An antibody molecule that binds to programmed death-ligand 1 (PD-L1) and CD137, comprising: (a) a complementarity determining region -based antigen-binding site for PD-L1; and (b) a CD137 antigen-binding site located in a CH3 domain of the antibody molecule, wherein the CD137 antigen-binding site comprises a first sequence and a second sequence located in the AB and EF structural loops of the CH3 domain, respectively, wherein the first sequence is located between positions 14 and 17 of the CH3 domain and the second sequence is located between positions 91 and 99 of the CH3 domain, wherein the amino acid residue numbering is according to the IMGT numbering scheme, and wherein the antibody molecule comprises the VH domain, VL domain, first sequence and second sequence set forth in: (i) SEQ ID NOs 12, 14, 113 and 114, respectively [FS22-172-003-AA/E12v2]; (ii) SEQ ID NOs 23, 25, 113 and 114, respectively [FS22-172-003-AA/E05v2]; (iii) SEQ ID NOs 23, 30, 113 and 114, respectively [FS22-172-003-AA/G12v2]; (iv) SEQ ID NOs 12, 14, 79 and 80, respectively [FS22-053-008-AA/E12v2]; (v) SEQ ID NOs 23, 25, 79 and 80, respectively [FS22-053-008-AA/E05v2]; (vi) SEQ ID NOs 12, 14, 79 and 89, respectively [FS22-053-017-AA/E12v2]; (vii) SEQ ID NOs 23, 25, 79 and 89, respectively [FS22-053-017-AA/E05v2]; or (viii) SEQ ID NOs 23, 30, 79 and 89, respectively [FS22-053-017-AA/G12v2]. (a) a complementarity determining region -based antigen-binding site for PD-L1; and (b) a CD137 antigen-binding site located in a CH3 domain of the antibody molecule, wherein the CD137 antigen-binding site comprises a first sequence and a second sequence located in the AB and EF structural loops of the CH3 domain, respectively, wherein the first sequence is located between positions 14 and 17 of the CH3 domain and the second sequence is located between positions 91 and 99 of the CH3 domain, wherein the amino acid residue numbering is according to the IMGT numbering scheme, and wherein the antibody molecule comprises the VH domain, VL domain, first sequence and second sequence set forth in: (i) SEQ ID NOs 12, 14, 113 and 114, respectively [FS22-172-003-AA/E12v2]; (ii) SEQ ID NOs 23, 25, 113 and 114, respectively [FS22-172-003-AA/E05v2]; (iii) SEQ ID NOs 23, 30, 113 and 114, respectively [FS22-172-003-AA/G12v2]; (iv) SEQ ID NOs 12, 14, 79 and 80, respectively [FS22-053-008-AA/E12v2]; (v) SEQ ID NOs 23, 25, 79 and 80, respectively [FS22-053-008-AA/E05v2]; (vi) SEQ ID NOs 12, 14, 79 and 89, respectively [FS22-053-017-AA/E12v2]; (vii) SEQ ID NOs 23, 25, 79 and 89, respectively [FS22-053-017-AA/E05v2]; or (viii) SEQ ID NOs 23, 30, 79 and 89, respectively [FS22-053-017-AA/G12v2]. (i) SEQ ID NOs 12, 14, 113 and 114, respectively [FS22-172-003-AA/E12v2]; (ii) SEQ ID NOs 23, 25, 113 and 114, respectively [FS22-172-003-AA/E05v2]; (iii) SEQ ID NOs 23, 30, 113 and 114, respectively [FS22-172-003-AA/G12v2]; (iv) SEQ ID NOs 12, 14, 79 and 80, respectively [FS22-053-008-AA/E12v2]; (v) SEQ ID NOs 23, 25, 79 and 80, respectively [FS22-053-008-AA/E05v2]; (vi) SEQ ID NOs 12, 14, 79 and 89, respectively [FS22-053-017-AA/E12v2]; (vii) SEQ ID NOs 23, 25, 79 and 89, respectively [FS22-053-017-AA/E05v2]; or (viii) SEQ ID NOs 23, 30, 79 and 89, respectively [FS22-053-017-AA/G12v2].