Bi-specific diabodies comprise two or more polypeptide chains and possess at least one Epitope-Binding Site that is immunospecific for an epitope of PD-1 and at least one Epitope-Binding Site that is immunospecific for an epitope of LAG-3 (i.e., a “PD-1 x LAG-3 bi-specific diabody”). More preferably, bi-specific diabodies comprise four polypeptide chains and possess two Epitope-Binding Sites that are immunospecific for one (or two) epitope(s) of PD-1 and two Epitope-Binding Site that are immunospecific for one (or two) epitope(s) of LAG-3 (i.e.,“PD-1 x LAG-3 bi-specific, tetra-valent diabody”). The diabodies that additionally comprise an immunoglobulin Fc Domain (“bispecific Fc diabodies and bi-specific, tetra-valent, Fc diabodies”). The diabodies are capable of simultaneously binding to PD-1 and to LAG-3, particularly as such molecules are arrayed on the surfaces of human cells. Pharmaceutical compositions that contain such diabodies, and methods involving the use of such diabodies in the treatment of cancer and other diseases and conditions are provided.一種雙特異性雙抗體，其包括兩條或更多條多肽鏈，並且其具有對PD-1的表位為免疫特異性的至少一個表位結合位點和對LAG-3的表位為免疫特異性的至少一個表位結合位點(即，“PD-1 x LAG-3雙特異性雙抗體”)。更優選地，一種雙特異性雙抗體，其包括四條多肽鏈，並且其具有對PD-1的一個(或兩個)表位為免疫特異性的兩個表位結合位點和對LAG-3的一個(或兩個)表位為免疫特異性的兩個表位結合位點(即，“PD-1 x LAG-3雙特異性、四價雙抗體”)。再者，一種雙抗體，其另外包括免疫球蛋白Fc結構域 (即，“雙特異性Fc雙抗體和雙特異性、四價Fc雙抗體”)。於此，雙抗體能夠同時結合PD-1和LAG-3，尤其是當這樣的分子排列在人細胞的表面上時。並且涉及包含這樣的雙抗體的藥學組合物，並且涉及使用這樣的雙抗體治療癌症和其他疾病和病況的方法。
