5D is overexpressed on certain tumors, such as multiple myeloma, while minimally expressed on normal, healthy cells, and plays a key role in tumor cell proliferation.