Recombinant Anti-CD7 x Anti-saporin Bispecific Antibody (Diabody) is designed to be expressed as two polypeptide chains respectively. The two chains are cross-over pairing to form a dimer. It contains a His-tag for affinity purification. This BsAb can be used in pretargeting system and deliver immunotoxin to tumor cells. It is designed for the research of Multiple myeloma (MM); Hematologic malignancies therapy.