Used in targeted cancer therapy, particularly for multiple myeloma. Binds specifically to syndecan-1 (CD138) expressed on malignant plasma cells, enabling precise delivery of cytotoxic agents when conjugated to drugs or radionuclides. Facilitates tumor cell targeting while minimizing damage to healthy tissues. Also employed in diagnostic imaging and flow cytometry to detect and monitor CD138-positive cancers. Supports research in hematologic malignancies and development of antibody-drug conjugates.