Disclosed is a method and composition for treating a disease associated with target cells expressing CD138 in a multiple dose regimen. An immunoconjugate comprising an engineered targeting antibody targeting CD138 expressing cells and an effector molecule is administered in a multiple dose regimen. The multiple dose regimen comprises at least two doses and the aggregate dose administered within an active treatment cycle is an aggregate maximum tolerable dose (AMTD) or a fraction of the AMTD. The AMTD and/or said fraction exceeds the dose resulting in dose limiting toxicity (DLT) and/or exceeds the maximum tolerable dose (MTD) when the immunoconjugate is administered as a single dose, including as part of a multiple single dose regimen within said active treatment cycle.
