The present invention provides to a bispecific single chain antibody construct binding to a target cell surface antigen via a first binding domain and to the T cell surface antigen CD3 via a second binding domain, wherein serum albumin is fused to the C-terminus of the antibody construct. Moreover, the invention provides a polynucleotide encoding the antibody construct, a vector comprising said polynucleotide and a host cell transformed or transfected with said vector. Furthermore, the invention provides a process for the production of the antibody construct of the invention, a medical use of said antibody construct and a kit comprising said antibody construct.本發明提供一種經由第一結合域結合至靶細胞表面抗原及經由第二結合域結合至T細胞表面抗原CD3之雙特異性單鏈抗體構築體，其中血清白蛋白係融合至該抗體構築體之C端。此外，本發明提供編碼該抗體構築體之聚核苷酸、包括該聚核苷酸之載體及經該載體轉形或轉染之宿主細胞。此外，本發明提供一種用於製造本發明之抗體構築體之方法；該抗體構築體之醫學應用及包括該抗體構築體之套組。
