A bispecific T-cell engager (TCE) and bispecific antibody directed against both the tumor-associated antigen (TAA) mesothelin (MSLN) and the T-cell surface antigen CD3, with potential immunostimulating and antineoplastic activities. Upon administration, anti-mesothelin T-cell engaging bispecific antibody JNJ-79032421 targets and binds to MSLN expressed on tumor cells and to CD3 expressed on cytotoxic T-lymphocytes (CTLs). This activates and redirects CTLs to MSLN-expressing tumor cells, which results in the CTL-mediated death of MSLN-expressing tumor cells. MSLN, a cell surface glycoprotein involved in cell adhesion, is overexpressed in a variety of cancer cell types.