Recombinant Anti-CD38 x Anti-saporin Bispecific Antibody (scFv-CH3) contains two chains. The anti-CD38 scFv is fused to the Knob-CH3 domain via a hinge region and the same as the anti-saporin scFv to the Hole-CH3 domain, or vice versa. The KIH CH3 domains can facilitate to form a heterodimer and this bivalent binding leads to improvement in avidity. 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.