Immunotherapy based on bispecific T‐cell engager with hIgG 1 Fc sequence as a new therapeutic strategy in multiple myeloma

Bispecific antibodies play an important role in immunotherapy. They have received intense interest from pharmaceutical enterprises. The first antibody drug, OKT 3 (muromonab‐ CD 3), showed great performance in clinical treatment. We have successfully developed a single‐chain variable fragment (ScFv) combination of anti‐ CD 3 ScFv and anti‐ CD 138 ScFv with the hIgG 1 Fc ( hIgF c) sequence. The novel bispecific T‐cell engager (Bi TE ) with an additional hIgF c (Bi TE ‐ hIgF c, STL 001) can target T cells, natural killer cells, and multiple myeloma cells ( RPMI ‐8226 or U266). In addition, Bi TE ‐ hIgF c ( STL 001) has nanomolar‐level affinity to recombinant human CD 138 protein and shows more potent antitumor activity against RPMI ‐8226 cells than that of separate aCD 3‐ScFv‐ hIgF c and aCD 138‐ScFv‐ hIgF c, or the isotype mA b in vitro or in vivo .