IgG-RFB4-SMPT-dgA Immunotoxin

**Semantic type:** Amino Acid, Peptide, or Protein|Pharmacologic Substance

**Definition:** An immunotoxin of monoclonal antibody (MoAb) RFB4 covalently linked to a single deglycosylated ricin toxin A-chain (dgA), originated from castor beans. MoAb RFB4 recognizes CD22 antigen, a B-cell adhesion protein expressed on malignant cells in about 70 percent of non-Hodgkin lymphoma and chronic lymphocytic leukemia. Ricin toxin A-chain, a potent protein synthesis inhibitor, was deglycosylated and was used in this immunoconjugate to avoid hepatic entrapment. This immunotoxin was conjugated through SMPT linker, which confers a slower breakdown of the toxin, and limits specific cytotoxicity of ricin toxin to CD22-positive malignant cells.

**Synonyms:** - IMTOX 22 - IgG-RFB4-SMPT-dgA